From eacc092f87bd3ffefeb16de7e952aa94d18ed436 Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Fri, 19 Feb 2016 11:33:32 -0800
Subject: [PATCH 1/5] Add cases and baselines from #6211 and #6210

---
 .../nonIdenticalTypeConstraints.errors.txt    | 50 +++++++++++++
 .../reference/nonIdenticalTypeConstraints.js  | 71 +++++++++++++++++++
 .../compiler/nonIdenticalTypeConstraints.ts   | 38 ++++++++++
 3 files changed, 159 insertions(+)
 create mode 100644 tests/baselines/reference/nonIdenticalTypeConstraints.errors.txt
 create mode 100644 tests/baselines/reference/nonIdenticalTypeConstraints.js
 create mode 100644 tests/cases/compiler/nonIdenticalTypeConstraints.ts

diff --git a/tests/baselines/reference/nonIdenticalTypeConstraints.errors.txt b/tests/baselines/reference/nonIdenticalTypeConstraints.errors.txt
new file mode 100644
index 00000000000..a8b54bf44dd
--- /dev/null
+++ b/tests/baselines/reference/nonIdenticalTypeConstraints.errors.txt
@@ -0,0 +1,50 @@
+tests/cases/compiler/nonIdenticalTypeConstraints.ts(10,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/compiler/nonIdenticalTypeConstraints.ts(16,7): error TS2428: All declarations must have identical type parameters.
+tests/cases/compiler/nonIdenticalTypeConstraints.ts(36,11): error TS2428: All declarations must have identical type parameters.
+
+
+==== tests/cases/compiler/nonIdenticalTypeConstraints.ts (3 errors) ====
+    class Different {
+        a: number;
+        b: string;
+        c: boolean;
+    }
+    
+    class Foo<T extends Function> {
+        n: T;
+    }
+    interface Foo<T extends Different> {
+              ~~~
+!!! error TS2428: All declarations must have identical type parameters.
+        y: T;
+    }
+    interface Qux<T extends Different> {
+        y: T;
+    }
+    class Qux<T extends Function> {
+          ~~~
+!!! error TS2428: All declarations must have identical type parameters.
+        n: T;
+    }
+    
+    class Bar<T extends Function> {
+        n: T;
+    }
+    interface Bar<T extends Function> {
+        y: T;
+    }
+    interface Baz<T extends Function> {
+        y: T;
+    }
+    class Baz<T extends Function> {
+        n: T;
+    }
+    
+    class Quux<T> {
+        n: T;
+    }
+    interface Quux<U> {
+              ~~~~
+!!! error TS2428: All declarations must have identical type parameters.
+        m: U;
+    }
\ No newline at end of file
diff --git a/tests/baselines/reference/nonIdenticalTypeConstraints.js b/tests/baselines/reference/nonIdenticalTypeConstraints.js
new file mode 100644
index 00000000000..73748f63885
--- /dev/null
+++ b/tests/baselines/reference/nonIdenticalTypeConstraints.js
@@ -0,0 +1,71 @@
+//// [nonIdenticalTypeConstraints.ts]
+class Different {
+    a: number;
+    b: string;
+    c: boolean;
+}
+
+class Foo<T extends Function> {
+    n: T;
+}
+interface Foo<T extends Different> {
+    y: T;
+}
+interface Qux<T extends Different> {
+    y: T;
+}
+class Qux<T extends Function> {
+    n: T;
+}
+
+class Bar<T extends Function> {
+    n: T;
+}
+interface Bar<T extends Function> {
+    y: T;
+}
+interface Baz<T extends Function> {
+    y: T;
+}
+class Baz<T extends Function> {
+    n: T;
+}
+
+class Quux<T> {
+    n: T;
+}
+interface Quux<U> {
+    m: U;
+}
+
+//// [nonIdenticalTypeConstraints.js]
+var Different = (function () {
+    function Different() {
+    }
+    return Different;
+}());
+var Foo = (function () {
+    function Foo() {
+    }
+    return Foo;
+}());
+var Qux = (function () {
+    function Qux() {
+    }
+    return Qux;
+}());
+var Bar = (function () {
+    function Bar() {
+    }
+    return Bar;
+}());
+var Baz = (function () {
+    function Baz() {
+    }
+    return Baz;
+}());
+var Quux = (function () {
+    function Quux() {
+    }
+    return Quux;
+}());
diff --git a/tests/cases/compiler/nonIdenticalTypeConstraints.ts b/tests/cases/compiler/nonIdenticalTypeConstraints.ts
new file mode 100644
index 00000000000..c0271edc91a
--- /dev/null
+++ b/tests/cases/compiler/nonIdenticalTypeConstraints.ts
@@ -0,0 +1,38 @@
+class Different {
+    a: number;
+    b: string;
+    c: boolean;
+}
+
+class Foo<T extends Function> {
+    n: T;
+}
+interface Foo<T extends Different> {
+    y: T;
+}
+interface Qux<T extends Different> {
+    y: T;
+}
+class Qux<T extends Function> {
+    n: T;
+}
+
+class Bar<T extends Function> {
+    n: T;
+}
+interface Bar<T extends Function> {
+    y: T;
+}
+interface Baz<T extends Function> {
+    y: T;
+}
+class Baz<T extends Function> {
+    n: T;
+}
+
+class Quux<T> {
+    n: T;
+}
+interface Quux<U> {
+    m: U;
+}
\ No newline at end of file

From bb2eb635d60c7b63da580e130beacea386b28507 Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Fri, 19 Feb 2016 11:36:35 -0800
Subject: [PATCH 2/5] Merged classes and interfaces must have identical type
 constraints

Previously, only interfaces needed to check this, but now that classes and
interfaces can merge, the check needs to happen in more places.
---
 src/compiler/checker.ts              | 28 +++++++++++++++++++++-------
 src/compiler/diagnosticMessages.json |  4 ++--
 2 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index eddddb5cb2b..b9a8ab6cd2c 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -14013,7 +14013,7 @@ namespace ts {
             }
         }
 
-        // Check each type parameter and check that list has no duplicate type parameter declarations
+        /** Check each type parameter and check that type parameters have no duplicate type parameter declarations */
         function checkTypeParameters(typeParameterDeclarations: TypeParameterDeclaration[]) {
             if (typeParameterDeclarations) {
                 for (let i = 0, n = typeParameterDeclarations.length; i < n; i++) {
@@ -14031,6 +14031,23 @@ namespace ts {
             }
         }
 
+        /** Check that type parameter lists are identical across multiple declarations */
+        function checkTypeParameterListsIdentical(node: ClassLikeDeclaration | InterfaceDeclaration, symbol: Symbol) {
+            let firstDecl: ClassLikeDeclaration | InterfaceDeclaration;
+            if (symbol.declarations.length > 1) {
+                for (const declaration of symbol.declarations) {
+                    if (declaration.kind === SyntaxKind.ClassDeclaration || declaration.kind === SyntaxKind.InterfaceDeclaration) {
+                        if (!firstDecl) {
+                            firstDecl = <ClassLikeDeclaration | InterfaceDeclaration>declaration;
+                        }
+                        else if (!areTypeParametersIdentical(firstDecl.typeParameters, node.typeParameters)) {
+                            error(node.name, Diagnostics.All_declarations_must_have_identical_type_parameters);
+                        }
+                    }
+                }
+            }
+        }
+
         function checkClassExpression(node: ClassExpression): Type {
             checkClassLikeDeclaration(node);
             checkNodeDeferred(node);
@@ -14064,6 +14081,7 @@ namespace ts {
             const type = <InterfaceType>getDeclaredTypeOfSymbol(symbol);
             const typeWithThis = getTypeWithThisArgument(type);
             const staticType = <ObjectType>getTypeOfSymbol(symbol);
+            checkTypeParameterListsIdentical(node, symbol);
 
             const baseTypeNode = getClassExtendsHeritageClauseElement(node);
             if (baseTypeNode) {
@@ -14326,14 +14344,10 @@ namespace ts {
 
                 checkExportsOnMergedDeclarations(node);
                 const symbol = getSymbolOfNode(node);
-                const firstInterfaceDecl = <InterfaceDeclaration>getDeclarationOfKind(symbol, SyntaxKind.InterfaceDeclaration);
-                if (symbol.declarations.length > 1) {
-                    if (node !== firstInterfaceDecl && !areTypeParametersIdentical(firstInterfaceDecl.typeParameters, node.typeParameters)) {
-                        error(node.name, Diagnostics.All_declarations_of_an_interface_must_have_identical_type_parameters);
-                    }
-                }
+                checkTypeParameterListsIdentical(node, symbol);
 
                 // Only check this symbol once
+                const firstInterfaceDecl = <InterfaceDeclaration>getDeclarationOfKind(symbol, SyntaxKind.InterfaceDeclaration);
                 if (node === firstInterfaceDecl) {
                     const type = <InterfaceType>getDeclaredTypeOfSymbol(symbol);
                     const typeWithThis = getTypeWithThisArgument(type);
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 16cf1911642..92396d005b7 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1311,7 +1311,7 @@
         "category": "Error",
         "code": 2427
     },
-    "All declarations of an interface must have identical type parameters.": {
+    "All declarations must have identical type parameters.": {
         "category": "Error",
         "code": 2428
     },
@@ -2801,4 +2801,4 @@
         "category": "Error",
         "code": 17009
     }
-}
+}

From 0d3f6473cf36127777aeb75bd3676ca5fb14ad96 Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Fri, 19 Feb 2016 11:46:47 -0800
Subject: [PATCH 3/5] Rebaseline messages in existing tests

---
 ...nstructSignaturesWithOverloads2.errors.txt |  4 +-
 ...acesWithDuplicateTypeParameters.errors.txt |  4 +-
 ...GenericInterfaceWithTheSameName.errors.txt | 12 ++---
 ...terfaceWithMultipleDeclarations.errors.txt | 44 +++++++++----------
 .../multipleNumericIndexers.errors.txt        |  4 +-
 ...cesDifferingByTypeParameterName.errors.txt | 20 ++++-----
 ...esDifferingByTypeParameterName2.errors.txt | 12 ++---
 ...erfacesWithDifferentConstraints.errors.txt | 12 ++---
 ...ithTheSameNameButDifferentArity.errors.txt | 12 ++---
 9 files changed, 62 insertions(+), 62 deletions(-)

diff --git a/tests/baselines/reference/constructSignaturesWithOverloads2.errors.txt b/tests/baselines/reference/constructSignaturesWithOverloads2.errors.txt
index ceb828dd061..4f0a5944659 100644
--- a/tests/baselines/reference/constructSignaturesWithOverloads2.errors.txt
+++ b/tests/baselines/reference/constructSignaturesWithOverloads2.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/conformance/types/objectTypeLiteral/constructSignatures/constructSignaturesWithOverloads2.ts(32,11): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/types/objectTypeLiteral/constructSignatures/constructSignaturesWithOverloads2.ts(32,11): error TS2428: All declarations must have identical type parameters.
 
 
 ==== tests/cases/conformance/types/objectTypeLiteral/constructSignatures/constructSignaturesWithOverloads2.ts (1 errors) ====
@@ -35,7 +35,7 @@ tests/cases/conformance/types/objectTypeLiteral/constructSignatures/constructSig
     
     interface I<T> {
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
         new (x: T, y?: number): C2<T>;
         new (x: T, y: number): C2<T>;
     }
diff --git a/tests/baselines/reference/extendedInterfacesWithDuplicateTypeParameters.errors.txt b/tests/baselines/reference/extendedInterfacesWithDuplicateTypeParameters.errors.txt
index 7d7fea1b2c6..ebe2cd05aec 100644
--- a/tests/baselines/reference/extendedInterfacesWithDuplicateTypeParameters.errors.txt
+++ b/tests/baselines/reference/extendedInterfacesWithDuplicateTypeParameters.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts(1,42): error TS2300: Duplicate identifier 'A'.
-tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts(9,11): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts(9,11): error TS2428: All declarations must have identical type parameters.
 tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts(9,38): error TS2300: Duplicate identifier 'C'.
 
 
@@ -16,7 +16,7 @@ tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts(9,38): err
     
     interface InterfaceWithSomeTypars<C, C> { // should error
               ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
                                          ~
 !!! error TS2300: Duplicate identifier 'C'.
     	bar2(): void;
diff --git a/tests/baselines/reference/genericAndNonGenericInterfaceWithTheSameName.errors.txt b/tests/baselines/reference/genericAndNonGenericInterfaceWithTheSameName.errors.txt
index 4c3245b11f7..ae02c434d25 100644
--- a/tests/baselines/reference/genericAndNonGenericInterfaceWithTheSameName.errors.txt
+++ b/tests/baselines/reference/genericAndNonGenericInterfaceWithTheSameName.errors.txt
@@ -1,6 +1,6 @@
-tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(7,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(16,15): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(40,22): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(7,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(16,15): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(40,22): error TS2428: All declarations must have identical type parameters.
 
 
 ==== tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts (3 errors) ====
@@ -12,7 +12,7 @@ tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterf
     
     interface A<T> { // error
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
         bar: T;
     }
     
@@ -23,7 +23,7 @@ tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterf
     
         interface A { // error
                   ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
             foo: string;
         }
     }
@@ -49,7 +49,7 @@ tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterf
     module M3 {
         export interface A<T> { // error
                          ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
             bar: T;
         }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/interfaceWithMultipleDeclarations.errors.txt b/tests/baselines/reference/interfaceWithMultipleDeclarations.errors.txt
index e4b37db8a7a..5cd4f2f7d96 100644
--- a/tests/baselines/reference/interfaceWithMultipleDeclarations.errors.txt
+++ b/tests/baselines/reference/interfaceWithMultipleDeclarations.errors.txt
@@ -1,14 +1,14 @@
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(3,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(5,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(7,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(9,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(11,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(16,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(18,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(20,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(22,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(24,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(29,11): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(3,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(5,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(7,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(9,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(11,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(16,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(18,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(20,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(22,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(24,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(29,11): error TS2428: All declarations must have identical type parameters.
 
 
 ==== tests/cases/compiler/interfaceWithMultipleDeclarations.ts (11 errors) ====
@@ -16,53 +16,53 @@ tests/cases/compiler/interfaceWithMultipleDeclarations.ts(29,11): error TS2428:
     }
     interface I1<S> { // Name mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
     }
     interface I1<T, U extends T> { // Length mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
     }
     interface I1<V extends string> { // constraint present
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
     }
     interface I1<V, X extends V> { // Length mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
     }
     interface I1 { // Length mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
     }
     
     interface I2<T extends string> {
     }
     interface I2<T extends () => string> { // constraint mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
     }
     interface I2<T> { // constraint absent
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
     }
     interface I2<U> { // name mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
     }
     interface I2<X, Y> { // length mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
     }
     interface I2 { // length mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
     }
     
     interface I3 {
     }
     interface I3<T> { // length mismatch
               ~~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
     }
     
     class Foo<T> {
diff --git a/tests/baselines/reference/multipleNumericIndexers.errors.txt b/tests/baselines/reference/multipleNumericIndexers.errors.txt
index 856fdbe47ff..11fb81ba5b3 100644
--- a/tests/baselines/reference/multipleNumericIndexers.errors.txt
+++ b/tests/baselines/reference/multipleNumericIndexers.errors.txt
@@ -3,7 +3,7 @@ tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericI
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(15,5): error TS2375: Duplicate number index signature.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(20,5): error TS2375: Duplicate number index signature.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(25,5): error TS2375: Duplicate number index signature.
-tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(28,11): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(28,11): error TS2428: All declarations must have identical type parameters.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(29,5): error TS2375: Duplicate number index signature.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(30,5): error TS2375: Duplicate number index signature.
 
@@ -48,7 +48,7 @@ tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericI
     
     interface I<T> {
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
         [x: number]: string;
         ~~~~~~~~~~~~~~~~~~~~
 !!! error TS2375: Duplicate number index signature.
diff --git a/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName.errors.txt b/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName.errors.txt
index adf9583095d..6b56f5dfef6 100644
--- a/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName.errors.txt
+++ b/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName.errors.txt
@@ -1,8 +1,8 @@
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(7,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(15,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(24,15): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(32,15): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(56,22): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(7,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(15,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(24,15): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(32,15): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(56,22): error TS2428: All declarations must have identical type parameters.
 
 
 ==== tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts (5 errors) ====
@@ -14,7 +14,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
     interface A<U> { // error
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
         y: U;
     }
     
@@ -24,7 +24,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
     interface B<T,V> { // error
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
         y: V;
     }
     
@@ -35,7 +35,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
         interface A<U> { // error
                   ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
             y: U;
         }
     
@@ -45,7 +45,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
         interface B<T, V> { // error
                   ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
             y: V;
         }
     }
@@ -71,7 +71,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     module M3 {
         export interface B<T, V> { // error
                          ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
             y: V;
         }
     }
diff --git a/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName2.errors.txt b/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName2.errors.txt
index dd1483b9e1d..7caec272386 100644
--- a/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName2.errors.txt
+++ b/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName2.errors.txt
@@ -1,7 +1,7 @@
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(7,11): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(7,11): error TS2428: All declarations must have identical type parameters.
 tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(8,8): error TS2304: Cannot find name 'V'.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(16,15): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(40,22): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(16,15): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(40,22): error TS2428: All declarations must have identical type parameters.
 
 
 ==== tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts (4 errors) ====
@@ -13,7 +13,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
     interface B<U, T> { // error
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
         y: V;
            ~
 !!! error TS2304: Cannot find name 'V'.
@@ -26,7 +26,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
         interface B<U, T> { // error
                   ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
             y: T;
         }
     }
@@ -52,7 +52,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     module M3 {
         export interface B<U, T> { // error
                          ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
             y: T;
         }
     }
diff --git a/tests/baselines/reference/twoGenericInterfacesWithDifferentConstraints.errors.txt b/tests/baselines/reference/twoGenericInterfacesWithDifferentConstraints.errors.txt
index 665a26f47f4..39e684ec3dd 100644
--- a/tests/baselines/reference/twoGenericInterfacesWithDifferentConstraints.errors.txt
+++ b/tests/baselines/reference/twoGenericInterfacesWithDifferentConstraints.errors.txt
@@ -1,6 +1,6 @@
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(5,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(14,15): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(38,22): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(5,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(14,15): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(38,22): error TS2428: All declarations must have identical type parameters.
 
 
 ==== tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts (3 errors) ====
@@ -10,7 +10,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDi
     
     interface A<T extends Number> { // error
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
         y: T;
     }
     
@@ -21,7 +21,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDi
     
         interface B<T extends A<any>> { // error
                   ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
             y: T;
         }
     }
@@ -47,7 +47,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDi
     module M3 {
         export interface A<T extends Number> { // error
                          ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
             y: T;
         }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/twoGenericInterfacesWithTheSameNameButDifferentArity.errors.txt b/tests/baselines/reference/twoGenericInterfacesWithTheSameNameButDifferentArity.errors.txt
index be0608c0cd6..e31a8d5c433 100644
--- a/tests/baselines/reference/twoGenericInterfacesWithTheSameNameButDifferentArity.errors.txt
+++ b/tests/baselines/reference/twoGenericInterfacesWithTheSameNameButDifferentArity.errors.txt
@@ -1,6 +1,6 @@
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(5,11): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(14,15): error TS2428: All declarations of an interface must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(38,22): error TS2428: All declarations of an interface must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(5,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(14,15): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(38,22): error TS2428: All declarations must have identical type parameters.
 
 
 ==== tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts (3 errors) ====
@@ -10,7 +10,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTh
     
     interface A<T, U> { // error
               ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
         y: T;
     }
     
@@ -21,7 +21,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTh
     
         interface A<T, U> { // error
                   ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
             y: T;
         }
     }
@@ -47,7 +47,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTh
     module M3 {
         export interface A<T, U> { // error
                          ~
-!!! error TS2428: All declarations of an interface must have identical type parameters.
+!!! error TS2428: All declarations must have identical type parameters.
             y: T;
         }
     }
\ No newline at end of file

From 14a457e51857c8a668560b430d5d923c0b25eb2d Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Fri, 19 Feb 2016 13:05:19 -0800
Subject: [PATCH 4/5] Address review comments

1. Give class name in error message.
2. Reduce nesting via an early exit.
---
 src/compiler/checker.ts              | 19 ++++++++++---------
 src/compiler/diagnosticMessages.json |  2 +-
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index b9a8ab6cd2c..dbce5f41ef4 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -14033,16 +14033,17 @@ namespace ts {
 
         /** Check that type parameter lists are identical across multiple declarations */
         function checkTypeParameterListsIdentical(node: ClassLikeDeclaration | InterfaceDeclaration, symbol: Symbol) {
+            if (symbol.declarations.length === 1) {
+                return;
+            }
             let firstDecl: ClassLikeDeclaration | InterfaceDeclaration;
-            if (symbol.declarations.length > 1) {
-                for (const declaration of symbol.declarations) {
-                    if (declaration.kind === SyntaxKind.ClassDeclaration || declaration.kind === SyntaxKind.InterfaceDeclaration) {
-                        if (!firstDecl) {
-                            firstDecl = <ClassLikeDeclaration | InterfaceDeclaration>declaration;
-                        }
-                        else if (!areTypeParametersIdentical(firstDecl.typeParameters, node.typeParameters)) {
-                            error(node.name, Diagnostics.All_declarations_must_have_identical_type_parameters);
-                        }
+            for (const declaration of symbol.declarations) {
+                if (declaration.kind === SyntaxKind.ClassDeclaration || declaration.kind === SyntaxKind.InterfaceDeclaration) {
+                    if (!firstDecl) {
+                        firstDecl = <ClassLikeDeclaration | InterfaceDeclaration>declaration;
+                    }
+                    else if (!areTypeParametersIdentical(firstDecl.typeParameters, node.typeParameters)) {
+                        error(node.name, Diagnostics.All_declarations_of_0_must_have_identical_type_parameters, node.name.text);
                     }
                 }
             }
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 92396d005b7..70c6d8ff167 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1311,7 +1311,7 @@
         "category": "Error",
         "code": 2427
     },
-    "All declarations must have identical type parameters.": {
+    "All declarations of '{0}' must have identical type parameters.": {
         "category": "Error",
         "code": 2428
     },

From 09ac720382c29dd8c051975ef9c4ed4c22821f4c Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Fri, 19 Feb 2016 13:22:57 -0800
Subject: [PATCH 5/5] Rebaseline tests with improved error message

---
 ...nstructSignaturesWithOverloads2.errors.txt |  4 +-
 ...acesWithDuplicateTypeParameters.errors.txt |  4 +-
 ...GenericInterfaceWithTheSameName.errors.txt | 12 ++---
 ...terfaceWithMultipleDeclarations.errors.txt | 44 +++++++++----------
 .../multipleNumericIndexers.errors.txt        |  4 +-
 .../nonIdenticalTypeConstraints.errors.txt    | 12 ++---
 ...cesDifferingByTypeParameterName.errors.txt | 20 ++++-----
 ...esDifferingByTypeParameterName2.errors.txt | 12 ++---
 ...erfacesWithDifferentConstraints.errors.txt | 12 ++---
 ...ithTheSameNameButDifferentArity.errors.txt | 12 ++---
 10 files changed, 68 insertions(+), 68 deletions(-)

diff --git a/tests/baselines/reference/constructSignaturesWithOverloads2.errors.txt b/tests/baselines/reference/constructSignaturesWithOverloads2.errors.txt
index 4f0a5944659..617f7b1502f 100644
--- a/tests/baselines/reference/constructSignaturesWithOverloads2.errors.txt
+++ b/tests/baselines/reference/constructSignaturesWithOverloads2.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/conformance/types/objectTypeLiteral/constructSignatures/constructSignaturesWithOverloads2.ts(32,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/types/objectTypeLiteral/constructSignatures/constructSignaturesWithOverloads2.ts(32,11): error TS2428: All declarations of 'I' must have identical type parameters.
 
 
 ==== tests/cases/conformance/types/objectTypeLiteral/constructSignatures/constructSignaturesWithOverloads2.ts (1 errors) ====
@@ -35,7 +35,7 @@ tests/cases/conformance/types/objectTypeLiteral/constructSignatures/constructSig
     
     interface I<T> {
               ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'I' must have identical type parameters.
         new (x: T, y?: number): C2<T>;
         new (x: T, y: number): C2<T>;
     }
diff --git a/tests/baselines/reference/extendedInterfacesWithDuplicateTypeParameters.errors.txt b/tests/baselines/reference/extendedInterfacesWithDuplicateTypeParameters.errors.txt
index ebe2cd05aec..7b47fee05af 100644
--- a/tests/baselines/reference/extendedInterfacesWithDuplicateTypeParameters.errors.txt
+++ b/tests/baselines/reference/extendedInterfacesWithDuplicateTypeParameters.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts(1,42): error TS2300: Duplicate identifier 'A'.
-tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts(9,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts(9,11): error TS2428: All declarations of 'InterfaceWithSomeTypars' must have identical type parameters.
 tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts(9,38): error TS2300: Duplicate identifier 'C'.
 
 
@@ -16,7 +16,7 @@ tests/cases/compiler/extendedInterfacesWithDuplicateTypeParameters.ts(9,38): err
     
     interface InterfaceWithSomeTypars<C, C> { // should error
               ~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'InterfaceWithSomeTypars' must have identical type parameters.
                                          ~
 !!! error TS2300: Duplicate identifier 'C'.
     	bar2(): void;
diff --git a/tests/baselines/reference/genericAndNonGenericInterfaceWithTheSameName.errors.txt b/tests/baselines/reference/genericAndNonGenericInterfaceWithTheSameName.errors.txt
index ae02c434d25..8d9ebb8d276 100644
--- a/tests/baselines/reference/genericAndNonGenericInterfaceWithTheSameName.errors.txt
+++ b/tests/baselines/reference/genericAndNonGenericInterfaceWithTheSameName.errors.txt
@@ -1,6 +1,6 @@
-tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(7,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(16,15): error TS2428: All declarations must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(40,22): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(7,11): error TS2428: All declarations of 'A' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(16,15): error TS2428: All declarations of 'A' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts(40,22): error TS2428: All declarations of 'A' must have identical type parameters.
 
 
 ==== tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterfaceWithTheSameName.ts (3 errors) ====
@@ -12,7 +12,7 @@ tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterf
     
     interface A<T> { // error
               ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
         bar: T;
     }
     
@@ -23,7 +23,7 @@ tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterf
     
         interface A { // error
                   ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
             foo: string;
         }
     }
@@ -49,7 +49,7 @@ tests/cases/conformance/interfaces/declarationMerging/genericAndNonGenericInterf
     module M3 {
         export interface A<T> { // error
                          ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
             bar: T;
         }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/interfaceWithMultipleDeclarations.errors.txt b/tests/baselines/reference/interfaceWithMultipleDeclarations.errors.txt
index 5cd4f2f7d96..79d8b4a509a 100644
--- a/tests/baselines/reference/interfaceWithMultipleDeclarations.errors.txt
+++ b/tests/baselines/reference/interfaceWithMultipleDeclarations.errors.txt
@@ -1,14 +1,14 @@
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(3,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(5,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(7,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(9,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(11,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(16,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(18,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(20,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(22,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(24,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/compiler/interfaceWithMultipleDeclarations.ts(29,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(3,11): error TS2428: All declarations of 'I1' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(5,11): error TS2428: All declarations of 'I1' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(7,11): error TS2428: All declarations of 'I1' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(9,11): error TS2428: All declarations of 'I1' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(11,11): error TS2428: All declarations of 'I1' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(16,11): error TS2428: All declarations of 'I2' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(18,11): error TS2428: All declarations of 'I2' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(20,11): error TS2428: All declarations of 'I2' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(22,11): error TS2428: All declarations of 'I2' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(24,11): error TS2428: All declarations of 'I2' must have identical type parameters.
+tests/cases/compiler/interfaceWithMultipleDeclarations.ts(29,11): error TS2428: All declarations of 'I3' must have identical type parameters.
 
 
 ==== tests/cases/compiler/interfaceWithMultipleDeclarations.ts (11 errors) ====
@@ -16,53 +16,53 @@ tests/cases/compiler/interfaceWithMultipleDeclarations.ts(29,11): error TS2428:
     }
     interface I1<S> { // Name mismatch
               ~~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'I1' must have identical type parameters.
     }
     interface I1<T, U extends T> { // Length mismatch
               ~~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'I1' must have identical type parameters.
     }
     interface I1<V extends string> { // constraint present
               ~~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'I1' must have identical type parameters.
     }
     interface I1<V, X extends V> { // Length mismatch
               ~~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'I1' must have identical type parameters.
     }
     interface I1 { // Length mismatch
               ~~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'I1' must have identical type parameters.
     }
     
     interface I2<T extends string> {
     }
     interface I2<T extends () => string> { // constraint mismatch
               ~~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'I2' must have identical type parameters.
     }
     interface I2<T> { // constraint absent
               ~~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'I2' must have identical type parameters.
     }
     interface I2<U> { // name mismatch
               ~~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'I2' must have identical type parameters.
     }
     interface I2<X, Y> { // length mismatch
               ~~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'I2' must have identical type parameters.
     }
     interface I2 { // length mismatch
               ~~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'I2' must have identical type parameters.
     }
     
     interface I3 {
     }
     interface I3<T> { // length mismatch
               ~~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'I3' must have identical type parameters.
     }
     
     class Foo<T> {
diff --git a/tests/baselines/reference/multipleNumericIndexers.errors.txt b/tests/baselines/reference/multipleNumericIndexers.errors.txt
index 11fb81ba5b3..82fc444ac65 100644
--- a/tests/baselines/reference/multipleNumericIndexers.errors.txt
+++ b/tests/baselines/reference/multipleNumericIndexers.errors.txt
@@ -3,7 +3,7 @@ tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericI
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(15,5): error TS2375: Duplicate number index signature.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(20,5): error TS2375: Duplicate number index signature.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(25,5): error TS2375: Duplicate number index signature.
-tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(28,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(28,11): error TS2428: All declarations of 'I' must have identical type parameters.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(29,5): error TS2375: Duplicate number index signature.
 tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericIndexers.ts(30,5): error TS2375: Duplicate number index signature.
 
@@ -48,7 +48,7 @@ tests/cases/conformance/types/objectTypeLiteral/indexSignatures/multipleNumericI
     
     interface I<T> {
               ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'I' must have identical type parameters.
         [x: number]: string;
         ~~~~~~~~~~~~~~~~~~~~
 !!! error TS2375: Duplicate number index signature.
diff --git a/tests/baselines/reference/nonIdenticalTypeConstraints.errors.txt b/tests/baselines/reference/nonIdenticalTypeConstraints.errors.txt
index a8b54bf44dd..627b38579a2 100644
--- a/tests/baselines/reference/nonIdenticalTypeConstraints.errors.txt
+++ b/tests/baselines/reference/nonIdenticalTypeConstraints.errors.txt
@@ -1,6 +1,6 @@
-tests/cases/compiler/nonIdenticalTypeConstraints.ts(10,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/compiler/nonIdenticalTypeConstraints.ts(16,7): error TS2428: All declarations must have identical type parameters.
-tests/cases/compiler/nonIdenticalTypeConstraints.ts(36,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/compiler/nonIdenticalTypeConstraints.ts(10,11): error TS2428: All declarations of 'Foo' must have identical type parameters.
+tests/cases/compiler/nonIdenticalTypeConstraints.ts(16,7): error TS2428: All declarations of 'Qux' must have identical type parameters.
+tests/cases/compiler/nonIdenticalTypeConstraints.ts(36,11): error TS2428: All declarations of 'Quux' must have identical type parameters.
 
 
 ==== tests/cases/compiler/nonIdenticalTypeConstraints.ts (3 errors) ====
@@ -15,7 +15,7 @@ tests/cases/compiler/nonIdenticalTypeConstraints.ts(36,11): error TS2428: All de
     }
     interface Foo<T extends Different> {
               ~~~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'Foo' must have identical type parameters.
         y: T;
     }
     interface Qux<T extends Different> {
@@ -23,7 +23,7 @@ tests/cases/compiler/nonIdenticalTypeConstraints.ts(36,11): error TS2428: All de
     }
     class Qux<T extends Function> {
           ~~~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'Qux' must have identical type parameters.
         n: T;
     }
     
@@ -45,6 +45,6 @@ tests/cases/compiler/nonIdenticalTypeConstraints.ts(36,11): error TS2428: All de
     }
     interface Quux<U> {
               ~~~~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'Quux' must have identical type parameters.
         m: U;
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName.errors.txt b/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName.errors.txt
index 6b56f5dfef6..6c0f562ac64 100644
--- a/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName.errors.txt
+++ b/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName.errors.txt
@@ -1,8 +1,8 @@
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(7,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(15,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(24,15): error TS2428: All declarations must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(32,15): error TS2428: All declarations must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(56,22): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(7,11): error TS2428: All declarations of 'A' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(15,11): error TS2428: All declarations of 'B' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(24,15): error TS2428: All declarations of 'A' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(32,15): error TS2428: All declarations of 'B' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts(56,22): error TS2428: All declarations of 'B' must have identical type parameters.
 
 
 ==== tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName.ts (5 errors) ====
@@ -14,7 +14,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
     interface A<U> { // error
               ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
         y: U;
     }
     
@@ -24,7 +24,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
     interface B<T,V> { // error
               ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'B' must have identical type parameters.
         y: V;
     }
     
@@ -35,7 +35,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
         interface A<U> { // error
                   ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
             y: U;
         }
     
@@ -45,7 +45,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
         interface B<T, V> { // error
                   ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'B' must have identical type parameters.
             y: V;
         }
     }
@@ -71,7 +71,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     module M3 {
         export interface B<T, V> { // error
                          ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'B' must have identical type parameters.
             y: V;
         }
     }
diff --git a/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName2.errors.txt b/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName2.errors.txt
index 7caec272386..f2a0063c230 100644
--- a/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName2.errors.txt
+++ b/tests/baselines/reference/twoGenericInterfacesDifferingByTypeParameterName2.errors.txt
@@ -1,7 +1,7 @@
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(7,11): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(7,11): error TS2428: All declarations of 'B' must have identical type parameters.
 tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(8,8): error TS2304: Cannot find name 'V'.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(16,15): error TS2428: All declarations must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(40,22): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(16,15): error TS2428: All declarations of 'B' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts(40,22): error TS2428: All declarations of 'B' must have identical type parameters.
 
 
 ==== tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDifferingByTypeParameterName2.ts (4 errors) ====
@@ -13,7 +13,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
     interface B<U, T> { // error
               ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'B' must have identical type parameters.
         y: V;
            ~
 !!! error TS2304: Cannot find name 'V'.
@@ -26,7 +26,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     
         interface B<U, T> { // error
                   ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'B' must have identical type parameters.
             y: T;
         }
     }
@@ -52,7 +52,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesDiffer
     module M3 {
         export interface B<U, T> { // error
                          ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'B' must have identical type parameters.
             y: T;
         }
     }
diff --git a/tests/baselines/reference/twoGenericInterfacesWithDifferentConstraints.errors.txt b/tests/baselines/reference/twoGenericInterfacesWithDifferentConstraints.errors.txt
index 39e684ec3dd..4b2455773f5 100644
--- a/tests/baselines/reference/twoGenericInterfacesWithDifferentConstraints.errors.txt
+++ b/tests/baselines/reference/twoGenericInterfacesWithDifferentConstraints.errors.txt
@@ -1,6 +1,6 @@
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(5,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(14,15): error TS2428: All declarations must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(38,22): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(5,11): error TS2428: All declarations of 'A' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(14,15): error TS2428: All declarations of 'B' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts(38,22): error TS2428: All declarations of 'A' must have identical type parameters.
 
 
 ==== tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDifferentConstraints.ts (3 errors) ====
@@ -10,7 +10,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDi
     
     interface A<T extends Number> { // error
               ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
         y: T;
     }
     
@@ -21,7 +21,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDi
     
         interface B<T extends A<any>> { // error
                   ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'B' must have identical type parameters.
             y: T;
         }
     }
@@ -47,7 +47,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithDi
     module M3 {
         export interface A<T extends Number> { // error
                          ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
             y: T;
         }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/twoGenericInterfacesWithTheSameNameButDifferentArity.errors.txt b/tests/baselines/reference/twoGenericInterfacesWithTheSameNameButDifferentArity.errors.txt
index e31a8d5c433..de4c4d8e1c3 100644
--- a/tests/baselines/reference/twoGenericInterfacesWithTheSameNameButDifferentArity.errors.txt
+++ b/tests/baselines/reference/twoGenericInterfacesWithTheSameNameButDifferentArity.errors.txt
@@ -1,6 +1,6 @@
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(5,11): error TS2428: All declarations must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(14,15): error TS2428: All declarations must have identical type parameters.
-tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(38,22): error TS2428: All declarations must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(5,11): error TS2428: All declarations of 'A' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(14,15): error TS2428: All declarations of 'A' must have identical type parameters.
+tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts(38,22): error TS2428: All declarations of 'A' must have identical type parameters.
 
 
 ==== tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTheSameNameButDifferentArity.ts (3 errors) ====
@@ -10,7 +10,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTh
     
     interface A<T, U> { // error
               ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
         y: T;
     }
     
@@ -21,7 +21,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTh
     
         interface A<T, U> { // error
                   ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
             y: T;
         }
     }
@@ -47,7 +47,7 @@ tests/cases/conformance/interfaces/declarationMerging/twoGenericInterfacesWithTh
     module M3 {
         export interface A<T, U> { // error
                          ~
-!!! error TS2428: All declarations must have identical type parameters.
+!!! error TS2428: All declarations of 'A' must have identical type parameters.
             y: T;
         }
     }
\ No newline at end of file