From 37d4f6a69d25743b85541b8eb1221da4c670f2a2 Mon Sep 17 00:00:00 2001
From: Andy <anhans@microsoft.com>
Date: Mon, 8 Jan 2018 16:44:58 -0800
Subject: [PATCH] Mark references to dynamically-named properties as used
 (#21010)

* Mark references to dynamically-named properties as used

* Avoid showing the symbol ID

* Use symbolToString instead of showSymbol
---
 src/compiler/checker.ts                       |  6 ++-
 ..._writeOnlyProperty_dynamicNames.errors.txt | 17 ++++++++
 ...edLocals_writeOnlyProperty_dynamicNames.js | 25 ++++++++++++
 ...als_writeOnlyProperty_dynamicNames.symbols | 31 +++++++++++++++
 ...ocals_writeOnlyProperty_dynamicNames.types | 39 +++++++++++++++++++
 ...edLocals_writeOnlyProperty_dynamicNames.ts | 13 +++++++
 6 files changed, 129 insertions(+), 2 deletions(-)
 create mode 100644 tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.errors.txt
 create mode 100644 tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.js
 create mode 100644 tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.symbols
 create mode 100644 tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.types
 create mode 100644 tests/cases/compiler/noUnusedLocals_writeOnlyProperty_dynamicNames.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index c66afe73d91..2b8244ca06c 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -8252,6 +8252,7 @@ namespace ts {
                 const prop = getPropertyOfType(objectType, propName);
                 if (prop) {
                     if (accessExpression) {
+                        markPropertyAsReferenced(prop, accessExpression, /*isThisAccess*/ accessExpression.expression.kind === SyntaxKind.ThisKeyword);
                         if (isAssignmentTarget(accessExpression) && (isReferenceToReadonlyEntity(accessExpression, prop) || isReferenceThroughNamespaceImport(accessExpression))) {
                             error(accessExpression.argumentExpression, Diagnostics.Cannot_assign_to_0_because_it_is_a_constant_or_a_read_only_property, symbolToString(prop));
                             return unknownType;
@@ -21356,8 +21357,9 @@ namespace ts {
                                 // Already would have reported an error on the getter.
                                 break;
                             }
-                            if (!member.symbol.isReferenced && hasModifier(member, ModifierFlags.Private)) {
-                                error(member.name, Diagnostics._0_is_declared_but_its_value_is_never_read, symbolName(member.symbol));
+                            const symbol = getSymbolOfNode(member);
+                            if (!symbol.isReferenced && hasModifier(member, ModifierFlags.Private)) {
+                                error(member.name, Diagnostics._0_is_declared_but_its_value_is_never_read, symbolToString(symbol));
                             }
                             break;
                         case SyntaxKind.Constructor:
diff --git a/tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.errors.txt b/tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.errors.txt
new file mode 100644
index 00000000000..9f95f4cfd2f
--- /dev/null
+++ b/tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.errors.txt
@@ -0,0 +1,17 @@
+tests/cases/compiler/noUnusedLocals_writeOnlyProperty_dynamicNames.ts(4,13): error TS6133: '[x]' is declared but its value is never read.
+
+
+==== tests/cases/compiler/noUnusedLocals_writeOnlyProperty_dynamicNames.ts (1 errors) ====
+    const x = Symbol("x");
+    const y = Symbol("y");
+    class C {
+        private [x]: number;
+                ~~~
+!!! error TS6133: '[x]' is declared but its value is never read.
+        private [y]: number;
+        m() {
+            this[x] = 0; // write-only
+            this[y];
+        }
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.js b/tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.js
new file mode 100644
index 00000000000..6c5bf109b57
--- /dev/null
+++ b/tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.js
@@ -0,0 +1,25 @@
+//// [noUnusedLocals_writeOnlyProperty_dynamicNames.ts]
+const x = Symbol("x");
+const y = Symbol("y");
+class C {
+    private [x]: number;
+    private [y]: number;
+    m() {
+        this[x] = 0; // write-only
+        this[y];
+    }
+}
+
+
+//// [noUnusedLocals_writeOnlyProperty_dynamicNames.js]
+var x = Symbol("x");
+var y = Symbol("y");
+var C = /** @class */ (function () {
+    function C() {
+    }
+    C.prototype.m = function () {
+        this[x] = 0; // write-only
+        this[y];
+    };
+    return C;
+}());
diff --git a/tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.symbols b/tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.symbols
new file mode 100644
index 00000000000..6a30e2a9fa9
--- /dev/null
+++ b/tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.symbols
@@ -0,0 +1,31 @@
+=== tests/cases/compiler/noUnusedLocals_writeOnlyProperty_dynamicNames.ts ===
+const x = Symbol("x");
+>x : Symbol(x, Decl(noUnusedLocals_writeOnlyProperty_dynamicNames.ts, 0, 5))
+>Symbol : Symbol(Symbol, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --))
+
+const y = Symbol("y");
+>y : Symbol(y, Decl(noUnusedLocals_writeOnlyProperty_dynamicNames.ts, 1, 5))
+>Symbol : Symbol(Symbol, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --))
+
+class C {
+>C : Symbol(C, Decl(noUnusedLocals_writeOnlyProperty_dynamicNames.ts, 1, 22))
+
+    private [x]: number;
+>x : Symbol(x, Decl(noUnusedLocals_writeOnlyProperty_dynamicNames.ts, 0, 5))
+
+    private [y]: number;
+>y : Symbol(y, Decl(noUnusedLocals_writeOnlyProperty_dynamicNames.ts, 1, 5))
+
+    m() {
+>m : Symbol(C.m, Decl(noUnusedLocals_writeOnlyProperty_dynamicNames.ts, 4, 24))
+
+        this[x] = 0; // write-only
+>this : Symbol(C, Decl(noUnusedLocals_writeOnlyProperty_dynamicNames.ts, 1, 22))
+>x : Symbol(x, Decl(noUnusedLocals_writeOnlyProperty_dynamicNames.ts, 0, 5))
+
+        this[y];
+>this : Symbol(C, Decl(noUnusedLocals_writeOnlyProperty_dynamicNames.ts, 1, 22))
+>y : Symbol(y, Decl(noUnusedLocals_writeOnlyProperty_dynamicNames.ts, 1, 5))
+    }
+}
+
diff --git a/tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.types b/tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.types
new file mode 100644
index 00000000000..7b173395a99
--- /dev/null
+++ b/tests/baselines/reference/noUnusedLocals_writeOnlyProperty_dynamicNames.types
@@ -0,0 +1,39 @@
+=== tests/cases/compiler/noUnusedLocals_writeOnlyProperty_dynamicNames.ts ===
+const x = Symbol("x");
+>x : unique symbol
+>Symbol("x") : unique symbol
+>Symbol : SymbolConstructor
+>"x" : "x"
+
+const y = Symbol("y");
+>y : unique symbol
+>Symbol("y") : unique symbol
+>Symbol : SymbolConstructor
+>"y" : "y"
+
+class C {
+>C : C
+
+    private [x]: number;
+>x : unique symbol
+
+    private [y]: number;
+>y : unique symbol
+
+    m() {
+>m : () => void
+
+        this[x] = 0; // write-only
+>this[x] = 0 : 0
+>this[x] : number
+>this : this
+>x : unique symbol
+>0 : 0
+
+        this[y];
+>this[y] : number
+>this : this
+>y : unique symbol
+    }
+}
+
diff --git a/tests/cases/compiler/noUnusedLocals_writeOnlyProperty_dynamicNames.ts b/tests/cases/compiler/noUnusedLocals_writeOnlyProperty_dynamicNames.ts
new file mode 100644
index 00000000000..065c6f89e7a
--- /dev/null
+++ b/tests/cases/compiler/noUnusedLocals_writeOnlyProperty_dynamicNames.ts
@@ -0,0 +1,13 @@
+// @noUnusedLocals: true
+// @lib: es6
+
+const x = Symbol("x");
+const y = Symbol("y");
+class C {
+    private [x]: number;
+    private [y]: number;
+    m() {
+        this[x] = 0; // write-only
+        this[y];
+    }
+}