From 8894915d1ac3334716c703403ecf35e8c8e0e1d2 Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Thu, 18 May 2017 10:15:37 -0700
Subject: [PATCH 1/2] buildSymbolDisplay: Handle alias parentSymbol

---
 src/compiler/checker.ts                          |  6 +++---
 .../fourslash/quickInfoOnMethodOfImportEquals.ts | 16 ++++++++++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)
 create mode 100644 tests/cases/fourslash/quickInfoOnMethodOfImportEquals.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index dde8033d1e9..aeabf816a96 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -2027,7 +2027,7 @@ namespace ts {
                                 ts.forEach(symbolFromSymbolTable.declarations, isExternalModuleImportEqualsDeclaration)) {
 
                                 const resolvedImportedSymbol = resolveAlias(symbolFromSymbolTable);
-                                if (isAccessible(symbolFromSymbolTable, resolveAlias(symbolFromSymbolTable))) {
+                                if (isAccessible(symbolFromSymbolTable, resolvedImportedSymbol)) {
                                     return [symbolFromSymbolTable];
                                 }
 
@@ -3087,8 +3087,8 @@ namespace ts {
                         // Write type arguments of instantiated class/interface here
                         if (flags & SymbolFormatFlags.WriteTypeParametersOrArguments) {
                             if (getCheckFlags(symbol) & CheckFlags.Instantiated) {
-                                buildDisplayForTypeArgumentsAndDelimiters(getTypeParametersOfClassOrInterface(parentSymbol),
-                                    (<TransientSymbol>symbol).mapper, writer, enclosingDeclaration);
+                                const params = getTypeParametersOfClassOrInterface(symbol.flags & SymbolFlags.Alias ? resolveAlias(symbol) : symbol);
+                                buildDisplayForTypeArgumentsAndDelimiters(params, (<TransientSymbol>symbol).mapper, writer, enclosingDeclaration);
                             }
                             else {
                                 buildTypeParameterDisplayFromSymbol(parentSymbol, writer, enclosingDeclaration);
diff --git a/tests/cases/fourslash/quickInfoOnMethodOfImportEquals.ts b/tests/cases/fourslash/quickInfoOnMethodOfImportEquals.ts
new file mode 100644
index 00000000000..d4078020add
--- /dev/null
+++ b/tests/cases/fourslash/quickInfoOnMethodOfImportEquals.ts
@@ -0,0 +1,16 @@
+/// <reference path="fourslash.ts" />
+
+// Test for https://github.com/Microsoft/TypeScript/issues/15931
+
+// @Filename: /a.d.ts
+////declare class C<T> {
+////    m(): void;
+////}
+////export = C;
+
+// @Filename: /b.ts
+////import C = require("./a");
+////declare var x: C<number>;
+////x./**/m;
+
+verify.quickInfoAt("", "(method) C<number>.m(): void", undefined);

From bf7e3229cfb7a824f55ab23c03d06e8329e78946 Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Tue, 23 May 2017 09:12:03 -0700
Subject: [PATCH 2/2] Fix typo: symbol -> parentSymbol

---
 src/compiler/checker.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index aeabf816a96..8df64ef4356 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -3087,7 +3087,7 @@ namespace ts {
                         // Write type arguments of instantiated class/interface here
                         if (flags & SymbolFormatFlags.WriteTypeParametersOrArguments) {
                             if (getCheckFlags(symbol) & CheckFlags.Instantiated) {
-                                const params = getTypeParametersOfClassOrInterface(symbol.flags & SymbolFlags.Alias ? resolveAlias(symbol) : symbol);
+                                const params = getTypeParametersOfClassOrInterface(parentSymbol.flags & SymbolFlags.Alias ? resolveAlias(parentSymbol) : parentSymbol);
                                 buildDisplayForTypeArgumentsAndDelimiters(params, (<TransientSymbol>symbol).mapper, writer, enclosingDeclaration);
                             }
                             else {