For { type: "a" } | { type: "b" }, find references for the union property (microsoft#21298)

Andy · web-flow · commit 6224d51f84cc · 2018-01-19T16:04:30.000-08:00
diff --git a/src/services/findAllReferences.ts b/src/services/findAllReferences.ts
@@ -356,7 +356,7 @@ namespace ts.FindAllReferences.Core {
 
     /** Core find-all-references algorithm for a normal symbol. */
     function getReferencedSymbolsForSymbol(symbol: Symbol, node: Node, sourceFiles: ReadonlyArray<SourceFile>, checker: TypeChecker, cancellationToken: CancellationToken, options: Options): SymbolAndEntries[] {
-        symbol = skipPastExportOrImportSpecifier(symbol, node, checker);
+        symbol = skipPastExportOrImportSpecifierOrUnion(symbol, node, checker);
 
         // Compute the meaning from the location and the symbol it references
         const searchMeaning = getIntersectingMeaningFromDeclarations(getMeaningFromLocation(node), symbol.declarations);
@@ -405,7 +405,7 @@ namespace ts.FindAllReferences.Core {
     }
 
     /** Handle a few special cases relating to export/import specifiers. */
-    function skipPastExportOrImportSpecifier(symbol: Symbol, node: Node, checker: TypeChecker): Symbol {
+    function skipPastExportOrImportSpecifierOrUnion(symbol: Symbol, node: Node, checker: TypeChecker): Symbol {
         const { parent } = node;
         if (isExportSpecifier(parent)) {
             return getLocalSymbolForExportSpecifier(node as Identifier, symbol, parent, checker);
@@ -415,7 +415,11 @@ namespace ts.FindAllReferences.Core {
             return checker.getImmediateAliasedSymbol(symbol);
         }
 
-        return symbol;
+        // If the symbol is declared as part of a declaration like `{ type: "a" } | { type: "b" }`, use the property on the union type to get more references.
+        return firstDefined(symbol.declarations, decl =>
+            isTypeLiteralNode(decl.parent) && isUnionTypeNode(decl.parent.parent)
+                ? checker.getPropertyOfType(checker.getTypeFromTypeNode(decl.parent.parent), symbol.name)
+                : undefined) || symbol;
     }
 
     /**
diff --git a/tests/cases/fourslash/findAllRefsUnionProperty.ts b/tests/cases/fourslash/findAllRefsUnionProperty.ts
@@ -0,0 +1,16 @@
+/// <reference path='fourslash.ts'/>
+
+////type T =
+////    | { [|{| "isWriteAccess": true, "isDefinition": true |}type|]: "a" }
+////    | { [|{| "isWriteAccess": true, "isDefinition": true |}type|]: "b" };
+////declare const t: T;
+////if (t.[|type|] !== "failure") {
+////    t.[|type|];
+////}
+
+const ranges = test.ranges();
+const [r0, r1, r2, r3] = ranges;
+verify.referenceGroups(ranges, [
+    { definition: '(property) type: "a"', ranges: [r0, r2, r3] }, // TODO: this have type `"a" | "b"`
+    { definition: '(property) type: "b"', ranges: [r1] },
+]);
