Unwrap parens when checking for JSDocFunctionType in conditional expression (microsoft#46962)

Author: jakebailey

src/compiler/parser.ts

@@ -4539,10 +4539,16 @@ namespace ts {
             //  - "(x,y)" is a comma expression parsed as a signature with two parameters.
             //  - "a ? (b): c" will have "(b):" parsed as a signature with a return type annotation.
             //  - "a ? (b): function() {}" will too, since function() is a valid JSDoc function type.
-            //  - "a ? (b): (function() {})" as well, but inside of a parenthesized type.
+            //  - "a ? (b): (function() {})" as well, but inside of a parenthesized type with an arbitrary amount of nesting.
             //
             // So we need just a bit of lookahead to ensure that it can only be a signature.
-            const hasJSDocFunctionType = type && (isJSDocFunctionType(type) || isParenthesizedTypeNode(type) && isJSDocFunctionType(type.type));
+
+            let unwrappedType = type;
+            while (unwrappedType?.kind === SyntaxKind.ParenthesizedType) {
+                unwrappedType = (unwrappedType as ParenthesizedTypeNode).type;  // Skip parens if need be
+            }
+
+            const hasJSDocFunctionType = unwrappedType && isJSDocFunctionType(unwrappedType);
             if (!allowAmbiguity && token() !== SyntaxKind.EqualsGreaterThanToken && (hasJSDocFunctionType || token() !== SyntaxKind.OpenBraceToken)) {
                 // Returning undefined here will cause our caller to rewind to where we started from.
                     return undefined;

tests/baselines/reference/parserParenthesizedVariableAndParenthesizedFunctionInTernary.js

@@ -1,8 +1,10 @@
 //// [parserParenthesizedVariableAndParenthesizedFunctionInTernary.ts]
 let a: any;
 const c = true ? (a) : (function() {});
+const d = true ? (a) : ((function() {}));
 
 
 //// [parserParenthesizedVariableAndParenthesizedFunctionInTernary.js]
 var a;
 var c = true ? (a) : (function () { });
+var d = true ? (a) : ((function () { }));

tests/baselines/reference/parserParenthesizedVariableAndParenthesizedFunctionInTernary.symbols

@@ -6,3 +6,7 @@ const c = true ? (a) : (function() {});
 >c : Symbol(c, Decl(parserParenthesizedVariableAndParenthesizedFunctionInTernary.ts, 1, 5))
 >a : Symbol(a, Decl(parserParenthesizedVariableAndParenthesizedFunctionInTernary.ts, 0, 3))
 
+const d = true ? (a) : ((function() {}));
+>d : Symbol(d, Decl(parserParenthesizedVariableAndParenthesizedFunctionInTernary.ts, 2, 5))
+>a : Symbol(a, Decl(parserParenthesizedVariableAndParenthesizedFunctionInTernary.ts, 0, 3))
+

tests/baselines/reference/parserParenthesizedVariableAndParenthesizedFunctionInTernary.types

@@ -11,3 +11,13 @@ const c = true ? (a) : (function() {});
 >(function() {}) : () => void
 >function() {} : () => void
 
+const d = true ? (a) : ((function() {}));
+>d : any
+>true ? (a) : ((function() {})) : any
+>true : true
+>(a) : any
+>a : any
+>((function() {})) : () => void
+>(function() {}) : () => void
+>function() {} : () => void
+

tests/cases/conformance/parser/ecmascript5/parserParenthesizedVariableAndParenthesizedFunctionInTernary.ts

@@ -1,2 +1,3 @@
 let a: any;
 const c = true ? (a) : (function() {});
+const d = true ? (a) : ((function() {}));