feat(49385): Inlay hint for type of literal-initialized constant is unnecessary

src/services/inlayHints.ts

@@ -121,7 +121,7 @@ namespace ts.InlayHints {
         }
 
         function visitVariableLikeDeclaration(decl: VariableDeclaration | PropertyDeclaration) {
-            if (!decl.initializer || isBindingPattern(decl.name)) {
+            if (!decl.initializer || isBindingPattern(decl.name) || isVariableDeclaration(decl) && !isHintableDeclaration(decl)) {
                 return;
             }
 
@@ -272,8 +272,11 @@ namespace ts.InlayHints {
 
             for (let i = 0; i < node.parameters.length && i < signature.parameters.length; ++i) {
                 const param = node.parameters[i];
-                const effectiveTypeAnnotation = getEffectiveTypeAnnotationNode(param);
+                if (!isHintableDeclaration(param)) {
+                    continue;
+                }
 
+                const effectiveTypeAnnotation = getEffectiveTypeAnnotationNode(param);
                 if (effectiveTypeAnnotation) {
                     continue;
                 }
@@ -323,5 +326,13 @@ namespace ts.InlayHints {
         function isUndefined(name: __String) {
             return name === "undefined";
         }
+
+        function isHintableDeclaration(node: VariableDeclaration | ParameterDeclaration) {
+            if ((isParameterDeclaration(node) || isVariableDeclaration(node) && isVarConst(node)) && node.initializer) {
+                const initializer = skipParentheses(node.initializer);
+                return !(isHintableLiteral(initializer) || isNewExpression(initializer) || isObjectLiteralExpression(initializer) || isAssertionExpression(initializer));
+            }
+            return true;
+        }
     }
 }

tests/cases/fourslash/inlayHintsShouldWork15.ts

@@ -1,15 +1,25 @@
 /// <reference path="fourslash.ts" />
 
-//// const a/*a*/ = 123;
+////class C {}
+////namespace N { export class Foo {} }
+////interface Foo {}
 
-const markers = test.markers();
-verify.getInlayHints([
-    {
-        text: ': 123',
-        position: markers[0].position,
-        kind: ts.InlayHintKind.Type,
-        whitespaceBefore: true
-    },
-], undefined, {
+////const a = "a";
+////const b = 1;
+////const c = true;
+////
+////const d = {} as Foo;
+////const e = <Foo>{};
+////const f = {} as const;
+////const g = (({} as const));
+////
+////const h = new C();
+////const i = new N.C();
+////const j = ((((new C()))));
+////
+////const k = { a: 1, b: 1 };
+////const l = ((({ a: 1, b: 1 })));
+
+verify.getInlayHints([], undefined, {
     includeInlayVariableTypeHints: true
 });

tests/cases/fourslash/inlayHintsShouldWork17.ts

@@ -1,15 +1,7 @@
 /// <reference path="fourslash.ts" />
 
-//// const a/*a*/ = { a: 123 };
+//// const a = { a: 123 };
 
-const markers = test.markers();
-verify.getInlayHints([
-    {
-        text: ': { a: number; }',
-        position: markers[0].position,
-        kind: ts.InlayHintKind.Type,
-        whitespaceBefore: true
-    },
-], undefined, {
+verify.getInlayHints([], undefined, {
     includeInlayVariableTypeHints: true
 });

tests/cases/fourslash/inlayHintsShouldWork18.ts

@@ -1,16 +1,8 @@
 /// <reference path="fourslash.ts" />
 
 //// class Class {}
-//// const a/*a*/ = new Class();
+//// const a = new Class();
 
-const markers = test.markers();
-verify.getInlayHints([
-    {
-        text: ': Class',
-        position: markers[0].position,
-        kind: ts.InlayHintKind.Type,
-        whitespaceBefore: true
-    },
-], undefined, {
+verify.getInlayHints([], undefined, {
     includeInlayVariableTypeHints: true
 });

tests/cases/fourslash/inlayHintsShouldWork22.ts

@@ -1,15 +1,7 @@
 /// <reference path="fourslash.ts" />
 
-//// const a/*a*/ = "I'm very very very very very very very very very long";
+////const a = "I'm very very very very very very very very very long";
 
-const markers = test.markers();
-verify.getInlayHints([
-    {
-        text: `: "I'm very very very very ve...`,
-        position: markers[0].position,
-        kind: ts.InlayHintKind.Type,
-        whitespaceBefore: true
-    },
-], undefined, {
+verify.getInlayHints([], undefined, {
     includeInlayVariableTypeHints: true
 });

tests/cases/fourslash/inlayHintsShouldWork56.ts

@@ -1,37 +1,31 @@
 /// <reference path="fourslash.ts" />
 
-//// const object/*a*/ = { foo: 1, bar: 2 }
-//// const array/*b*/ = [1, 2]
-//// const a/*c*/ = object;
+//// const object = { foo: 1, bar: 2 }
+//// const array/*a*/ = [1, 2]
+//// const a/*b*/ = object;
 //// const { foo, bar } = object;
 //// const {} = object;
-//// const b/*d*/ = array;
+//// const b/*c*/ = array;
 //// const [ first, second ] = array;
 //// const [] = array;
 
 const markers = test.markers();
 verify.getInlayHints([
-    {
-        text: ': { foo: number; bar: number; }',
-        position: markers[0].position,
-        kind: ts.InlayHintKind.Type,
-        whitespaceBefore: true
-    },
     {
         text: ': number[]',
-        position: markers[1].position,
+        position: markers[0].position,
         kind: ts.InlayHintKind.Type,
         whitespaceBefore: true
     },
     {
         text: ': { foo: number; bar: number; }',
-        position: markers[2].position,
+        position: markers[1].position,
         kind: ts.InlayHintKind.Type,
         whitespaceBefore: true
     },
     {
         text: ': number[]',
-        position: markers[3].position,
+        position: markers[2].position,
         kind: ts.InlayHintKind.Type,
         whitespaceBefore: true
     }

tests/cases/fourslash/inlayHintsShouldWork65.ts

@@ -1,21 +1,15 @@
 /// <reference path="fourslash.ts" />
 
 //// type F = (a: string, b: number) => void
-//// const f: F = (a/*a*/,  b/*b*/ = 1) => { }
+//// const f: F = (a/*a*/, b = 1) => { }
 
-const [a, b] = test.markers();
+const [a] = test.markers();
 verify.getInlayHints([
     {
         text: ': string',
         position: a.position,
         kind: ts.InlayHintKind.Type,
         whitespaceBefore: true
-    },
-    {
-        text: ': number',
-        position: b.position,
-        kind: ts.InlayHintKind.Type,
-        whitespaceBefore: true
     }
 ], undefined, {
     includeInlayFunctionParameterTypeHints: true

tests/cases/fourslash/inlayHintsShouldWork69.ts

@@ -0,0 +1,25 @@
+/// <reference path="fourslash.ts" />
+
+////class C {}
+////namespace N { export class Foo {} }
+////interface Foo {}
+
+////function f1(a = 1) {}
+////function f2(a = "a") {}
+////function f3(a = true) {}
+
+////function f4(a = { } as Foo) {}
+////function f5(a = <Foo>{}) {}
+////function f6(a = {} as const) {}
+////function f7(a = (({} as const))) {}
+
+////function f8(a = new C()) {}
+////function f9(a = new N.C()) {}
+////function f10(a = ((((new C()))))) {}
+
+////function f11(a = { a: 1, b: 1 }) {}
+////function f12(a = ((({ a: 1, b: 1 })))) {}
+
+verify.getInlayHints([], undefined, {
+    includeInlayFunctionParameterTypeHints: true
+});