fix(47562): Add option to suppress type hint if variable name matches type name (#48529)

* fix(47562): Add option to suppress type hint if variable name matches type

* Remove the unnecessary debug code

* Re-run gulp runtests

* Use equateStringsCaseInsensitive to compare strings

Author: huytd

src/compiler/types.ts

@@ -8813,6 +8813,7 @@ namespace ts {
         readonly includeInlayParameterNameHintsWhenArgumentMatchesName?: boolean;
         readonly includeInlayFunctionParameterTypeHints?: boolean,
         readonly includeInlayVariableTypeHints?: boolean;
+        readonly includeInlayVariableTypeHintsWhenTypeMatchesName?: boolean;
         readonly includeInlayPropertyDeclarationTypeHints?: boolean;
         readonly includeInlayFunctionLikeReturnTypeHints?: boolean;
         readonly includeInlayEnumMemberValueHints?: boolean;

src/server/protocol.ts

@@ -728,7 +728,7 @@ namespace ts.server.protocol {
     }
 
     // All we need is the `success` and `message` fields of Response.
-    export interface ApplyCodeActionCommandResponse extends Response {}
+    export interface ApplyCodeActionCommandResponse extends Response { }
 
     export interface FileRangeRequestArgs extends FileRequestArgs {
         /**
@@ -1067,7 +1067,7 @@ namespace ts.server.protocol {
         readonly arguments: JsxClosingTagRequestArgs;
     }
 
-    export interface JsxClosingTagRequestArgs extends FileLocationRequestArgs {}
+    export interface JsxClosingTagRequestArgs extends FileLocationRequestArgs { }
 
     export interface JsxClosingTagResponse extends Response {
         readonly body: TextInsertion;
@@ -2390,7 +2390,7 @@ namespace ts.server.protocol {
         /**
          * Human-readable description of the `source` from the CompletionEntry.
          */
-         sourceDisplay?: SymbolDisplayPart[];
+        sourceDisplay?: SymbolDisplayPart[];
     }
 
     /** @deprecated Prefer CompletionInfoResponse, which supports several top-level fields in addition to the array of entries. */
@@ -3415,7 +3415,7 @@ namespace ts.server.protocol {
         /**
          * Allows completions to be formatted with snippet text, indicated by `CompletionItem["isSnippet"]`.
          */
-         readonly includeCompletionsWithSnippetText?: boolean;
+        readonly includeCompletionsWithSnippetText?: boolean;
         /**
          * If enabled, the completion list will include completions with invalid identifier names.
          * For those entries, The `insertText` and `replacementSpan` properties will be set to change from `.x` property access to `["x"]`.
@@ -3465,6 +3465,7 @@ namespace ts.server.protocol {
         readonly includeInlayParameterNameHintsWhenArgumentMatchesName?: boolean;
         readonly includeInlayFunctionParameterTypeHints?: boolean,
         readonly includeInlayVariableTypeHints?: boolean;
+        readonly includeInlayVariableTypeHintsWhenTypeMatchesName?: boolean;
         readonly includeInlayPropertyDeclarationTypeHints?: boolean;
         readonly includeInlayFunctionLikeReturnTypeHints?: boolean;
         readonly includeInlayEnumMemberValueHints?: boolean;

src/services/inlayHints.ts

@@ -137,6 +137,10 @@ namespace ts.InlayHints {
 
             const typeDisplayString = printTypeInSingleLine(declarationType);
             if (typeDisplayString) {
+                const isVariableNameMatchesType = preferences.includeInlayVariableTypeHintsWhenTypeMatchesName === false && equateStringsCaseInsensitive(decl.name.getText(), typeDisplayString);
+                if (isVariableNameMatchesType) {
+                    return;
+                }
                 addTypeHints(typeDisplayString, decl.name.end);
             }
         }

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -4120,6 +4120,7 @@ declare namespace ts {
         readonly includeInlayParameterNameHintsWhenArgumentMatchesName?: boolean;
         readonly includeInlayFunctionParameterTypeHints?: boolean;
         readonly includeInlayVariableTypeHints?: boolean;
+        readonly includeInlayVariableTypeHintsWhenTypeMatchesName?: boolean;
         readonly includeInlayPropertyDeclarationTypeHints?: boolean;
         readonly includeInlayFunctionLikeReturnTypeHints?: boolean;
         readonly includeInlayEnumMemberValueHints?: boolean;
@@ -9711,6 +9712,7 @@ declare namespace ts.server.protocol {
         readonly includeInlayParameterNameHintsWhenArgumentMatchesName?: boolean;
         readonly includeInlayFunctionParameterTypeHints?: boolean;
         readonly includeInlayVariableTypeHints?: boolean;
+        readonly includeInlayVariableTypeHintsWhenTypeMatchesName?: boolean;
         readonly includeInlayPropertyDeclarationTypeHints?: boolean;
         readonly includeInlayFunctionLikeReturnTypeHints?: boolean;
         readonly includeInlayEnumMemberValueHints?: boolean;

tests/baselines/reference/api/typescript.d.ts

@@ -4120,6 +4120,7 @@ declare namespace ts {
         readonly includeInlayParameterNameHintsWhenArgumentMatchesName?: boolean;
         readonly includeInlayFunctionParameterTypeHints?: boolean;
         readonly includeInlayVariableTypeHints?: boolean;
+        readonly includeInlayVariableTypeHintsWhenTypeMatchesName?: boolean;
         readonly includeInlayPropertyDeclarationTypeHints?: boolean;
         readonly includeInlayFunctionLikeReturnTypeHints?: boolean;
         readonly includeInlayEnumMemberValueHints?: boolean;

tests/cases/fourslash/fourslash.ts

@@ -666,6 +666,7 @@ declare namespace FourSlashInterface {
         readonly includeInlayParameterNameHintsWhenArgumentMatchesName?: boolean;
         readonly includeInlayFunctionParameterTypeHints?: boolean;
         readonly includeInlayVariableTypeHints?: boolean;
+        readonly includeInlayVariableTypeHintsWhenTypeMatchesName?: boolean;
         readonly includeInlayPropertyDeclarationTypeHints?: boolean;
         readonly includeInlayFunctionLikeReturnTypeHints?: boolean;
         readonly includeInlayEnumMemberValueHints?: boolean;

tests/cases/fourslash/inlayHintsShouldWork67.ts

@@ -0,0 +1,24 @@
+/// <reference path="fourslash.ts" />
+
+//// type Client = {};
+//// function getClient(): Client { return {}; };
+//// const client/**/ = getClient();
+
+const markers = test.markers();
+
+verify.getInlayHints([
+    {
+        text: ': Client',
+        position: markers[0].position,
+        kind: ts.InlayHintKind.Type,
+        whitespaceBefore: true
+    }
+], undefined, {
+    includeInlayVariableTypeHints: true,
+    includeInlayVariableTypeHintsWhenTypeMatchesName: true
+});
+
+verify.getInlayHints([], undefined, {
+    includeInlayVariableTypeHints: true,
+    includeInlayVariableTypeHintsWhenTypeMatchesName: false
+});