Unused identifiers compiler code

src/compiler/checker.ts

@@ -14447,10 +14447,8 @@ namespace ts {
                                 error(local.valueDeclaration, Diagnostics._0_is_declared_but_never_used, key);
                             }
                             else if (local.valueDeclaration.kind === SyntaxKind.Parameter && compilerOptions.noUnusedParameters) {
-                                if (local.valueDeclaration.modifiers) {
-                                    if (getCombinedNodeFlags(local.valueDeclaration) & NodeFlags.Private) {
-                                        error(local.valueDeclaration, Diagnostics._0_is_declared_but_never_used, key);
-                                    }
+                                if (getCombinedNodeFlags(local.valueDeclaration) & NodeFlags.Private) {
+                                    error(local.valueDeclaration, Diagnostics._0_is_declared_but_never_used, key);
                                 }
                                 else {
                                     error(local.valueDeclaration, Diagnostics._0_is_declared_but_never_used, key);
@@ -14462,7 +14460,7 @@ namespace ts {
             }
         }
 
-        function checkUnusedModuleLocals(node: ModuleDeclaration): void {
+        function checkUnusedModuleLocals(node: ModuleDeclaration | SourceFile): void {
             if (compilerOptions.noUnusedLocals && !isInAmbientContext(node)) {
                 for (const key in node.locals) {
                     if (hasProperty(node.locals, key)) {
@@ -14471,13 +14469,12 @@ namespace ts {
                             if ((local.valueDeclaration && local.valueDeclaration.kind)) {
                                 error(local.valueDeclaration, Diagnostics._0_is_declared_but_never_used, key);
                             }
-                            else if (local.declarations &&
-                                (local.declarations[0].kind === SyntaxKind.InterfaceDeclaration || local.declarations[0].kind === SyntaxKind.ModuleDeclaration)) {
-                                error(local.declarations[0], Diagnostics._0_is_declared_but_never_used, key);
-                            }
                             else if (local.declarations && local.declarations[0].kind === SyntaxKind.ImportEqualsDeclaration) {
                                 error(local.declarations[0].name, Diagnostics._0_is_declared_but_never_used, key);
                             }
+                            else if (local.declarations) {
+                                error(local.declarations[0], Diagnostics._0_is_declared_but_never_used, key);
+                            }
                         }
                     }
                 }
@@ -14498,7 +14495,7 @@ namespace ts {
             }
         }
 
-        function checkUnusedTypeParameters(node: ClassDeclaration | FunctionDeclaration | MethodDeclaration | FunctionExpression | ArrowFunction | ConstructorDeclaration | SignatureDeclaration) {
+        function checkUnusedTypeParameters(node: ClassDeclaration | FunctionDeclaration | MethodDeclaration | FunctionExpression | ArrowFunction | ConstructorDeclaration | SignatureDeclaration | InterfaceDeclaration) {
             if (compilerOptions.noUnusedLocals && !isInAmbientContext(node)) {
                 if (node.typeParameters) {
                     for (const typeParameter of node.typeParameters) {
@@ -14520,15 +14517,13 @@ namespace ts {
                     if (hasProperty(node.locals, local)) {
                         const localValue = node.locals[local];
                         if (localValue.declarations && !localValue.exportSymbol) {
-                            for (const declaration of localValue.declarations) {
-                                const symbol = declaration.symbol;
-                                if (!symbol.hasReference) {
-                                    if (declaration.kind === SyntaxKind.ImportSpecifier || declaration.kind === SyntaxKind.ImportClause || declaration.kind === SyntaxKind.NamespaceImport) {
-                                        error(declaration, Diagnostics._0_is_declared_but_never_used, symbol.name);
-                                    }
-                                    else if (declaration.kind === SyntaxKind.ImportEqualsDeclaration) {
-                                        error(declaration.name, Diagnostics._0_is_declared_but_never_used, symbol.name);
-                                    }
+                            const declaration = localValue.declarations[0];
+                            if (!localValue.hasReference) {
+                                if (declaration.kind === SyntaxKind.ImportSpecifier || declaration.kind === SyntaxKind.ImportClause || declaration.kind === SyntaxKind.NamespaceImport) {
+                                    error(declaration, Diagnostics._0_is_declared_but_never_used, localValue.name);
+                                }
+                                else if (declaration.kind === SyntaxKind.ImportEqualsDeclaration) {
+                                    error(declaration.name, Diagnostics._0_is_declared_but_never_used, localValue.name);
                                 }
                             }
                         }
@@ -16010,6 +16005,7 @@ namespace ts {
 
             if (produceDiagnostics) {
                 checkTypeForDuplicateIndexSignatures(node);
+                checkUnusedTypeParameters(node);
             }
         }
 
@@ -16934,6 +16930,7 @@ namespace ts {
                 forEach(node.statements, checkSourceElement);
                 if (isExternalModule(node)) {
                     checkUnusedImports(node);
+                    checkUnusedModuleLocals(node);
                 }
                 checkDeferredNodes();
                 deferredNodes = undefined;

tests/baselines/reference/unusedTypeParameterInInterface1.errors.txt

@@ -0,0 +1,10 @@
+tests/cases/compiler/unusedTypeParameterInInterface1.ts(2,15): error TS6133: 'T' is declared but never used.
+
+
+==== tests/cases/compiler/unusedTypeParameterInInterface1.ts (1 errors) ====
+
+    interface int<T> {
+                  ~
+!!! error TS6133: 'T' is declared but never used.
+
+    }

tests/baselines/reference/unusedTypeParameterInInterface1.js

@@ -0,0 +1,7 @@
+//// [unusedTypeParameterInInterface1.ts]
+
+interface int<T> {
+
+}
+
+//// [unusedTypeParameterInInterface1.js]

tests/baselines/reference/unusedTypeParameterInInterface2.errors.txt

@@ -0,0 +1,11 @@
+tests/cases/compiler/unusedTypeParameterInInterface2.ts(2,18): error TS6133: 'U' is declared but never used.
+
+
+==== tests/cases/compiler/unusedTypeParameterInInterface2.ts (1 errors) ====
+
+    interface int<T, U, V> {
+                     ~
+!!! error TS6133: 'U' is declared but never used.
+        f1(a: T): string;
+        c: V;
+    }

tests/baselines/reference/unusedTypeParameterInInterface2.js

@@ -0,0 +1,8 @@
+//// [unusedTypeParameterInInterface2.ts]
+
+interface int<T, U, V> {
+    f1(a: T): string;
+    c: V;
+}
+
+//// [unusedTypeParameterInInterface2.js]

tests/baselines/reference/unusedVariablesinModules1.errors.txt

@@ -0,0 +1,12 @@
+tests/cases/compiler/unusedVariablesinModules1.ts(4,5): error TS6133: 'x' is declared but never used.
+
+
+==== tests/cases/compiler/unusedVariablesinModules1.ts (1 errors) ====
+
+    export {};
+
+    var x: string;
+        ~
+!!! error TS6133: 'x' is declared but never used.
+
+    export var y: string;

tests/baselines/reference/unusedVariablesinModules1.js

@@ -0,0 +1,11 @@
+//// [unusedVariablesinModules1.ts]
+
+export {};
+
+var x: string;
+
+export var y: string;
+
+//// [unusedVariablesinModules1.js]
+"use strict";
+var x;

tests/cases/compiler/unusedTypeParameterInInterface1.ts

@@ -0,0 +1,6 @@
+//@noUnusedLocals:true
+//@noUnusedParameters:true
+
+interface int<T> {
+
+}

tests/cases/compiler/unusedTypeParameterInInterface2.ts

@@ -0,0 +1,7 @@
+//@noUnusedLocals:true
+//@noUnusedParameters:true
+
+interface int<T, U, V> {
+    f1(a: T): string;
+    c: V;
+}

tests/cases/compiler/unusedVariablesinModules1.ts

@@ -0,0 +1,8 @@
+//@noUnusedLocals:true
+//@noUnusedParameters:true
+
+export {};
+
+var x: string;
+
+export var y: string;