Add disableImportOptimizations compiler option

src/compiler/commandLineParser.ts

@@ -588,6 +588,12 @@ namespace ts {
             category: Diagnostics.Module_Resolution_Options,
             description: Diagnostics.Do_not_resolve_the_real_path_of_symlinks,
         },
+        {
+            name: "disableImportOptimizations",
+            type: "boolean",
+            category: Diagnostics.Module_Resolution_Options,
+            description: Diagnostics.Do_not_optimize_imports,
+        },
 
         // Source Maps
         {

src/compiler/diagnosticMessages.json

@@ -4072,6 +4072,10 @@
         "category": "Message",
         "code": 6381
     },
+    "Do not optimize imports": {
+        "category": "Message",
+        "code": 6382
+    },
 
     "The expected type comes from property '{0}' which is declared here on type '{1}'": {
         "category": "Message",

src/compiler/transformers/ts.ts

@@ -3049,6 +3049,10 @@ namespace ts {
          * @param node The import declaration node.
          */
         function visitImportDeclaration(node: ImportDeclaration): VisitResult<Statement> {
+            if (compilerOptions.disableImportOptimizations) {
+                return node;
+            }
+
             if (!node.importClause) {
                 // Do not elide a side-effect only import declaration.
                 //  import "foo";
@@ -3073,6 +3077,10 @@ namespace ts {
          * @param node The import clause node.
          */
         function visitImportClause(node: ImportClause): VisitResult<ImportClause> {
+            if (compilerOptions.disableImportOptimizations) {
+                return node;
+            }
+
             // Elide the import clause if we elide both its name and its named bindings.
             const name = resolver.isReferencedAliasDeclaration(node) ? node.name : undefined;
             const namedBindings = visitNode(node.namedBindings, visitNamedImportBindings, isNamedImportBindings);
@@ -3085,6 +3093,10 @@ namespace ts {
          * @param node The named import bindings node.
          */
         function visitNamedImportBindings(node: NamedImportBindings): VisitResult<NamedImportBindings> {
+            if (compilerOptions.disableImportOptimizations) {
+                return node;
+            }
+
             if (node.kind === SyntaxKind.NamespaceImport) {
                 // Elide a namespace import if it is not referenced.
                 return resolver.isReferencedAliasDeclaration(node) ? node : undefined;
@@ -3102,6 +3114,10 @@ namespace ts {
          * @param node The import specifier node.
          */
         function visitImportSpecifier(node: ImportSpecifier): VisitResult<ImportSpecifier> {
+            if (compilerOptions.disableImportOptimizations) {
+                return node;
+            }
+
             // Elide an import specifier if it is not referenced.
             return resolver.isReferencedAliasDeclaration(node) ? node : undefined;
         }
@@ -3113,6 +3129,10 @@ namespace ts {
          * @param node The export assignment node.
          */
         function visitExportAssignment(node: ExportAssignment): VisitResult<Statement> {
+            if (compilerOptions.disableImportOptimizations) {
+                return node;
+            }
+
             // Elide the export assignment if it does not reference a value.
             return resolver.isValueAliasDeclaration(node)
                 ? visitEachChild(node, visitor, context)

tests/baselines/reference/disableImportOptimizations.js

@@ -0,0 +1,42 @@
+//// [tests/cases/compiler/disableImportOptimizations.ts] ////
+
+//// [disableImportOptimizations1.ts]
+export class ClassWithSideEffect {
+  static someValue = ClassWithSideEffect.initValue();
+
+  static initValue(): string {
+    console.log("We have a side-effect here!");
+    return "something";
+  }
+}
+
+//// [disableImportOptimizations2.ts]
+import { ClassWithSideEffect } from "./disableImportOptimizations1"; //Import gets removed without disableImportOptimizations
+
+export class OtherClass {
+}
+
+//// [disableImportOptimizations1.js]
+"use strict";
+exports.__esModule = true;
+var ClassWithSideEffect = /** @class */ (function () {
+    function ClassWithSideEffect() {
+    }
+    ClassWithSideEffect.initValue = function () {
+        console.log("We have a side-effect here!");
+        return "something";
+    };
+    ClassWithSideEffect.someValue = ClassWithSideEffect.initValue();
+    return ClassWithSideEffect;
+}());
+exports.ClassWithSideEffect = ClassWithSideEffect;
+//// [disableImportOptimizations2.js]
+"use strict";
+exports.__esModule = true;
+var disableImportOptimizations1_1 = require("./disableImportOptimizations1"); //Import gets removed without disableImportOptimizations
+var OtherClass = /** @class */ (function () {
+    function OtherClass() {
+    }
+    return OtherClass;
+}());
+exports.OtherClass = OtherClass;

tests/baselines/reference/disableImportOptimizations.symbols

@@ -0,0 +1,29 @@
+=== tests/cases/compiler/disableImportOptimizations1.ts ===
+export class ClassWithSideEffect {
+>ClassWithSideEffect : Symbol(ClassWithSideEffect, Decl(disableImportOptimizations1.ts, 0, 0))
+
+  static someValue = ClassWithSideEffect.initValue();
+>someValue : Symbol(ClassWithSideEffect.someValue, Decl(disableImportOptimizations1.ts, 0, 34))
+>ClassWithSideEffect.initValue : Symbol(ClassWithSideEffect.initValue, Decl(disableImportOptimizations1.ts, 1, 53))
+>ClassWithSideEffect : Symbol(ClassWithSideEffect, Decl(disableImportOptimizations1.ts, 0, 0))
+>initValue : Symbol(ClassWithSideEffect.initValue, Decl(disableImportOptimizations1.ts, 1, 53))
+
+  static initValue(): string {
+>initValue : Symbol(ClassWithSideEffect.initValue, Decl(disableImportOptimizations1.ts, 1, 53))
+
+    console.log("We have a side-effect here!");
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+
+    return "something";
+  }
+}
+
+=== tests/cases/compiler/disableImportOptimizations2.ts ===
+import { ClassWithSideEffect } from "./disableImportOptimizations1"; //Import gets removed without disableImportOptimizations
+>ClassWithSideEffect : Symbol(ClassWithSideEffect, Decl(disableImportOptimizations2.ts, 0, 8))
+
+export class OtherClass {
+>OtherClass : Symbol(OtherClass, Decl(disableImportOptimizations2.ts, 0, 68))
+}

tests/baselines/reference/disableImportOptimizations.types

@@ -0,0 +1,33 @@
+=== tests/cases/compiler/disableImportOptimizations1.ts ===
+export class ClassWithSideEffect {
+>ClassWithSideEffect : ClassWithSideEffect
+
+  static someValue = ClassWithSideEffect.initValue();
+>someValue : string
+>ClassWithSideEffect.initValue() : string
+>ClassWithSideEffect.initValue : () => string
+>ClassWithSideEffect : typeof ClassWithSideEffect
+>initValue : () => string
+
+  static initValue(): string {
+>initValue : () => string
+
+    console.log("We have a side-effect here!");
+>console.log("We have a side-effect here!") : void
+>console.log : (message?: any, ...optionalParams: any[]) => void
+>console : Console
+>log : (message?: any, ...optionalParams: any[]) => void
+>"We have a side-effect here!" : "We have a side-effect here!"
+
+    return "something";
+>"something" : "something"
+  }
+}
+
+=== tests/cases/compiler/disableImportOptimizations2.ts ===
+import { ClassWithSideEffect } from "./disableImportOptimizations1"; //Import gets removed without disableImportOptimizations
+>ClassWithSideEffect : typeof ClassWithSideEffect
+
+export class OtherClass {
+>OtherClass : OtherClass
+}

tests/baselines/reference/showConfig/Shows tsconfig for single option/disableImportOptimizations/tsconfig.json

@@ -0,0 +1,5 @@
+{
+    "compilerOptions": {
+        "disableImportOptimizations": true
+    }
+}

tests/baselines/reference/tsConfig/Default initialized TSConfig/tsconfig.json

@@ -48,6 +48,7 @@
     // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
     "esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
     // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
+    // "disableImportOptimizations": true,    /* Do not optimize imports */
 
     /* Source Map Options */
     // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */

tests/baselines/reference/tsConfig/Initialized TSConfig with advanced options/tsconfig.json

@@ -48,6 +48,7 @@
     // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
     "esModuleInterop": true,                  /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
     // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
+    // "disableImportOptimizations": true,    /* Do not optimize imports */
 
     /* Source Map Options */
     // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */

tests/baselines/reference/tsConfig/Initialized TSConfig with boolean value compiler options/tsconfig.json

@@ -48,6 +48,7 @@
     // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
     "esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
     // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
+    // "disableImportOptimizations": true,    /* Do not optimize imports */
 
     /* Source Map Options */
     // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */

tests/baselines/reference/tsConfig/Initialized TSConfig with enum value compiler options/tsconfig.json

@@ -48,6 +48,7 @@
     // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
     "esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
     // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
+    // "disableImportOptimizations": true,    /* Do not optimize imports */
 
     /* Source Map Options */
     // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */

tests/baselines/reference/tsConfig/Initialized TSConfig with files options/tsconfig.json

@@ -48,6 +48,7 @@
     // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
     "esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
     // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
+    // "disableImportOptimizations": true,    /* Do not optimize imports */
 
     /* Source Map Options */
     // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */

tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option value/tsconfig.json

@@ -48,6 +48,7 @@
     // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
     "esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
     // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
+    // "disableImportOptimizations": true,    /* Do not optimize imports */
 
     /* Source Map Options */
     // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */

tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option/tsconfig.json

@@ -48,6 +48,7 @@
     // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
     "esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
     // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
+    // "disableImportOptimizations": true,    /* Do not optimize imports */
 
     /* Source Map Options */
     // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */

tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options with enum value/tsconfig.json

@@ -48,6 +48,7 @@
     // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
     "esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
     // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
+    // "disableImportOptimizations": true,    /* Do not optimize imports */
 
     /* Source Map Options */
     // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */

tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options/tsconfig.json

@@ -48,6 +48,7 @@
     // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
     "esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
     // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
+    // "disableImportOptimizations": true,    /* Do not optimize imports */
 
     /* Source Map Options */
     // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */

tests/cases/compiler/disableImportOptimizations.ts

@@ -0,0 +1,17 @@
+// @disableImportOptimizations: true
+
+// @fileName: disableImportOptimizations1.ts
+export class ClassWithSideEffect {
+  static someValue = ClassWithSideEffect.initValue();
+
+  static initValue(): string {
+    console.log("We have a side-effect here!");
+    return "something";
+  }
+}
+
+// @fileName: disableImportOptimizations2.ts
+import { ClassWithSideEffect } from "./disableImportOptimizations1"; //Import gets removed without disableImportOptimizations
+
+export class OtherClass {
+}