Deprecate alwaysStrict: false (#63089)

Author: RyanCavanaugh

src/compiler/binder.ts

@@ -82,6 +82,7 @@ import {
     FunctionExpression,
     FunctionLikeDeclaration,
     GetAccessorDeclaration,
+    getAlwaysStrict,
     getAssignedExpandoInitializer,
     getAssignmentDeclarationKind,
     getAssignmentDeclarationPropertyAccessKind,
@@ -108,7 +109,6 @@ import {
     getSourceFileOfNode,
     getSourceTextOfNodeFromSourceFile,
     getSpanOfTokenAtPosition,
-    getStrictOptionValue,
     getSymbolNameForPrivateIdentifier,
     getTextOfIdentifierOrLiteral,
     getThisContainer,
@@ -618,7 +618,7 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
     }
 
     function bindInStrictMode(file: SourceFile, opts: CompilerOptions): boolean {
-        if (getStrictOptionValue(opts, "alwaysStrict") && !file.isDeclarationFile) {
+        if (getAlwaysStrict(opts) && !file.isDeclarationFile) {
             // bind in strict mode source files with alwaysStrict option
             return true;
         }

src/compiler/commandLineParser.ts

@@ -987,10 +987,9 @@ const commandOptionsWithoutBuild: CommandLineOption[] = [
         affectsSourceFile: true,
         affectsEmit: true,
         affectsBuildInfo: true,
-        strictFlag: true,
         category: Diagnostics.Type_Checking,
         description: Diagnostics.Ensure_use_strict_is_always_emitted,
-        defaultValueDescription: Diagnostics.false_unless_strict_is_set,
+        defaultValueDescription: true,
     },
 
     // Additional Checks

src/compiler/program.ts

@@ -4526,6 +4526,9 @@ export function createProgram(_rootNamesOrOptions: readonly string[] | CreatePro
         });
 
         checkDeprecations("6.0", "7.0", createDiagnostic, createDeprecatedDiagnostic => {
+            if (options.alwaysStrict === false) {
+                createDeprecatedDiagnostic("alwaysStrict", "false", /*useInstead*/ undefined, /*related*/ undefined);
+            }
             if (options.target === ScriptTarget.ES5) {
                 createDeprecatedDiagnostic("target", "ES5");
             }

src/compiler/transformers/module/module.ts

@@ -41,6 +41,7 @@ import {
     FunctionDeclaration,
     FunctionExpression,
     GeneratedIdentifierFlags,
+    getAlwaysStrict,
     getEmitFlags,
     getEmitModuleKind,
     getEmitScriptTarget,
@@ -55,7 +56,6 @@ import {
     getNamespaceDeclarationNode,
     getNodeId,
     getOriginalNodeId,
-    getStrictOptionValue,
     getTextOfIdentifierOrLiteral,
     hasJSFileExtension,
     hasJsonModuleEmitEnabled,
@@ -277,7 +277,7 @@ export function transformModule(context: TransformationContext): (x: SourceFile
         startLexicalEnvironment();
 
         const statements: Statement[] = [];
-        const ensureUseStrict = getStrictOptionValue(compilerOptions, "alwaysStrict") || isExternalModule(currentSourceFile);
+        const ensureUseStrict = getAlwaysStrict(compilerOptions) || isExternalModule(currentSourceFile);
         const statementOffset = factory.copyPrologue(node.statements, statements, ensureUseStrict && !isJsonSourceFile(node), topLevelVisitor);
 
         if (shouldEmitUnderscoreUnderscoreESModule()) {

src/compiler/transformers/module/system.ts

@@ -33,14 +33,14 @@ import {
     ForOfStatement,
     ForStatement,
     FunctionDeclaration,
+    getAlwaysStrict,
     getEmitFlags,
     getExternalHelpersModuleName,
     getExternalModuleNameLiteral,
     getLocalNameForExternalImport,
     getNodeId,
     getOriginalNode,
     getOriginalNodeId,
-    getStrictOptionValue,
     getTextOfIdentifierOrLiteral,
     hasSyntacticModifier,
     Identifier,
@@ -357,7 +357,7 @@ export function transformSystemModule(context: TransformationContext): (x: Sourc
         startLexicalEnvironment();
 
         // Add any prologue directives.
-        const ensureUseStrict = getStrictOptionValue(compilerOptions, "alwaysStrict") || isExternalModule(currentSourceFile);
+        const ensureUseStrict = getAlwaysStrict(compilerOptions) || isExternalModule(currentSourceFile);
         const statementOffset = factory.copyPrologue(node.statements, statements, ensureUseStrict, topLevelVisitor);
 
         // var __moduleName = context_1 && context_1.id;

src/compiler/transformers/ts.ts

@@ -47,6 +47,7 @@ import {
     FunctionExpression,
     FunctionLikeDeclaration,
     GetAccessorDeclaration,
+    getAlwaysStrict,
     getEffectiveBaseTypeNode,
     getEmitFlags,
     getEmitModuleKind,
@@ -57,7 +58,6 @@ import {
     getOriginalNode,
     getParseTreeNode,
     getProperties,
-    getStrictOptionValue,
     getTextOfNode,
     hasDecorators,
     hasSyntacticModifier,
@@ -836,7 +836,7 @@ export function transformTypeScript(context: TransformationContext): Transformer
     }
 
     function visitSourceFile(node: SourceFile) {
-        const alwaysStrict = getStrictOptionValue(compilerOptions, "alwaysStrict") &&
+        const alwaysStrict = getAlwaysStrict(compilerOptions) &&
             !(isExternalModule(node) && moduleKind >= ModuleKind.ES2015) &&
             !isJsonSourceFile(node);
 

src/compiler/utilities.ts

@@ -2132,7 +2132,7 @@ export function isEffectiveStrictModeSourceFile(node: SourceFile, compilerOption
         return false;
     }
     // If `alwaysStrict` is set, then treat the file as strict.
-    if (getStrictOptionValue(compilerOptions, "alwaysStrict")) {
+    if (getAlwaysStrict(compilerOptions)) {
         return true;
     }
     // Starting with a "use strict" directive indicates the file is strict.
@@ -9212,10 +9212,11 @@ const _computedOptions = createComputedCompilerOptions({
             return getStrictOptionValue(compilerOptions, "strictBuiltinIteratorReturn");
         },
     },
+    // Previously a strict-mode flag, but no longer.
     alwaysStrict: {
-        dependencies: ["strict"],
+        dependencies: [],
         computeValue: compilerOptions => {
-            return getStrictOptionValue(compilerOptions, "alwaysStrict");
+            return compilerOptions.alwaysStrict !== false;
         },
     },
     useUnknownInCatchVariables: {
@@ -9263,6 +9264,8 @@ export const getAreDeclarationMapsEnabled: (compilerOptions: CompilerOptions) =>
 export const getAllowJSCompilerOption: (compilerOptions: CompilerOptions) => boolean = _computedOptions.allowJs.computeValue;
 /** @internal */
 export const getUseDefineForClassFields: (compilerOptions: CompilerOptions) => boolean = _computedOptions.useDefineForClassFields.computeValue;
+/** @internal */
+export const getAlwaysStrict: (compilerOptions: CompilerOptions) => boolean = _computedOptions.alwaysStrict.computeValue;
 
 /** @internal */
 export function emitModuleKindIsNonNodeESM(moduleKind: ModuleKind): boolean {
@@ -9305,7 +9308,6 @@ export type StrictOptionName =
     | "strictBindCallApply"
     | "strictPropertyInitialization"
     | "strictBuiltinIteratorReturn"
-    | "alwaysStrict"
     | "useUnknownInCatchVariables";
 
 /** @internal */

src/testRunner/unittests/tscWatch/programUpdates.ts

@@ -1600,7 +1600,7 @@ foo().hello`,
             },
             {
                 caption: "Set always strict false",
-                edit: sys => sys.writeFile(`/user/username/projects/myproject/tsconfig.json`, jsonToReadableText({ compilerOptions: { strict: true, alwaysStrict: false } })), // Avoid changing 'alwaysStrict' or must re-bind
+                edit: sys => sys.writeFile(`/user/username/projects/myproject/tsconfig.json`, jsonToReadableText({ compilerOptions: { strict: true, alwaysStrict: false, ignoreDeprecations: "6.0" } })), // Avoid changing 'alwaysStrict' or must re-bind
                 timeouts: sys => sys.runQueuedTimeoutCallbacks(),
             },
             {

tests/baselines/reference/ArrowFunction4.js

@@ -6,5 +6,6 @@ var v = (a, b) => {
 };
 
 //// [ArrowFunction4.js]
+"use strict";
 var v = (a, b) => {
 };

tests/baselines/reference/ClassDeclaration10.js

@@ -7,5 +7,6 @@ class C {
 }
 
 //// [ClassDeclaration10.js]
+"use strict";
 class C {
 }