If target:esnext,then useDefineForClassFields: true will now be the d…

…efault.
Nathan Shively-Sanders (sandersn) · Apr 7, 2021 · Feb 4, 2021 · Feb 4, 2021 · Feb 5, 2021 · Feb 5, 2021
commit dc5d50e3d37b37a2ff848205b8e9af655ed0d6e3
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -346,6 +346,7 @@ namespace ts {
         const compilerOptions = host.getCompilerOptions();
         const languageVersion = getEmitScriptTarget(compilerOptions);
         const moduleKind = getEmitModuleKind(compilerOptions);
+        const useDefineForClassFields = getUseDefineForClassFields(compilerOptions);
         const allowSyntheticDefaultImports = getAllowSyntheticDefaultImports(compilerOptions);
         const strictNullChecks = getStrictOptionValue(compilerOptions, "strictNullChecks");
         const strictFunctionTypes = getStrictOptionValue(compilerOptions, "strictFunctionTypes");
@@ -1501,7 +1502,7 @@ namespace ts {
                 }
                 else if (isParameterPropertyDeclaration(declaration, declaration.parent)) {
                     // foo = this.bar is illegal in esnext+useDefineForClassFields when bar is a parameter property
-                    return !(compilerOptions.target === ScriptTarget.ESNext && !!compilerOptions.useDefineForClassFields
+                    return !(compilerOptions.target === ScriptTarget.ESNext && useDefineForClassFields
                              && getContainingClass(declaration) === getContainingClass(usage)
                              && isUsedInFunctionOrInstanceProperty(usage, declaration));
                 }
@@ -1532,7 +1533,7 @@ namespace ts {
                 return true;
             }
             if (isUsedInFunctionOrInstanceProperty(usage, declaration)) {
-                if (compilerOptions.target === ScriptTarget.ESNext && !!compilerOptions.useDefineForClassFields
+                if (compilerOptions.target === ScriptTarget.ESNext && useDefineForClassFields
                     && getContainingClass(declaration)
                     && (isPropertyDeclaration(declaration) || isParameterPropertyDeclaration(declaration, declaration.parent))) {
                     return !isPropertyImmediatelyReferencedWithinDeclaration(declaration, usage, /*stopAtAnyPropertyDeclaration*/ true);
@@ -1680,7 +1681,7 @@ namespace ts {
                     case SyntaxKind.PropertyDeclaration:
                         // static properties in classes introduce temporary variables
                         if (hasStaticModifier(node)) {
-                            return target < ScriptTarget.ESNext || !compilerOptions.useDefineForClassFields;
+                            return target < ScriptTarget.ESNext || !useDefineForClassFields;
                         }
                         return requiresScopeChangeWorker((node as PropertyDeclaration).name);
                     default:
@@ -2098,7 +2099,7 @@ namespace ts {
 
             // Perform extra checks only if error reporting was requested
             if (nameNotFoundMessage) {
-                if (propertyWithInvalidInitializer && !(compilerOptions.target === ScriptTarget.ESNext && compilerOptions.useDefineForClassFields)) {
+                if (propertyWithInvalidInitializer && !(compilerOptions.target === ScriptTarget.ESNext && useDefineForClassFields)) {
                     // We have a match, but the reference occurred within a property initializer and the identifier also binds
                     // to a local variable in the constructor where the code will be emitted. Note that this is actually allowed
                     // with ESNext+useDefineForClassFields because the scope semantics are different.
@@ -24183,7 +24184,7 @@ namespace ts {
                     break;
                 case SyntaxKind.PropertyDeclaration:
                 case SyntaxKind.PropertySignature:
-                    if (hasSyntacticModifier(container, ModifierFlags.Static) && !(compilerOptions.target === ScriptTarget.ESNext && compilerOptions.useDefineForClassFields)) {
+                    if (hasSyntacticModifier(container, ModifierFlags.Static) && !(compilerOptions.target === ScriptTarget.ESNext && useDefineForClassFields)) {
                         error(node, Diagnostics.this_cannot_be_referenced_in_a_static_property_initializer);
                         // do not return here so in case if lexical this is captured - it will be reflected in flags on NodeLinks
                     }
@@ -33054,7 +33055,7 @@ namespace ts {
                     // - The constructor declares parameter properties
                     //   or the containing class declares instance member variables with initializers.
                     const superCallShouldBeFirst =
-                        (compilerOptions.target !== ScriptTarget.ESNext || !compilerOptions.useDefineForClassFields) &&
+                        (compilerOptions.target !== ScriptTarget.ESNext || !useDefineForClassFields) &&
                         (some((<ClassDeclaration>node.parent).members, isInstancePropertyWithInitializerOrPrivateIdentifierProperty) ||
                          some(node.parameters, p => hasSyntacticModifier(p, ModifierFlags.ParameterPropertyModifier)));
 
@@ -37059,7 +37060,7 @@ namespace ts {
                                 Diagnostics._0_is_defined_as_a_property_in_class_1_but_is_overridden_here_in_2_as_an_accessor;
                             error(getNameOfDeclaration(derived.valueDeclaration) || derived.valueDeclaration, errorMessage, symbolToString(base), typeToString(baseType), typeToString(type));
                         }
-                        else if (compilerOptions.useDefineForClassFields) {
+                        else if (useDefineForClassFields) {
                             const uninitialized = derived.declarations?.find(d => d.kind === SyntaxKind.PropertyDeclaration && !(d as PropertyDeclaration).initializer);
                             if (uninitialized
                                 && !(derived.flags & SymbolFlags.Transient)

diff --git a/src/compiler/transformers/es2015.ts b/src/compiler/transformers/es2015.ts
@@ -1626,7 +1626,7 @@ namespace ts {
             const memberFunction = transformFunctionLikeToExpression(member, /*location*/ member, /*name*/ undefined, container);
             const propertyName = visitNode(member.name, visitor, isPropertyName);
             let e: Expression;
-            if (!isPrivateIdentifier(propertyName) && context.getCompilerOptions().useDefineForClassFields) {
+            if (!isPrivateIdentifier(propertyName) && getUseDefineForClassFields(context.getCompilerOptions())) {
                 const name = isComputedPropertyName(propertyName) ? propertyName.expression
                     : isIdentifier(propertyName) ? factory.createStringLiteral(unescapeLeadingUnderscores(propertyName.escapedText))
                     : propertyName;

diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
@@ -6071,6 +6071,10 @@ namespace ts {
         return compilerOptions.allowJs === undefined ? !!compilerOptions.checkJs : compilerOptions.allowJs;
     }
 
+    export function getUseDefineForClassFields(compilerOptions: CompilerOptions): boolean {
+        return compilerOptions.useDefineForClassFields === undefined ? compilerOptions.target === ScriptTarget.ESNext : compilerOptions.useDefineForClassFields;
+    }
+
     export function compilerOptionsAffectSemanticDiagnostics(newOptions: CompilerOptions, oldOptions: CompilerOptions): boolean {
         return oldOptions !== newOptions &&
             semanticDiagnosticsOptionDeclarations.some(option => !isJsonEqual(getCompilerOptionValue(oldOptions, option), getCompilerOptionValue(newOptions, option)));

diff --git a/...s/conformance/classes/classExpressions/classWithStaticFieldInParameterBindingPattern.2.ts b/...s/conformance/classes/classExpressions/classWithStaticFieldInParameterBindingPattern.2.ts
@@ -1,6 +1,7 @@
 // @target: esnext,es2015,es5
 // @noTypesAndSymbols: true
 // @noEmit: true
+// @useDefineForClassFields: false
 
 // https://github.com/microsoft/TypeScript/issues/36295
 class C {}

diff --git a/...ases/conformance/classes/classExpressions/classWithStaticFieldInParameterInitializer.2.ts b/...ases/conformance/classes/classExpressions/classWithStaticFieldInParameterInitializer.2.ts
@@ -1,6 +1,7 @@
 // @target: esnext,es2015,es5
 // @noTypesAndSymbols: true
 // @noEmit: true
+// @useDefineForClassFields: false
 
 // https://github.com/microsoft/TypeScript/issues/36295
 class C {}