Proposal class static block support (microsoft#43370)

* Class static block (microsoft#9)

* Add types factory and parser

* Add some case

* Make class static block as a container

* Update cases

* Add visitor

* Add emitter and more compile target

* Check boundary of break and continue

* Add basic transformer

* Fix emit behavior

* Add more tests

* Add friend tests

* Update baseline

* Fix cr issues

* Accept baseline

* Add decorator and modifier check

* Add functional boundary check

* Fix conflict

* Fix computed prop name within context

* Add more tests

* Update baseline

* Avoid invalid test baseline

* Support use before initialize check

* wip

* Fix class static block context

* Fix checks

* Fix missing case

* Improve assert message

* Accept baseline

* Avoid new context

* Update diagnostic message

* Fix name collision

* Fix targets

* Avoid unnecessary files

* Add more case

* Add more test cases

* Fix strict mode function declaration

* Avoid private fields initializer if no private identifier references

* Avoid private fields and add more test case

* Add more case

* Add tests and support for related services functionality

* Fix this reference in static block

* Split parser diagnostic and binder diagnostic

Co-authored-by: Ron Buckton <ron.buckton@microsoft.com>

Author: Kingwl

src/compiler/binder.ts

@@ -1832,6 +1832,7 @@ namespace ts {
                 case SyntaxKind.ConstructSignature:
                 case SyntaxKind.IndexSignature:
                 case SyntaxKind.ConstructorType:
+                case SyntaxKind.ClassStaticBlockDeclaration:
                     return ContainerFlags.IsContainer | ContainerFlags.IsControlFlowContainer | ContainerFlags.HasLocals | ContainerFlags.IsFunctionLike;
 
                 case SyntaxKind.FunctionExpression:
@@ -1867,7 +1868,7 @@ namespace ts {
                     // By not creating a new block-scoped-container here, we ensure that both 'var x'
                     // and 'let x' go into the Function-container's locals, and we do get a collision
                     // conflict.
-                    return isFunctionLike(node.parent) ? ContainerFlags.None : ContainerFlags.IsBlockScopedContainer;
+                    return isFunctionLike(node.parent) || isClassStaticBlockDeclaration(node.parent) ? ContainerFlags.None : ContainerFlags.IsBlockScopedContainer;
             }
 
             return ContainerFlags.None;
@@ -1929,6 +1930,7 @@ namespace ts {
                 case SyntaxKind.JSDocFunctionType:
                 case SyntaxKind.JSDocTypedefTag:
                 case SyntaxKind.JSDocCallbackTag:
+                case SyntaxKind.ClassStaticBlockDeclaration:
                 case SyntaxKind.TypeAliasDeclaration:
                 case SyntaxKind.MappedType:
                     // All the children of these container types are never visible through another
@@ -2328,7 +2330,7 @@ namespace ts {
                 // Report error if function is not top level function declaration
                 if (blockScopeContainer.kind !== SyntaxKind.SourceFile &&
                     blockScopeContainer.kind !== SyntaxKind.ModuleDeclaration &&
-                    !isFunctionLike(blockScopeContainer)) {
+                    !isFunctionLikeOrClassStaticBlockDeclaration(blockScopeContainer)) {
                     // We check first if the name is inside class declaration or class expression; if so give explicit message
                     // otherwise report generic error message.
                     const errorSpan = getErrorSpanForNode(file, node);
@@ -2712,7 +2714,7 @@ namespace ts {
                     updateStrictModeStatementList((node as SourceFile).statements);
                     return bindSourceFileIfExternalModule();
                 case SyntaxKind.Block:
-                    if (!isFunctionLike(node.parent)) {
+                    if (!isFunctionLikeOrClassStaticBlockDeclaration(node.parent)) {
                         return;
                     }
                     // falls through

src/compiler/checker.ts

@@ -24186,7 +24186,7 @@ namespace ts {
             // To avoid that we will give an error to users if they use arguments objects in arrow function so that they
             // can explicitly bound arguments objects
             if (symbol === argumentsSymbol) {
-                if (isInPropertyInitializer(node)) {
+                if (isInPropertyInitializerOrClassStaticBlock(node)) {
                     error(node, Diagnostics.arguments_cannot_be_referenced_in_property_initializers);
                     return errorType;
                 }
@@ -24544,6 +24544,9 @@ namespace ts {
                         // do not return here so in case if lexical this is captured - it will be reflected in flags on NodeLinks
                     }
                     break;
+                case SyntaxKind.ClassStaticBlockDeclaration:
+                    error(node, Diagnostics.this_cannot_be_referenced_in_current_location);
+                    break;
                 case SyntaxKind.ComputedPropertyName:
                     error(node, Diagnostics.this_cannot_be_referenced_in_a_computed_property_name);
                     break;
@@ -24602,7 +24605,8 @@ namespace ts {
 
             if (isClassLike(container.parent)) {
                 const symbol = getSymbolOfNode(container.parent);
-                const type = hasSyntacticModifier(container, ModifierFlags.Static) ? getTypeOfSymbol(symbol) : (getDeclaredTypeOfSymbol(symbol) as InterfaceType).thisType!;
+                const isStatic = hasSyntacticModifier(container, ModifierFlags.Static) || isClassStaticBlockDeclaration(container);
+                const type = isStatic ? getTypeOfSymbol(symbol) : (getDeclaredTypeOfSymbol(symbol) as InterfaceType).thisType!;
                 return getFlowTypeOfReference(node, type);
             }
 
@@ -27565,7 +27569,7 @@ namespace ts {
 
             let diagnosticMessage;
             const declarationName = idText(right);
-            if (isInPropertyInitializer(node)
+            if (isInPropertyInitializerOrClassStaticBlock(node)
                 && !isOptionalPropertyDeclaration(valueDeclaration)
                 && !(isAccessExpression(node) && isAccessExpression(node.expression))
                 && !isBlockScopedNameDeclaredBeforeUse(valueDeclaration, right)
@@ -27586,7 +27590,7 @@ namespace ts {
             }
         }
 
-        function isInPropertyInitializer(node: Node): boolean {
+        function isInPropertyInitializerOrClassStaticBlock(node: Node): boolean {
             return !!findAncestor(node, node => {
                 switch (node.kind) {
                     case SyntaxKind.PropertyDeclaration:
@@ -27606,6 +27610,8 @@ namespace ts {
                     case SyntaxKind.ExpressionWithTypeArguments:
                     case SyntaxKind.HeritageClause:
                         return false;
+                    case SyntaxKind.ExpressionStatement:
+                        return isBlock(node.parent) && isClassStaticBlockDeclaration(node.parent.parent) ? true : "quit";
                     default:
                         return isExpressionNode(node) ? false : "quit";
                 }
@@ -31303,7 +31309,11 @@ namespace ts {
         function checkAwaitExpression(node: AwaitExpression): Type {
             // Grammar checking
             if (produceDiagnostics) {
-                if (!(node.flags & NodeFlags.AwaitContext)) {
+                const container = getContainingFunctionOrClassStaticBlock(node);
+                if (container && isClassStaticBlockDeclaration(container)) {
+                    error(node, Diagnostics.Await_expression_cannot_be_used_inside_a_class_static_block);
+                }
+                else if (!(node.flags & NodeFlags.AwaitContext)) {
                     if (isInTopLevelContext(node)) {
                         const sourceFile = getSourceFileOfNode(node);
                         if (!hasParseDiagnostics(sourceFile)) {
@@ -31328,9 +31338,8 @@ namespace ts {
                         if (!hasParseDiagnostics(sourceFile)) {
                             const span = getSpanOfTokenAtPosition(sourceFile, node.pos);
                             const diagnostic = createFileDiagnostic(sourceFile, span.start, span.length, Diagnostics.await_expressions_are_only_allowed_within_async_functions_and_at_the_top_levels_of_modules);
-                            const func = getContainingFunction(node);
-                            if (func && func.kind !== SyntaxKind.Constructor && (getFunctionFlags(func) & FunctionFlags.Async) === 0) {
-                                const relatedInfo = createDiagnosticForNode(func, Diagnostics.Did_you_mean_to_mark_this_function_as_async);
+                            if (container && container.kind !== SyntaxKind.Constructor && (getFunctionFlags(container) & FunctionFlags.Async) === 0) {
+                                const relatedInfo = createDiagnosticForNode(container, Diagnostics.Did_you_mean_to_mark_this_function_as_async);
                                 addRelatedInfo(diagnostic, relatedInfo);
                             }
                             diagnostics.add(diagnostic);
@@ -33489,6 +33498,12 @@ namespace ts {
             }
         }
 
+        function checkClassStaticBlockDeclaration(node: ClassStaticBlockDeclaration) {
+            checkGrammarDecoratorsAndModifiers(node);
+
+            forEachChild(node, checkSourceElement);
+        }
+
         function checkConstructorDeclaration(node: ConstructorDeclaration) {
             // Grammar check on signature of constructor and modifier of the constructor is done in checkSignatureDeclaration function.
             checkSignatureDeclaration(node);
@@ -35096,10 +35111,11 @@ namespace ts {
                         break;
                     case SyntaxKind.IndexSignature:
                     case SyntaxKind.SemicolonClassElement:
+                    case SyntaxKind.ClassStaticBlockDeclaration:
                         // Can't be private
                         break;
                     default:
-                        Debug.fail();
+                        Debug.fail("Unexpected class member");
                 }
             }
         }
@@ -35531,6 +35547,7 @@ namespace ts {
             if (!node.name) {
                 return;
             }
+
             // For a computed property, just check the initializer and exit
             // Do not use hasDynamicName here, because that returns false for well known symbols.
             // We want to perform checkComputedPropertyName for all computed properties, including
@@ -35907,11 +35924,17 @@ namespace ts {
         function checkForOfStatement(node: ForOfStatement): void {
             checkGrammarForInOrForOfStatement(node);
 
+            const container = getContainingFunctionOrClassStaticBlock(node);
             if (node.awaitModifier) {
-                const functionFlags = getFunctionFlags(getContainingFunction(node));
-                if ((functionFlags & (FunctionFlags.Invalid | FunctionFlags.Async)) === FunctionFlags.Async && languageVersion < ScriptTarget.ESNext) {
-                    // for..await..of in an async function or async generator function prior to ESNext requires the __asyncValues helper
-                    checkExternalEmitHelpers(node, ExternalEmitHelpers.ForAwaitOfIncludes);
+                if (container && isClassStaticBlockDeclaration(container)) {
+                    grammarErrorOnNode(node.awaitModifier, Diagnostics.For_await_loops_cannot_be_used_inside_a_class_static_block);
+                }
+                else {
+                    const functionFlags = getFunctionFlags(container);
+                    if ((functionFlags & (FunctionFlags.Invalid | FunctionFlags.Async)) === FunctionFlags.Async && languageVersion < ScriptTarget.ESNext) {
+                        // for..await..of in an async function or async generator function prior to ESNext requires the __asyncValues helper
+                        checkExternalEmitHelpers(node, ExternalEmitHelpers.ForAwaitOfIncludes);
+                    }
                 }
             }
             else if (compilerOptions.downlevelIteration && languageVersion < ScriptTarget.ES2015) {
@@ -36791,28 +36814,33 @@ namespace ts {
                 return;
             }
 
-            const func = getContainingFunction(node);
-            if (!func) {
+            const container = getContainingFunctionOrClassStaticBlock(node);
+            if(container && isClassStaticBlockDeclaration(container)) {
+                grammarErrorOnFirstToken(node, Diagnostics.A_return_statement_cannot_be_used_inside_a_class_static_block);
+                return;
+            }
+
+            if (!container) {
                 grammarErrorOnFirstToken(node, Diagnostics.A_return_statement_can_only_be_used_within_a_function_body);
                 return;
             }
 
-            const signature = getSignatureFromDeclaration(func);
+            const signature = getSignatureFromDeclaration(container);
             const returnType = getReturnTypeOfSignature(signature);
-            const functionFlags = getFunctionFlags(func);
+            const functionFlags = getFunctionFlags(container);
             if (strictNullChecks || node.expression || returnType.flags & TypeFlags.Never) {
                 const exprType = node.expression ? checkExpressionCached(node.expression) : undefinedType;
-                if (func.kind === SyntaxKind.SetAccessor) {
+                if (container.kind === SyntaxKind.SetAccessor) {
                     if (node.expression) {
                         error(node, Diagnostics.Setters_cannot_return_a_value);
                     }
                 }
-                else if (func.kind === SyntaxKind.Constructor) {
+                else if (container.kind === SyntaxKind.Constructor) {
                     if (node.expression && !checkTypeAssignableToAndOptionallyElaborate(exprType, returnType, node, node.expression)) {
                         error(node, Diagnostics.Return_type_of_constructor_signature_must_be_assignable_to_the_instance_type_of_the_class);
                     }
                 }
-                else if (getReturnTypeFromAnnotation(func)) {
+                else if (getReturnTypeFromAnnotation(container)) {
                     const unwrappedReturnType = unwrapReturnType(returnType, functionFlags) ?? returnType;
                     const unwrappedExprType = functionFlags & FunctionFlags.Async
                         ? checkAwaitedType(exprType, node, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member)
@@ -36825,7 +36853,7 @@ namespace ts {
                     }
                 }
             }
-            else if (func.kind !== SyntaxKind.Constructor && compilerOptions.noImplicitReturns && !isUnwrappedReturnTypeVoidOrAny(func, returnType)) {
+            else if (container.kind !== SyntaxKind.Constructor && compilerOptions.noImplicitReturns && !isUnwrappedReturnTypeVoidOrAny(container, returnType)) {
                 // The function has a return type, but the return statement doesn't have an expression.
                 error(node, Diagnostics.Not_all_code_paths_return_a_value);
             }
@@ -38655,6 +38683,8 @@ namespace ts {
                 case SyntaxKind.MethodDeclaration:
                 case SyntaxKind.MethodSignature:
                     return checkMethodDeclaration(node as MethodDeclaration | MethodSignature);
+                case SyntaxKind.ClassStaticBlockDeclaration:
+                    return checkClassStaticBlockDeclaration(node as ClassStaticBlockDeclaration);
                 case SyntaxKind.Constructor:
                     return checkConstructorDeclaration(node as ConstructorDeclaration);
                 case SyntaxKind.GetAccessor:
@@ -41132,6 +41162,7 @@ namespace ts {
                         case SyntaxKind.InterfaceDeclaration:
                         case SyntaxKind.VariableStatement:
                         case SyntaxKind.TypeAliasDeclaration:
+                        case SyntaxKind.ClassStaticBlockDeclaration:
                             return true;
                         case SyntaxKind.EnumDeclaration:
                             return nodeHasAnyModifiersExcept(node, SyntaxKind.ConstKeyword);
@@ -41869,7 +41900,7 @@ namespace ts {
         function checkGrammarBreakOrContinueStatement(node: BreakOrContinueStatement): boolean {
             let current: Node = node;
             while (current) {
-                if (isFunctionLike(current)) {
+                if (isFunctionLikeOrClassStaticBlockDeclaration(current)) {
                     return grammarErrorOnNode(node, Diagnostics.Jump_target_cannot_cross_function_boundary);
                 }
 

src/compiler/diagnosticMessages.json

@@ -7154,5 +7154,21 @@
     "Class decorators can't be used with static private identifier. Consider removing the experimental decorator.": {
         "category": "Error",
         "code": 18036
+    },
+    "Await expression cannot be used inside a class static block.": {
+        "category": "Error",
+        "code": 18037
+    },
+    "'For await' loops cannot be used inside a class static block.": {
+        "category": "Error",
+        "code": 18038
+    },
+    "Invalid use of '{0}'. It cannot be used inside a class static block.": {
+        "category": "Error",
+        "code": 18039
+    },
+    "A 'return' statement cannot be used inside a class static block.": {
+        "category": "Error",
+        "code": 18041
     }
 }

src/compiler/emitter.ts

@@ -1351,6 +1351,8 @@ namespace ts {
                         return emitMethodSignature(node as MethodSignature);
                     case SyntaxKind.MethodDeclaration:
                         return emitMethodDeclaration(node as MethodDeclaration);
+                    case SyntaxKind.ClassStaticBlockDeclaration:
+                        return emitClassStaticBlockDeclaration(node as ClassStaticBlockDeclaration);
                     case SyntaxKind.Constructor:
                         return emitConstructor(node as ConstructorDeclaration);
                     case SyntaxKind.GetAccessor:
@@ -2063,6 +2065,13 @@ namespace ts {
             emitSignatureAndBody(node, emitSignatureHead);
         }
 
+        function emitClassStaticBlockDeclaration(node: ClassStaticBlockDeclaration) {
+            emitDecorators(node, node.decorators);
+            emitModifiers(node, node.modifiers);
+            writeKeyword("static");
+            emitBlockFunctionBody(node.body);
+        }
+
         function emitConstructor(node: ConstructorDeclaration) {
             emitModifiers(node, node.modifiers);
             writeKeyword("constructor");

src/compiler/factory/nodeFactory.ts

@@ -94,6 +94,8 @@ namespace ts {
             updateConstructSignature,
             createIndexSignature,
             updateIndexSignature,
+            createClassStaticBlockDeclaration,
+            updateClassStaticBlockDeclaration,
             createTemplateLiteralTypeSpan,
             updateTemplateLiteralTypeSpan,
             createKeywordTypeNode,
@@ -1415,6 +1417,38 @@ namespace ts {
                 : node;
         }
 
+        // @api
+        function createClassStaticBlockDeclaration(
+            decorators: readonly Decorator[] | undefined,
+            modifiers: readonly Modifier[] | undefined,
+            body: Block
+        ): ClassStaticBlockDeclaration {
+            const node = createBaseGenericNamedDeclaration<ClassStaticBlockDeclaration>(
+                SyntaxKind.ClassStaticBlockDeclaration,
+                decorators,
+                modifiers,
+                /*name*/ undefined,
+                /*typeParameters*/ undefined
+            );
+            node.body = body;
+            node.transformFlags = propagateChildFlags(body) | TransformFlags.ContainsClassFields;
+            return node;
+        }
+
+        // @api
+        function updateClassStaticBlockDeclaration(
+            node: ClassStaticBlockDeclaration,
+            decorators: readonly Decorator[] | undefined,
+            modifiers: readonly Modifier[] | undefined,
+            body: Block
+        ): ClassStaticBlockDeclaration {
+            return node.decorators !== decorators
+                || node.modifier !== modifiers
+                || node.body !== body
+                ? update(createClassStaticBlockDeclaration(decorators, modifiers, body), node)
+                : node;
+        }
+
         // @api
         function createConstructorDeclaration(
             decorators: readonly Decorator[] | undefined,

src/compiler/factory/nodeTests.ts

@@ -182,6 +182,10 @@ namespace ts {
         return node.kind === SyntaxKind.MethodDeclaration;
     }
 
+    export function isClassStaticBlockDeclaration(node: Node): node is ClassStaticBlockDeclaration {
+        return node.kind === SyntaxKind.ClassStaticBlockDeclaration;
+    }
+
     export function isConstructorDeclaration(node: Node): node is ConstructorDeclaration {
         return node.kind === SyntaxKind.Constructor;
     }