Ensure TypeChecker#getTypeAtLocation returns a defined result

src/compiler/checker.ts

@@ -18834,7 +18834,7 @@ namespace ts {
                 node.kind === SyntaxKind.SetAccessor) {
                 // The `descriptor` for a method decorator will be a `TypedPropertyDescriptor<T>`
                 // for the type of the member.
-                const propertyType = getTypeOfNode(node)!; // TODO: GH#18217
+                const propertyType = getTypeOfNode(node);
                 return createTypedPropertyDescriptorType(propertyType);
             }
 
@@ -21849,7 +21849,7 @@ namespace ts {
                     else {
                         const leadingError = () => chainDiagnosticMessages(/*details*/ undefined, Diagnostics.A_type_predicate_s_type_must_be_assignable_to_its_parameter_s_type);
                         checkTypeAssignableTo(typePredicate.type,
-                            getTypeOfNode(parent.parameters[typePredicate.parameterIndex])!, // TODO: GH#18217
+                            getTypeOfNode(parent.parameters[typePredicate.parameterIndex]),
                             node.type,
                             /*headMessage*/ undefined,
                             leadingError);
@@ -23181,7 +23181,7 @@ namespace ts {
                 case SyntaxKind.MethodDeclaration:
                 case SyntaxKind.GetAccessor:
                 case SyntaxKind.SetAccessor:
-                    const methodType = getTypeOfNode(node.parent)!; // TODO: GH#18217
+                    const methodType = getTypeOfNode(node.parent);
                     const descriptorType = createTypedPropertyDescriptorType(methodType);
                     expectedReturnType = getUnionType([descriptorType, voidType]);
                     break;
@@ -27120,7 +27120,7 @@ namespace ts {
                 resolveEntityName(node.propertyName || node.name, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias);
         }
 
-        function getTypeOfNode(node: Node): Type | undefined {
+        function getTypeOfNode(node: Node): Type {
             if (node.flags & NodeFlags.InWithStatement) {
                 // We cannot answer semantic questions within a with block, do not proceed any further
                 return errorType;
@@ -27159,7 +27159,7 @@ namespace ts {
 
             if (isTypeDeclarationName(node)) {
                 const symbol = getSymbolAtLocation(node);
-                return symbol && getDeclaredTypeOfSymbol(symbol);
+                return symbol ? getDeclaredTypeOfSymbol(symbol) : errorType;
             }
 
             if (isDeclaration(node)) {
@@ -27170,11 +27170,11 @@ namespace ts {
 
             if (isDeclarationNameOrImportPropertyName(node)) {
                 const symbol = getSymbolAtLocation(node);
-                return symbol && getTypeOfSymbol(symbol);
+                return symbol ? getTypeOfSymbol(symbol) : errorType;
             }
 
             if (isBindingPattern(node)) {
-                return getTypeForVariableLikeDeclaration(node.parent, /*includeOptionality*/ true);
+                return getTypeForVariableLikeDeclaration(node.parent, /*includeOptionality*/ true) || errorType;
             }
 
             if (isInRightSideOfImportOrExportAssignment(<Identifier>node)) {

src/compiler/types.ts

@@ -2936,7 +2936,7 @@ namespace ts {
          */
         getExportSymbolOfSymbol(symbol: Symbol): Symbol;
         getPropertySymbolOfDestructuringAssignment(location: Identifier): Symbol | undefined;
-        getTypeAtLocation(node: Node): Type | undefined;
+        getTypeAtLocation(node: Node): Type;
         getTypeFromTypeNode(node: TypeNode): Type;
 
         signatureToString(signature: Signature, enclosingDeclaration?: Node, flags?: TypeFormatFlags, kind?: SignatureKind): string;

src/services/codefixes/fixAddMissingMember.ts

@@ -124,7 +124,7 @@ namespace ts.codefix {
         const { parent } = token;
         if (!isPropertyAccessExpression(parent)) return undefined;
 
-        const leftExpressionType = skipConstraint(checker.getTypeAtLocation(parent.expression)!);
+        const leftExpressionType = skipConstraint(checker.getTypeAtLocation(parent.expression));
         const { symbol } = leftExpressionType;
         if (!symbol || !symbol.declarations) return undefined;
 
@@ -183,7 +183,7 @@ namespace ts.codefix {
         if (token.parent.parent.kind === SyntaxKind.BinaryExpression) {
             const binaryExpression = token.parent.parent as BinaryExpression;
             const otherExpression = token.parent === binaryExpression.left ? binaryExpression.right : binaryExpression.left;
-            const widenedType = checker.getWidenedType(checker.getBaseTypeOfLiteralType(checker.getTypeAtLocation(otherExpression)!)); // TODO: GH#18217
+            const widenedType = checker.getWidenedType(checker.getBaseTypeOfLiteralType(checker.getTypeAtLocation(otherExpression)));
             typeNode = checker.typeToTypeNode(widenedType, classDeclaration);
         }
         return typeNode || createKeywordTypeNode(SyntaxKind.AnyKeyword);

src/services/codefixes/fixClassDoesntImplementInheritedAbstractMember.ts

@@ -34,7 +34,7 @@ namespace ts.codefix {
 
     function addMissingMembers(classDeclaration: ClassLikeDeclaration, sourceFile: SourceFile, checker: TypeChecker, changeTracker: textChanges.ChangeTracker, preferences: UserPreferences): void {
         const extendsNode = getEffectiveBaseTypeNode(classDeclaration)!;
-        const instantiatedExtendsType = checker.getTypeAtLocation(extendsNode)!;
+        const instantiatedExtendsType = checker.getTypeAtLocation(extendsNode);
 
         // Note that this is ultimately derived from a map indexed by symbol names,
         // so duplicates cannot occur.

src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts

@@ -51,7 +51,7 @@ namespace ts.codefix {
         const implementedTypeSymbols = checker.getPropertiesOfType(implementedType);
         const nonPrivateAndNotExistedInHeritageClauseMembers = implementedTypeSymbols.filter(and(symbolPointsToNonPrivateMember, symbol => !maybeHeritageClauseSymbol.has(symbol.escapedName)));
 
-        const classType = checker.getTypeAtLocation(classDeclaration)!;
+        const classType = checker.getTypeAtLocation(classDeclaration);
 
         if (!classType.getNumberIndexType()) {
             createMissingIndexSignatureDeclaration(implementedType, IndexKind.Number);

src/services/codefixes/fixInvalidImportSyntax.ts

@@ -77,7 +77,7 @@ namespace ts.codefix {
     }
 
     function getImportCodeFixesForExpression(context: CodeFixContext, expr: Node): CodeFixAction[] | undefined {
-        const type = context.program.getTypeChecker().getTypeAtLocation(expr)!; // TODO: GH#18217
+        const type = context.program.getTypeChecker().getTypeAtLocation(expr);
         if (!(type.symbol && (type.symbol as TransientSymbol).originatingImport)) {
             return [];
         }

src/services/codefixes/fixSpelling.ts

@@ -35,7 +35,7 @@ namespace ts.codefix {
         let suggestion: string | undefined;
         if (isPropertyAccessExpression(node.parent) && node.parent.name === node) {
             Debug.assert(node.kind === SyntaxKind.Identifier);
-            const containingType = checker.getTypeAtLocation(node.parent.expression)!;
+            const containingType = checker.getTypeAtLocation(node.parent.expression);
             suggestion = checker.getSuggestionForNonexistentProperty(node as Identifier, containingType);
         }
         else if (isImportSpecifier(node.parent) && node.parent.name === node) {

src/services/codefixes/inferFromUsage.ts

@@ -401,7 +401,7 @@ namespace ts.codefix {
                 case SyntaxKind.LessThanEqualsToken:
                 case SyntaxKind.GreaterThanToken:
                 case SyntaxKind.GreaterThanEqualsToken:
-                    const operandType = checker.getTypeAtLocation(parent.left === node ? parent.right : parent.left)!;
+                    const operandType = checker.getTypeAtLocation(parent.left === node ? parent.right : parent.left);
                     if (operandType.flags & TypeFlags.EnumLike) {
                         addCandidateType(usageContext, operandType);
                     }
@@ -412,7 +412,7 @@ namespace ts.codefix {
 
                 case SyntaxKind.PlusEqualsToken:
                 case SyntaxKind.PlusToken:
-                    const otherOperandType = checker.getTypeAtLocation(parent.left === node ? parent.right : parent.left)!;
+                    const otherOperandType = checker.getTypeAtLocation(parent.left === node ? parent.right : parent.left);
                     if (otherOperandType.flags & TypeFlags.EnumLike) {
                         addCandidateType(usageContext, otherOperandType);
                     }
@@ -472,7 +472,7 @@ namespace ts.codefix {
 
             if (parent.arguments) {
                 for (const argument of parent.arguments) {
-                    callContext.argumentTypes.push(checker.getTypeAtLocation(argument)!);
+                    callContext.argumentTypes.push(checker.getTypeAtLocation(argument));
                 }
             }
 
@@ -501,7 +501,7 @@ namespace ts.codefix {
                 return;
             }
             else {
-                const indexType = checker.getTypeAtLocation(parent)!;
+                const indexType = checker.getTypeAtLocation(parent);
                 const indexUsageContext = {};
                 inferTypeFromContext(parent, checker, indexUsageContext);
                 if (indexType.flags & TypeFlags.NumberLike) {

src/services/completions.ts

@@ -1098,7 +1098,7 @@ namespace ts.Completions {
             }
 
             if (!isTypeLocation) {
-                addTypeProperties(typeChecker.getTypeAtLocation(node)!);
+                addTypeProperties(typeChecker.getTypeAtLocation(node));
             }
         }
 

src/services/goToDefinition.ts

@@ -171,7 +171,7 @@ namespace ts.GoToDefinition {
     // At 'x.foo', see if the type of 'x' has an index signature, and if so find its declarations.
     function getDefinitionInfoForIndexSignatures(node: Node, checker: TypeChecker): DefinitionInfo[] | undefined {
         if (!isPropertyAccessExpression(node.parent) || node.parent.name !== node) return;
-        const type = checker.getTypeAtLocation(node.parent.expression)!;
+        const type = checker.getTypeAtLocation(node.parent.expression);
         return mapDefined(type.isUnionOrIntersection() ? type.types : [type], nonUnionType => {
             const info = checker.getIndexInfoOfType(nonUnionType, IndexKind.String);
             return info && info.declaration && createDefinitionFromSignatureDeclaration(checker, info.declaration);

src/services/refactors/extractSymbol.ts

@@ -866,7 +866,7 @@ namespace ts.refactor.extractSymbol {
 
                     // Being returned through an object literal will have widened the type.
                     const variableType: TypeNode | undefined = checker.typeToTypeNode(
-                        checker.getBaseTypeOfLiteralType(checker.getTypeAtLocation(variableDeclaration)!), // TODO: GH#18217
+                        checker.getBaseTypeOfLiteralType(checker.getTypeAtLocation(variableDeclaration)),
                         scope,
                         NodeBuilderFlags.NoTruncation);
 
@@ -1406,7 +1406,7 @@ namespace ts.refactor.extractSymbol {
             const end = last(statements).end;
             expressionDiagnostic = createFileDiagnostic(sourceFile, start, end - start, Messages.expressionExpected);
         }
-        else if (checker.getTypeAtLocation(expression)!.flags & (TypeFlags.Void | TypeFlags.Never)) { // TODO: GH#18217
+        else if (checker.getTypeAtLocation(expression).flags & (TypeFlags.Void | TypeFlags.Never)) {
             expressionDiagnostic = createDiagnosticForNode(expression, Messages.uselessConstantType);
         }
 
@@ -1555,7 +1555,7 @@ namespace ts.refactor.extractSymbol {
 
         function collectUsages(node: Node, valueUsage = Usage.Read) {
             if (inGenericContext) {
-                const type = checker.getTypeAtLocation(node)!; // TODO: GH#18217
+                const type = checker.getTypeAtLocation(node);
                 recordTypeParameterUsages(type);
             }
 

src/services/symbolDisplay.ts

@@ -172,7 +172,7 @@ namespace ts.SymbolDisplay {
 
                 const useConstructSignatures = callExpressionLike.kind === SyntaxKind.NewExpression || (isCallExpression(callExpressionLike) && callExpressionLike.expression.kind === SyntaxKind.SuperKeyword);
 
-                const allSignatures = useConstructSignatures ? type!.getConstructSignatures() : type!.getCallSignatures();
+                const allSignatures = useConstructSignatures ? type.getConstructSignatures() : type.getCallSignatures();
 
                 if (!contains(allSignatures, signature.target) && !contains(allSignatures, signature)) {
                     // Get the first signature if there is one -- allSignatures may contain
@@ -184,7 +184,7 @@ namespace ts.SymbolDisplay {
                     if (useConstructSignatures && (symbolFlags & SymbolFlags.Class)) {
                         // Constructor
                         symbolKind = ScriptElementKind.constructorImplementationElement;
-                        addPrefixForAnyFunctionOrVar(type!.symbol, symbolKind);
+                        addPrefixForAnyFunctionOrVar(type.symbol, symbolKind);
                     }
                     else if (symbolFlags & SymbolFlags.Alias) {
                         symbolKind = ScriptElementKind.alias;
@@ -211,8 +211,8 @@ namespace ts.SymbolDisplay {
                             // If it is call or construct signature of lambda's write type name
                             displayParts.push(punctuationPart(SyntaxKind.ColonToken));
                             displayParts.push(spacePart());
-                            if (!(getObjectFlags(type!) & ObjectFlags.Anonymous) && type!.symbol) {
-                                addRange(displayParts, symbolToDisplayParts(typeChecker, type!.symbol, enclosingDeclaration, /*meaning*/ undefined, SymbolFormatFlags.AllowAnyNodeKind | SymbolFormatFlags.WriteTypeParametersOrArguments));
+                            if (!(getObjectFlags(type) & ObjectFlags.Anonymous) && type.symbol) {
+                                addRange(displayParts, symbolToDisplayParts(typeChecker, type.symbol, enclosingDeclaration, /*meaning*/ undefined, SymbolFormatFlags.AllowAnyNodeKind | SymbolFormatFlags.WriteTypeParametersOrArguments));
                                 displayParts.push(lineBreakPart());
                             }
                             if (useConstructSignatures) {
@@ -238,7 +238,7 @@ namespace ts.SymbolDisplay {
                     declaration === (location.kind === SyntaxKind.ConstructorKeyword ? functionDeclaration.parent : functionDeclaration));
 
                 if (locationIsSymbolDeclaration) {
-                    const allSignatures = functionDeclaration.kind === SyntaxKind.Constructor ? type!.getNonNullableType().getConstructSignatures() : type!.getNonNullableType().getCallSignatures();
+                    const allSignatures = functionDeclaration.kind === SyntaxKind.Constructor ? type.getNonNullableType().getConstructSignatures() : type.getNonNullableType().getCallSignatures();
                     if (!typeChecker.isImplementationOfOverload(functionDeclaration)) {
                         signature = typeChecker.getSignatureFromDeclaration(functionDeclaration)!; // TODO: GH#18217
                     }
@@ -249,12 +249,12 @@ namespace ts.SymbolDisplay {
                     if (functionDeclaration.kind === SyntaxKind.Constructor) {
                         // show (constructor) Type(...) signature
                         symbolKind = ScriptElementKind.constructorImplementationElement;
-                        addPrefixForAnyFunctionOrVar(type!.symbol, symbolKind);
+                        addPrefixForAnyFunctionOrVar(type.symbol, symbolKind);
                     }
                     else {
                         // (function/method) symbol(..signature)
                         addPrefixForAnyFunctionOrVar(functionDeclaration.kind === SyntaxKind.CallSignature &&
-                            !(type!.symbol.flags & SymbolFlags.TypeLiteral || type!.symbol.flags & SymbolFlags.ObjectLiteral) ? type!.symbol : symbol, symbolKind);
+                            !(type.symbol.flags & SymbolFlags.TypeLiteral || type.symbol.flags & SymbolFlags.ObjectLiteral) ? type.symbol : symbol, symbolKind);
                     }
 
                     addSignatureDisplayParts(signature, allSignatures);

src/services/utilities.ts

@@ -925,7 +925,7 @@ namespace ts {
     }
 
     export function getPossibleGenericSignatures(called: Expression, typeArgumentCount: number, checker: TypeChecker): ReadonlyArray<Signature> {
-        const type = checker.getTypeAtLocation(called)!; // TODO: GH#18217
+        const type = checker.getTypeAtLocation(called);
         const signatures = isNewExpression(called.parent) ? type.getConstructSignatures() : type.getCallSignatures();
         return signatures.filter(candidate => !!candidate.typeParameters && candidate.typeParameters.length >= typeArgumentCount);
     }

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -1901,7 +1901,7 @@ declare namespace ts {
          */
         getExportSymbolOfSymbol(symbol: Symbol): Symbol;
         getPropertySymbolOfDestructuringAssignment(location: Identifier): Symbol | undefined;
-        getTypeAtLocation(node: Node): Type | undefined;
+        getTypeAtLocation(node: Node): Type;
         getTypeFromTypeNode(node: TypeNode): Type;
         signatureToString(signature: Signature, enclosingDeclaration?: Node, flags?: TypeFormatFlags, kind?: SignatureKind): string;
         typeToString(type: Type, enclosingDeclaration?: Node, flags?: TypeFormatFlags): string;

tests/baselines/reference/api/typescript.d.ts

@@ -1901,7 +1901,7 @@ declare namespace ts {
          */
         getExportSymbolOfSymbol(symbol: Symbol): Symbol;
         getPropertySymbolOfDestructuringAssignment(location: Identifier): Symbol | undefined;
-        getTypeAtLocation(node: Node): Type | undefined;
+        getTypeAtLocation(node: Node): Type;
         getTypeFromTypeNode(node: TypeNode): Type;
         signatureToString(signature: Signature, enclosingDeclaration?: Node, flags?: TypeFormatFlags, kind?: SignatureKind): string;
         typeToString(type: Type, enclosingDeclaration?: Node, flags?: TypeFormatFlags): string;

tests/baselines/reference/umd-errors.types

@@ -1,15 +1,15 @@
 === tests/cases/conformance/externalModules/err1.d.ts ===
 // Illegal, can't be in script file
 export as namespace Foo;
->Foo : No type information available!
+>Foo : any
 
 === tests/cases/conformance/externalModules/err2.d.ts ===
 // Illegal, can't be in external ambient module
 declare module "Foo" {
 >"Foo" : typeof import("Foo")
 
 	export as namespace Bar;
->Bar : No type information available!
+>Bar : any
 }
 
 === tests/cases/conformance/externalModules/err3.d.ts ===
@@ -35,7 +35,7 @@ export namespace B {
 >B : typeof B
 
 	export as namespace C1;
->C1 : No type information available!
+>C1 : any
 }
 
 === tests/cases/conformance/externalModules/err5.ts ===
@@ -44,6 +44,6 @@ export var v;
 >v : any
 
 export as namespace C2;
->C2 : No type information available!
+>C2 : any