Emit extends clause for synthetic infer typesduring declaration emit

microsoft · Mar 24, 2022 · 2e4fa4f · 2e4fa4f
1 parent 0aded71
commit 2e4fa4f
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Showing 5 changed files with 102 additions and 4 deletions.
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -4977,7 +4977,20 @@ namespace ts {
                 if (type.flags & TypeFlags.TypeParameter || objectFlags & ObjectFlags.ClassOrInterface) {
                     if (type.flags & TypeFlags.TypeParameter && contains(context.inferTypeParameters, type)) {
                         context.approximateLength += (symbolName(type.symbol).length + 6);
-                        return factory.createInferTypeNode(typeParameterToDeclarationWithConstraint(type as TypeParameter, context, /*constraintNode*/ undefined));
+                        let constraintNode: TypeNode | undefined;
+                        const constraint = getConstraintOfTypeParameter(type as TypeParameter);
+                        if (constraint) {
+                            // If the infer type has a constraint that is not the same as the constraint
+                            // we would have normally inferred based on context, we emit the constraint
+                            // using `infer T extends ?`. We omit inferred constraints from type references
+                            // as they may be elided.
+                            const inferredConstraint = getInferredTypeParameterConstraint(type as TypeParameter, /*omitTypeReferences*/ true);
+                            if (!(inferredConstraint && isTypeIdenticalTo(constraint, inferredConstraint))) {
+                                context.approximateLength += 9;
+                                constraintNode = constraint && typeToTypeNodeHelper(constraint, context);
+                            }
+                        }
+                        return factory.createInferTypeNode(typeParameterToDeclarationWithConstraint(type as TypeParameter, context, constraintNode));
                     }
                     if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams &&
                         type.flags & TypeFlags.TypeParameter &&
@@ -13259,7 +13272,7 @@ namespace ts {
             return mapDefined(filter(type.symbol && type.symbol.declarations, isTypeParameterDeclaration), getEffectiveConstraintOfTypeParameter)[0];
         }
 
-        function getInferredTypeParameterConstraint(typeParameter: TypeParameter) {
+        function getInferredTypeParameterConstraint(typeParameter: TypeParameter, omitTypeReferences?: boolean) {
             let inferences: Type[] | undefined;
             if (typeParameter.symbol?.declarations) {
                 for (const declaration of typeParameter.symbol.declarations) {
@@ -13269,7 +13282,7 @@ namespace ts {
                         // corresponding type parameter in 'Foo'. When multiple 'infer T' declarations are
                         // present, we form an intersection of the inferred constraint types.
                         const [childTypeParameter = declaration.parent, grandParent] = walkUpParenthesizedTypesAndGetParentAndChild(declaration.parent.parent);
-                        if (grandParent.kind === SyntaxKind.TypeReference) {
+                        if (grandParent.kind === SyntaxKind.TypeReference && !omitTypeReferences) {
                             const typeReference = grandParent as TypeReferenceNode;
                             const typeParameters = getTypeParametersForTypeReference(typeReference);
                             if (typeParameters) {

diff --git a/tests/baselines/reference/inferTypesWithExtends1.js b/tests/baselines/reference/inferTypesWithExtends1.js
@@ -123,10 +123,26 @@ type X21_T5 = X21<1 | 2, 3>; // never
 
 // from mongoose
 type IfEquals<X, Y, A, B> = (<T>() => T extends X ? 1 : 2) extends <T>() => T extends Y ? 1 : 2 ? A : B;
-
+
+declare const x1: <T>() => (T extends infer U extends number ? 1 : 0);
+function f1() {
+    return x1;
+}
+
+type ExpectNumber<T extends number> = T;
+declare const x2: <T>() => (T extends ExpectNumber<infer U> ? 1 : 0);
+function f2() {
+    return x2;
+}
 
 //// [inferTypesWithExtends1.js]
 "use strict";
+function f1() {
+    return x1;
+}
+function f2() {
+    return x2;
+}
 
 
 //// [inferTypesWithExtends1.d.ts]
@@ -275,3 +291,8 @@ declare type X21_T3 = X21<1 | 2, 1>;
 declare type X21_T4 = X21<1 | 2, 2 | 3>;
 declare type X21_T5 = X21<1 | 2, 3>;
 declare type IfEquals<X, Y, A, B> = (<T>() => T extends X ? 1 : 2) extends <T>() => T extends Y ? 1 : 2 ? A : B;
+declare const x1: <T>() => (T extends infer U extends number ? 1 : 0);
+declare function f1(): <T>() => T extends infer U extends number ? 1 : 0;
+declare type ExpectNumber<T extends number> = T;
+declare const x2: <T>() => (T extends ExpectNumber<infer U> ? 1 : 0);
+declare function f2(): <T>() => T extends infer U extends number ? 1 : 0;
diff --git a/tests/baselines/reference/inferTypesWithExtends1.symbols b/tests/baselines/reference/inferTypesWithExtends1.symbols
@@ -498,3 +498,34 @@ type IfEquals<X, Y, A, B> = (<T>() => T extends X ? 1 : 2) extends <T>() => T ex
 >A : Symbol(A, Decl(inferTypesWithExtends1.ts, 123, 19))
 >B : Symbol(B, Decl(inferTypesWithExtends1.ts, 123, 22))
 
+declare const x1: <T>() => (T extends infer U extends number ? 1 : 0);
+>x1 : Symbol(x1, Decl(inferTypesWithExtends1.ts, 125, 13))
+>T : Symbol(T, Decl(inferTypesWithExtends1.ts, 125, 19))
+>T : Symbol(T, Decl(inferTypesWithExtends1.ts, 125, 19))
+>U : Symbol(U, Decl(inferTypesWithExtends1.ts, 125, 43))
+
+function f1() {
+>f1 : Symbol(f1, Decl(inferTypesWithExtends1.ts, 125, 70))
+
+    return x1;
+>x1 : Symbol(x1, Decl(inferTypesWithExtends1.ts, 125, 13))
+}
+
+type ExpectNumber<T extends number> = T;
+>ExpectNumber : Symbol(ExpectNumber, Decl(inferTypesWithExtends1.ts, 128, 1))
+>T : Symbol(T, Decl(inferTypesWithExtends1.ts, 130, 18))
+>T : Symbol(T, Decl(inferTypesWithExtends1.ts, 130, 18))
+
+declare const x2: <T>() => (T extends ExpectNumber<infer U> ? 1 : 0);
+>x2 : Symbol(x2, Decl(inferTypesWithExtends1.ts, 131, 13))
+>T : Symbol(T, Decl(inferTypesWithExtends1.ts, 131, 19))
+>T : Symbol(T, Decl(inferTypesWithExtends1.ts, 131, 19))
+>ExpectNumber : Symbol(ExpectNumber, Decl(inferTypesWithExtends1.ts, 128, 1))
+>U : Symbol(U, Decl(inferTypesWithExtends1.ts, 131, 56))
+
+function f2() {
+>f2 : Symbol(f2, Decl(inferTypesWithExtends1.ts, 131, 69))
+
+    return x2;
+>x2 : Symbol(x2, Decl(inferTypesWithExtends1.ts, 131, 13))
+}
diff --git a/tests/baselines/reference/inferTypesWithExtends1.types b/tests/baselines/reference/inferTypesWithExtends1.types
@@ -307,3 +307,25 @@ type X21_T5 = X21<1 | 2, 3>; // never
 type IfEquals<X, Y, A, B> = (<T>() => T extends X ? 1 : 2) extends <T>() => T extends Y ? 1 : 2 ? A : B;
 >IfEquals : IfEquals<X, Y, A, B>
 
+declare const x1: <T>() => (T extends infer U extends number ? 1 : 0);
+>x1 : <T>() => T extends infer U extends number ? 1 : 0
+
+function f1() {
+>f1 : () => <T>() => T extends infer U extends number ? 1 : 0
+
+    return x1;
+>x1 : <T>() => T extends infer U extends number ? 1 : 0
+}
+
+type ExpectNumber<T extends number> = T;
+>ExpectNumber : T
+
+declare const x2: <T>() => (T extends ExpectNumber<infer U> ? 1 : 0);
+>x2 : <T>() => T extends infer U extends number ? 1 : 0
+
+function f2() {
+>f2 : () => <T>() => T extends infer U extends number ? 1 : 0
+
+    return x2;
+>x2 : <T>() => T extends infer U extends number ? 1 : 0
+}
diff --git a/tests/cases/conformance/types/conditional/inferTypesWithExtends1.ts b/tests/cases/conformance/types/conditional/inferTypesWithExtends1.ts
@@ -125,3 +125,14 @@ type X21_T5 = X21<1 | 2, 3>; // never
 
 // from mongoose
 type IfEquals<X, Y, A, B> = (<T>() => T extends X ? 1 : 2) extends <T>() => T extends Y ? 1 : 2 ? A : B;
+
+declare const x1: <T>() => (T extends infer U extends number ? 1 : 0);
+function f1() {
+    return x1;
+}
+
+type ExpectNumber<T extends number> = T;
+declare const x2: <T>() => (T extends ExpectNumber<infer U> ? 1 : 0);
+function f2() {
+    return x2;
+}