Support contextual type discrimination based on template literal expressions

src/compiler/checker.ts

@@ -2065,6 +2065,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
     var autoType = createIntrinsicType(TypeFlags.Any, "any", ObjectFlags.NonInferrableType, "auto");
     var wildcardType = createIntrinsicType(TypeFlags.Any, "any", /*objectFlags*/ undefined, "wildcard");
     var blockedStringType = createIntrinsicType(TypeFlags.Any, "any", /*objectFlags*/ undefined, "blocked string");
+    var contextFreeType = createIntrinsicType(TypeFlags.Any, "any", /*objectFlags*/ undefined, "context free");
     var errorType = createIntrinsicType(TypeFlags.Any, "error");
     var unresolvedType = createIntrinsicType(TypeFlags.Any, "unresolved");
     var nonInferrableAnyType = createIntrinsicType(TypeFlags.Any, "any", ObjectFlags.ContainsWideningType, "non-inferrable");
@@ -41198,10 +41199,14 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             types.push(isTypeAssignableTo(type, templateConstraintType) ? type : stringType);
         }
         const evaluated = node.parent.kind !== SyntaxKind.TaggedTemplateExpression && evaluate(node).value;
-        if (evaluated) {
+        if (typeof evaluated === "string") {
             return getFreshTypeOfLiteralType(getStringLiteralType(evaluated));
         }
-        if (isConstContext(node) || isTemplateLiteralContext(node) || someType(getContextualType(node, /*contextFlags*/ undefined) || unknownType, isTemplateLiteralContextualType)) {
+        if (isConstContext(node) || isTemplateLiteralContext(node)) {
+            return getTemplateLiteralType(texts, types);
+        }
+        const contextualType = getContextualType(node, /*contextFlags*/ undefined) || unknownType;
+        if (contextualType === contextFreeType ? every(types, t => isLiteralType(t) || isPatternLiteralPlaceholderType(t)) : someType(contextualType, isTemplateLiteralContextualType)) {
             return getTemplateLiteralType(texts, types);
         }
         return stringType;
@@ -41651,7 +41656,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         if (links.contextFreeType) {
             return links.contextFreeType;
         }
-        pushContextualType(node, anyType, /*isCache*/ false);
+        pushContextualType(node, contextFreeType, /*isCache*/ false);
         const type = links.contextFreeType = checkExpression(node, CheckMode.SkipContextSensitive);
         popContextualType();
         return type;

tests/baselines/reference/discriminantUsingEvaluatableTemplateExpression.symbols

@@ -37,3 +37,35 @@ foo({
   },
 });
 
+type E1 = { d: "main1-sub1"; cb: (x: string) => void };
+>E1 : Symbol(E1, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 12, 3))
+>d : Symbol(d, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 14, 11))
+>cb : Symbol(cb, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 14, 28))
+>x : Symbol(x, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 14, 34))
+
+type E2 = { d: "main2-sub2"; cb: (x: number) => void };
+>E2 : Symbol(E2, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 14, 55))
+>d : Symbol(d, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 15, 11))
+>cb : Symbol(cb, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 15, 28))
+>x : Symbol(x, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 15, 34))
+
+declare function bar(_: E1 | E2): void;
+>bar : Symbol(bar, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 15, 55))
+>_ : Symbol(_, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 17, 21))
+>E1 : Symbol(E1, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 12, 3))
+>E2 : Symbol(E2, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 14, 55))
+
+const someCategory = "main1";
+>someCategory : Symbol(someCategory, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 19, 5))
+
+const someSubcategory = "sub1";
+>someSubcategory : Symbol(someSubcategory, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 20, 5))
+
+bar({ d: `${someCategory}-${someSubcategory}`, cb: (x) => {} });
+>bar : Symbol(bar, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 15, 55))
+>d : Symbol(d, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 22, 5))
+>someCategory : Symbol(someCategory, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 19, 5))
+>someSubcategory : Symbol(someSubcategory, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 20, 5))
+>cb : Symbol(cb, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 22, 46))
+>x : Symbol(x, Decl(discriminantUsingEvaluatableTemplateExpression.ts, 22, 52))
+

tests/baselines/reference/discriminantUsingEvaluatableTemplateExpression.types

@@ -60,3 +60,63 @@ foo({
   },
 });
 
+type E1 = { d: "main1-sub1"; cb: (x: string) => void };
+>E1 : E1
+>   : ^^
+>d : "main1-sub1"
+>  : ^^^^^^^^^^^^
+>cb : (x: string) => void
+>   : ^ ^^      ^^^^^    
+>x : string
+>  : ^^^^^^
+
+type E2 = { d: "main2-sub2"; cb: (x: number) => void };
+>E2 : E2
+>   : ^^
+>d : "main2-sub2"
+>  : ^^^^^^^^^^^^
+>cb : (x: number) => void
+>   : ^ ^^      ^^^^^    
+>x : number
+>  : ^^^^^^
+
+declare function bar(_: E1 | E2): void;
+>bar : (_: E1 | E2) => void
+>    : ^ ^^       ^^^^^    
+>_ : E1 | E2
+>  : ^^^^^^^
+
+const someCategory = "main1";
+>someCategory : "main1"
+>             : ^^^^^^^
+>"main1" : "main1"
+>        : ^^^^^^^
+
+const someSubcategory = "sub1";
+>someSubcategory : "sub1"
+>                : ^^^^^^
+>"sub1" : "sub1"
+>       : ^^^^^^
+
+bar({ d: `${someCategory}-${someSubcategory}`, cb: (x) => {} });
+>bar({ d: `${someCategory}-${someSubcategory}`, cb: (x) => {} }) : void
+>                                                                : ^^^^
+>bar : (_: E1 | E2) => void
+>    : ^ ^^       ^^^^^    
+>{ d: `${someCategory}-${someSubcategory}`, cb: (x) => {} } : { d: "main1-sub1"; cb: (x: string) => void; }
+>                                                           : ^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^
+>d : "main1-sub1"
+>  : ^^^^^^^^^^^^
+>`${someCategory}-${someSubcategory}` : "main1-sub1"
+>                                     : ^^^^^^^^^^^^
+>someCategory : "main1"
+>             : ^^^^^^^
+>someSubcategory : "sub1"
+>                : ^^^^^^
+>cb : (x: string) => void
+>   : ^ ^^^^^^^^^^^^^^^^^
+>(x) => {} : (x: string) => void
+>          : ^ ^^^^^^^^^^^^^^^^^
+>x : string
+>  : ^^^^^^
+

tests/baselines/reference/discriminatedUnionTypesOverlappingDiscriminants1.errors.txt

@@ -0,0 +1,196 @@
+discriminatedUnionTypesOverlappingDiscriminants1.ts(83,7): error TS2322: Type '{ audience: "earth"; meal: "vegetable_cow"; }' is not assignable to type 'Target'.
+  Types of property 'meal' are incompatible.
+    Type '"vegetable_cow"' is not assignable to type 'Custom | "fruit_apple" | "fruit_orange" | "vegetable_spinach" | "vegetable_carrot" | "other_milk" | "other_water"'. Did you mean '"vegetable_carrot"'?
+discriminatedUnionTypesOverlappingDiscriminants1.ts(89,7): error TS2322: Type '{ meal: string; audience: "earth"; }' is not assignable to type 'Target'.
+  Types of property 'audience' are incompatible.
+    Type '"earth"' is not assignable to type '"mars" | "jupiter"'.
+discriminatedUnionTypesOverlappingDiscriminants1.ts(97,7): error TS2322: Type '{ audience: "earth"; meal: "vegetable_cow"; }' is not assignable to type 'Target'.
+  Types of property 'meal' are incompatible.
+    Type '"vegetable_cow"' is not assignable to type 'Custom | "fruit_apple" | "fruit_orange" | "vegetable_spinach" | "vegetable_carrot" | "other_milk" | "other_water"'. Did you mean '"vegetable_carrot"'?
+discriminatedUnionTypesOverlappingDiscriminants1.ts(103,7): error TS2322: Type '{ meal: string; audience: "earth"; }' is not assignable to type 'Target'.
+  Types of property 'audience' are incompatible.
+    Type '"earth"' is not assignable to type '"mars" | "jupiter"'.
+discriminatedUnionTypesOverlappingDiscriminants1.ts(111,7): error TS2322: Type '{ audience: "earth"; meal: "vegetable_cow"; }' is not assignable to type 'Target'.
+  Types of property 'meal' are incompatible.
+    Type '"vegetable_cow"' is not assignable to type 'Custom | "fruit_apple" | "fruit_orange" | "vegetable_spinach" | "vegetable_carrot" | "other_milk" | "other_water"'. Did you mean '"vegetable_carrot"'?
+discriminatedUnionTypesOverlappingDiscriminants1.ts(117,7): error TS2322: Type '{ meal: string; audience: "earth"; }' is not assignable to type 'Target'.
+  Types of property 'audience' are incompatible.
+    Type '"earth"' is not assignable to type '"mars" | "jupiter"'.
+discriminatedUnionTypesOverlappingDiscriminants1.ts(125,7): error TS2322: Type '{ audience: "earth"; meal: "vegetable_cow" | "vegetable_pig"; }' is not assignable to type 'Target'.
+  Types of property 'meal' are incompatible.
+    Type '"vegetable_cow" | "vegetable_pig"' is not assignable to type 'Custom | "fruit_apple" | "fruit_orange" | "vegetable_spinach" | "vegetable_carrot" | "other_milk" | "other_water"'.
+      Type '"vegetable_cow"' is not assignable to type 'Custom | "fruit_apple" | "fruit_orange" | "vegetable_spinach" | "vegetable_carrot" | "other_milk" | "other_water"'. Did you mean '"vegetable_carrot"'?
+discriminatedUnionTypesOverlappingDiscriminants1.ts(131,7): error TS2322: Type '{ meal: string; audience: "earth"; }' is not assignable to type 'Target'.
+  Types of property 'audience' are incompatible.
+    Type '"earth"' is not assignable to type '"mars" | "jupiter"'.
+
+
+==== discriminatedUnionTypesOverlappingDiscriminants1.ts (8 errors) ====
+    // https://github.com/microsoft/TypeScript/issues/57231
+
+    type Food = "apple" | "orange";
+    type Vegetable = "spinach" | "carrot";
+    type Other = "milk" | "water";
+    type Custom = "air" | "soil";
+
+    type Target =
+      | {
+          audience: "earth";
+          meal:
+            | Custom
+            | `fruit_${Food}`
+            | `vegetable_${Vegetable}`
+            | `other_${Other}`;
+        }
+      | {
+          audience: "mars" | "jupiter";
+          meal: string;
+        };
+
+    const target1: Target = {
+      audience: "earth",
+      meal: `vegetable_carrot`,
+    };
+
+    const target2: Target = {
+      meal: `vegetable_carrot`,
+      audience: "earth",
+    };
+
+    const typedVegetableWithInitializer: Vegetable = 'carrot';
+
+    const target3: Target = {
+      audience: "earth",
+      meal: `vegetable_${typedVegetableWithInitializer}`,
+    };
+
+    const target4: Target = {
+      meal: `vegetable_${typedVegetableWithInitializer}`,
+      audience: "earth",
+    };
+
+    const typedCarrotWithInitializer: "carrot" = 'carrot';
+
+    const target5: Target = {
+      audience: "earth",
+      meal: `vegetable_${typedCarrotWithInitializer}`,
+    };
+
+    const target6: Target = {
+      meal: `vegetable_${typedCarrotWithInitializer}`,
+      audience: "earth",
+    };
+
+    const carrotInitializer = 'carrot';
+
+    const target7: Target = {
+      audience: "earth",
+      meal: `vegetable_${carrotInitializer}`,
+    };
+
+    const target8: Target = {
+      meal: `vegetable_${carrotInitializer}`,
+      audience: "earth",
+    };
+
+    declare const vegetable: Vegetable;
+
+    const target9: Target = {
+      audience: "earth",
+      meal: `vegetable_${vegetable}`,
+    };
+
+    const target10: Target = {
+      meal: `vegetable_${vegetable}`,
+      audience: "earth",
+    };
+
+    const typedNonVegetableWithInitializer: "cow" | "pig" = "cow";
+
+    // error
+    const target11: Target = {
+          ~~~~~~~~
+!!! error TS2322: Type '{ audience: "earth"; meal: "vegetable_cow"; }' is not assignable to type 'Target'.
+!!! error TS2322:   Types of property 'meal' are incompatible.
+!!! error TS2322:     Type '"vegetable_cow"' is not assignable to type 'Custom | "fruit_apple" | "fruit_orange" | "vegetable_spinach" | "vegetable_carrot" | "other_milk" | "other_water"'. Did you mean '"vegetable_carrot"'?
+      audience: "earth",
+      meal: `vegetable_${typedNonVegetableWithInitializer}`,
+    };
+
+    // error
+    const target12: Target = {
+          ~~~~~~~~
+!!! error TS2322: Type '{ meal: string; audience: "earth"; }' is not assignable to type 'Target'.
+!!! error TS2322:   Types of property 'audience' are incompatible.
+!!! error TS2322:     Type '"earth"' is not assignable to type '"mars" | "jupiter"'.
+      meal: `vegetable_${typedNonVegetableWithInitializer}`,
+      audience: "earth",
+    };
+
+    const typedCowWithInitializer: "cow" = "cow";
+
+    // error
+    const target13: Target = {
+          ~~~~~~~~
+!!! error TS2322: Type '{ audience: "earth"; meal: "vegetable_cow"; }' is not assignable to type 'Target'.
+!!! error TS2322:   Types of property 'meal' are incompatible.
+!!! error TS2322:     Type '"vegetable_cow"' is not assignable to type 'Custom | "fruit_apple" | "fruit_orange" | "vegetable_spinach" | "vegetable_carrot" | "other_milk" | "other_water"'. Did you mean '"vegetable_carrot"'?
+      audience: "earth",
+      meal: `vegetable_${typedCowWithInitializer}`,
+    };
+
+    // error
+    const target14: Target = {
+          ~~~~~~~~
+!!! error TS2322: Type '{ meal: string; audience: "earth"; }' is not assignable to type 'Target'.
+!!! error TS2322:   Types of property 'audience' are incompatible.
+!!! error TS2322:     Type '"earth"' is not assignable to type '"mars" | "jupiter"'.
+      meal: `vegetable_${typedCowWithInitializer}`,
+      audience: "earth",
+    };
+
+    const cowInitializer = "cow";
+
+    // error
+    const target15: Target = {
+          ~~~~~~~~
+!!! error TS2322: Type '{ audience: "earth"; meal: "vegetable_cow"; }' is not assignable to type 'Target'.
+!!! error TS2322:   Types of property 'meal' are incompatible.
+!!! error TS2322:     Type '"vegetable_cow"' is not assignable to type 'Custom | "fruit_apple" | "fruit_orange" | "vegetable_spinach" | "vegetable_carrot" | "other_milk" | "other_water"'. Did you mean '"vegetable_carrot"'?
+      audience: "earth",
+      meal: `vegetable_${cowInitializer}`,
+    };
+
+    // error
+    const target16: Target = {
+          ~~~~~~~~
+!!! error TS2322: Type '{ meal: string; audience: "earth"; }' is not assignable to type 'Target'.
+!!! error TS2322:   Types of property 'audience' are incompatible.
+!!! error TS2322:     Type '"earth"' is not assignable to type '"mars" | "jupiter"'.
+      meal: `vegetable_${cowInitializer}`,
+      audience: "earth",
+    };
+
+    declare const nonVegetable: "cow" | "pig";
+
+    // error
+    const target17: Target = {
+          ~~~~~~~~
+!!! error TS2322: Type '{ audience: "earth"; meal: "vegetable_cow" | "vegetable_pig"; }' is not assignable to type 'Target'.
+!!! error TS2322:   Types of property 'meal' are incompatible.
+!!! error TS2322:     Type '"vegetable_cow" | "vegetable_pig"' is not assignable to type 'Custom | "fruit_apple" | "fruit_orange" | "vegetable_spinach" | "vegetable_carrot" | "other_milk" | "other_water"'.
+!!! error TS2322:       Type '"vegetable_cow"' is not assignable to type 'Custom | "fruit_apple" | "fruit_orange" | "vegetable_spinach" | "vegetable_carrot" | "other_milk" | "other_water"'. Did you mean '"vegetable_carrot"'?
+      audience: "earth",
+      meal: `vegetable_${nonVegetable}`,
+    };
+
+    // error
+    const target18: Target = {
+          ~~~~~~~~
+!!! error TS2322: Type '{ meal: string; audience: "earth"; }' is not assignable to type 'Target'.
+!!! error TS2322:   Types of property 'audience' are incompatible.
+!!! error TS2322:     Type '"earth"' is not assignable to type '"mars" | "jupiter"'.
+      meal: `vegetable_${nonVegetable}`,
+      audience: "earth",
+    };
+