Fixed inference between type placeholders with non-string constraints in template literal types

src/compiler/checker.ts

@@ -25443,7 +25443,9 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
     function inferTypesFromTemplateLiteralType(source: Type, target: TemplateLiteralType): Type[] | undefined {
         return source.flags & TypeFlags.StringLiteral ? inferFromLiteralPartsToTemplateLiteral([(source as StringLiteralType).value], emptyArray, target) :
             source.flags & TypeFlags.TemplateLiteral ?
-            arraysEqual((source as TemplateLiteralType).texts, target.texts) ? map((source as TemplateLiteralType).types, getStringLikeTypeForType) :
+            arraysEqual((source as TemplateLiteralType).texts, target.texts) ? map((source as TemplateLiteralType).types, (s, i) => {
+                return isTypeAssignableTo(getBaseConstraintOrType(s), getBaseConstraintOrType(target.types[i])) ? s : getStringLikeTypeForType(s);
+            }) :
                 inferFromLiteralPartsToTemplateLiteral((source as TemplateLiteralType).texts, (source as TemplateLiteralType).types, target) :
             undefined;
     }

tests/baselines/reference/templateLiteralTypes7.errors.txt

@@ -0,0 +1,34 @@
+templateLiteralTypes7.ts(16,7): error TS2322: Type '<T extends 1 | 2 | 3>(x: `${T}`) => NMap[T]' is not assignable to type 'G2'.
+  Types of parameters 'x' and 'x' are incompatible.
+    Type '`${T}`' is not assignable to type '"1" | "2" | "3"'.
+      Type '"1" | "2" | "3" | "4"' is not assignable to type '"1" | "2" | "3"'.
+        Type '"4"' is not assignable to type '"1" | "2" | "3"'.
+
+
+==== templateLiteralTypes7.ts (1 errors) ====
+    // https://github.com/microsoft/TypeScript/issues/57807
+
+    interface NMap {
+      1: 'A'
+      2: 'B'
+      3: 'C'
+      4: 'D'
+    }
+
+    declare const g: <T extends 1 | 2 | 3>(x: `${T}`) => NMap[T]
+
+    type G1 = <T extends 1 | 2 | 3>(x: `${T}`) => NMap[T]
+    const g1: G1 = g; // ok
+
+    type G2 = <T extends 1 | 2 | 3 | 4>(x: `${T}`) => NMap[T]
+    const g2: G2 = g; // error
+          ~~
+!!! error TS2322: Type '<T extends 1 | 2 | 3>(x: `${T}`) => NMap[T]' is not assignable to type 'G2'.
+!!! error TS2322:   Types of parameters 'x' and 'x' are incompatible.
+!!! error TS2322:     Type '`${T}`' is not assignable to type '"1" | "2" | "3"'.
+!!! error TS2322:       Type '"1" | "2" | "3" | "4"' is not assignable to type '"1" | "2" | "3"'.
+!!! error TS2322:         Type '"4"' is not assignable to type '"1" | "2" | "3"'.
+
+    type G3 = <T extends 1 | 2>(x: `${T}`) => NMap[T]
+    const g3: G3 = g; // ok
+

tests/baselines/reference/templateLiteralTypes7.symbols

@@ -0,0 +1,68 @@
+//// [tests/cases/conformance/types/literal/templateLiteralTypes7.ts] ////
+
+=== templateLiteralTypes7.ts ===
+// https://github.com/microsoft/TypeScript/issues/57807
+
+interface NMap {
+>NMap : Symbol(NMap, Decl(templateLiteralTypes7.ts, 0, 0))
+
+  1: 'A'
+>1 : Symbol(NMap[1], Decl(templateLiteralTypes7.ts, 2, 16))
+
+  2: 'B'
+>2 : Symbol(NMap[2], Decl(templateLiteralTypes7.ts, 3, 8))
+
+  3: 'C'
+>3 : Symbol(NMap[3], Decl(templateLiteralTypes7.ts, 4, 8))
+
+  4: 'D'
+>4 : Symbol(NMap[4], Decl(templateLiteralTypes7.ts, 5, 8))
+}
+
+declare const g: <T extends 1 | 2 | 3>(x: `${T}`) => NMap[T]
+>g : Symbol(g, Decl(templateLiteralTypes7.ts, 9, 13))
+>T : Symbol(T, Decl(templateLiteralTypes7.ts, 9, 18))
+>x : Symbol(x, Decl(templateLiteralTypes7.ts, 9, 39))
+>T : Symbol(T, Decl(templateLiteralTypes7.ts, 9, 18))
+>NMap : Symbol(NMap, Decl(templateLiteralTypes7.ts, 0, 0))
+>T : Symbol(T, Decl(templateLiteralTypes7.ts, 9, 18))
+
+type G1 = <T extends 1 | 2 | 3>(x: `${T}`) => NMap[T]
+>G1 : Symbol(G1, Decl(templateLiteralTypes7.ts, 9, 60))
+>T : Symbol(T, Decl(templateLiteralTypes7.ts, 11, 11))
+>x : Symbol(x, Decl(templateLiteralTypes7.ts, 11, 32))
+>T : Symbol(T, Decl(templateLiteralTypes7.ts, 11, 11))
+>NMap : Symbol(NMap, Decl(templateLiteralTypes7.ts, 0, 0))
+>T : Symbol(T, Decl(templateLiteralTypes7.ts, 11, 11))
+
+const g1: G1 = g; // ok
+>g1 : Symbol(g1, Decl(templateLiteralTypes7.ts, 12, 5))
+>G1 : Symbol(G1, Decl(templateLiteralTypes7.ts, 9, 60))
+>g : Symbol(g, Decl(templateLiteralTypes7.ts, 9, 13))
+
+type G2 = <T extends 1 | 2 | 3 | 4>(x: `${T}`) => NMap[T]
+>G2 : Symbol(G2, Decl(templateLiteralTypes7.ts, 12, 17))
+>T : Symbol(T, Decl(templateLiteralTypes7.ts, 14, 11))
+>x : Symbol(x, Decl(templateLiteralTypes7.ts, 14, 36))
+>T : Symbol(T, Decl(templateLiteralTypes7.ts, 14, 11))
+>NMap : Symbol(NMap, Decl(templateLiteralTypes7.ts, 0, 0))
+>T : Symbol(T, Decl(templateLiteralTypes7.ts, 14, 11))
+
+const g2: G2 = g; // error
+>g2 : Symbol(g2, Decl(templateLiteralTypes7.ts, 15, 5))
+>G2 : Symbol(G2, Decl(templateLiteralTypes7.ts, 12, 17))
+>g : Symbol(g, Decl(templateLiteralTypes7.ts, 9, 13))
+
+type G3 = <T extends 1 | 2>(x: `${T}`) => NMap[T]
+>G3 : Symbol(G3, Decl(templateLiteralTypes7.ts, 15, 17))
+>T : Symbol(T, Decl(templateLiteralTypes7.ts, 17, 11))
+>x : Symbol(x, Decl(templateLiteralTypes7.ts, 17, 28))
+>T : Symbol(T, Decl(templateLiteralTypes7.ts, 17, 11))
+>NMap : Symbol(NMap, Decl(templateLiteralTypes7.ts, 0, 0))
+>T : Symbol(T, Decl(templateLiteralTypes7.ts, 17, 11))
+
+const g3: G3 = g; // ok
+>g3 : Symbol(g3, Decl(templateLiteralTypes7.ts, 18, 5))
+>G3 : Symbol(G3, Decl(templateLiteralTypes7.ts, 15, 17))
+>g : Symbol(g, Decl(templateLiteralTypes7.ts, 9, 13))
+

tests/baselines/reference/templateLiteralTypes7.types

@@ -0,0 +1,47 @@
+//// [tests/cases/conformance/types/literal/templateLiteralTypes7.ts] ////
+
+=== templateLiteralTypes7.ts ===
+// https://github.com/microsoft/TypeScript/issues/57807
+
+interface NMap {
+  1: 'A'
+>1 : "A"
+
+  2: 'B'
+>2 : "B"
+
+  3: 'C'
+>3 : "C"
+
+  4: 'D'
+>4 : "D"
+}
+
+declare const g: <T extends 1 | 2 | 3>(x: `${T}`) => NMap[T]
+>g : <T extends 1 | 2 | 3>(x: `${T}`) => NMap[T]
+>x : `${T}`
+
+type G1 = <T extends 1 | 2 | 3>(x: `${T}`) => NMap[T]
+>G1 : <T extends 1 | 2 | 3>(x: `${T}`) => NMap[T]
+>x : `${T}`
+
+const g1: G1 = g; // ok
+>g1 : G1
+>g : <T extends 1 | 2 | 3>(x: `${T}`) => NMap[T]
+
+type G2 = <T extends 1 | 2 | 3 | 4>(x: `${T}`) => NMap[T]
+>G2 : <T extends 1 | 2 | 3 | 4>(x: `${T}`) => NMap[T]
+>x : `${T}`
+
+const g2: G2 = g; // error
+>g2 : G2
+>g : <T extends 1 | 2 | 3>(x: `${T}`) => NMap[T]
+
+type G3 = <T extends 1 | 2>(x: `${T}`) => NMap[T]
+>G3 : <T extends 1 | 2>(x: `${T}`) => NMap[T]
+>x : `${T}`
+
+const g3: G3 = g; // ok
+>g3 : G3
+>g : <T extends 1 | 2 | 3>(x: `${T}`) => NMap[T]
+

tests/cases/conformance/types/literal/templateLiteralTypes7.ts

@@ -0,0 +1,23 @@
+// @strict: true
+// @target: esnext
+// @noEmit: true
+
+// https://github.com/microsoft/TypeScript/issues/57807
+
+interface NMap {
+  1: 'A'
+  2: 'B'
+  3: 'C'
+  4: 'D'
+}
+
+declare const g: <T extends 1 | 2 | 3>(x: `${T}`) => NMap[T]
+
+type G1 = <T extends 1 | 2 | 3>(x: `${T}`) => NMap[T]
+const g1: G1 = g; // ok
+
+type G2 = <T extends 1 | 2 | 3 | 4>(x: `${T}`) => NMap[T]
+const g2: G2 = g; // error
+
+type G3 = <T extends 1 | 2>(x: `${T}`) => NMap[T]
+const g3: G3 = g; // ok