Revert PR 55371 (#58702)

src/compiler/checker.ts

@@ -18087,16 +18087,6 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         if (contains(types, wildcardType)) {
             return wildcardType;
         }
-        if (
-            texts.length === 2 && texts[0] === "" && texts[1] === ""
-            // literals (including string enums) are stringified below
-            && !(types[0].flags & TypeFlags.Literal)
-            // infer T extends StringLike can't be unwrapped eagerly
-            && !types[0].symbol?.declarations?.some(d => d.parent.kind === SyntaxKind.InferType)
-            && isTypeAssignableTo(types[0], stringType)
-        ) {
-            return types[0];
-        }
         const newTypes: Type[] = [];
         const newTexts: string[] = [];
         let text = texts[0];

tests/baselines/reference/numericStringLiteralTypes.types

@@ -14,12 +14,12 @@ type T2 = string & `${bigint}`;  // `${bigint}
 >   : ^^^^^^^^^^^
 
 type T3<T extends string> = string & `${T}`;  // `${T}
->T3 : T
->   : ^
+>T3 : `${T}`
+>   : ^^^^^^
 
 type T4<T extends string> = string & `${Capitalize<`${T}`>}`;  // `${Capitalize<T>}`
->T4 : Capitalize<T>
->   : ^^^^^^^^^^^^^
+>T4 : `${Capitalize<T>}`
+>   : ^^^^^^^^^^^^^^^^^^
 
 function f1(a: boolean[], x: `${number}`) {
 >f1 : (a: boolean[], x: `${number}`) => void

tests/baselines/reference/recursiveConditionalCrash4.types

@@ -1,8 +1,5 @@
 //// [tests/cases/compiler/recursiveConditionalCrash4.ts] ////
 
-=== Performance Stats ===
-Instantiation count: 2,500
-
 === recursiveConditionalCrash4.ts ===
 // Repros from #53783
 

tests/baselines/reference/templateLiteralIntersection.types

@@ -25,8 +25,8 @@ type OriginA1 = `${A}`
 >         : ^^^
 
 type OriginA2 = `${MixA}`
->OriginA2 : MixA
->         : ^^^^
+>OriginA2 : `${MixA}`
+>         : ^^^^^^^^^
 
 type B = `${typeof a}`
 >B : "a"
@@ -45,8 +45,8 @@ type OriginB1 = `${B}`
 >         : ^^^
 
 type OriginB2 = `${MixB}`
->OriginB2 : MixB
->         : ^^^^
+>OriginB2 : `${MixB}`
+>         : ^^^^^^^^^
 
 type MixC = { foo: string } & A
 >MixC : MixC
@@ -55,20 +55,20 @@ type MixC = { foo: string } & A
 >    : ^^^^^^
 
 type OriginC = `${MixC}`
->OriginC : MixC
->        : ^^^^
+>OriginC : `${MixC}`
+>        : ^^^^^^^^^
 
 type MixD<T extends string> =
->MixD : T & { foo: string; }
->     : ^^^^^^^^^^^      ^^^
+>MixD : `${T & { foo: string; }}`
+>     : ^^^^^^^^^^^^^^      ^^^^^
 
     `${T & { foo: string }}`
 >foo : string
 >    : ^^^^^^
 
 type OriginD = `${MixD<A & { foo: string }> & { foo: string }}`;
->OriginD : "a" & { foo: string; } & { foo: string; } & { foo: string; }
->        : ^^^^^^^^^^^^^      ^^^^^^^^^^^^^      ^^^^^^^^^^^^^      ^^^
+>OriginD : `${`${"a" & { foo: string; } & { foo: string; }}` & { foo: string; }}`
+>        : ^^^^^^^^^^^^^^^^^^^      ^^^^^^^^^^^^^      ^^^^^^^^^^^^^^^      ^^^^^
 >foo : string
 >    : ^^^^^^
 >foo : string

tests/baselines/reference/templateLiteralIntersection3.types

@@ -47,8 +47,8 @@ options1[`foo/${path}`] = false;
 
 // Lowercase<`foo/${Path}`> => `foo/${Lowercase<Path>}`
 declare const lowercasePath: Lowercase<`foo/${Path}`>;
->lowercasePath : `foo/${Lowercase<Path>}`
->              : ^^^^^^^^^^^^^^^^^^^^^^^^
+>lowercasePath : `foo/${Lowercase<`${Path}`>}`
+>              : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 options1[lowercasePath] = false;
 >options1[lowercasePath] = false : false
@@ -57,8 +57,8 @@ options1[lowercasePath] = false;
 >                        : ^^^^^^^
 >options1 : { prop: number; } & { [k: string]: boolean; }
 >         : ^^^^^^^^      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
->lowercasePath : `foo/${Lowercase<Path>}`
->              : ^^^^^^^^^^^^^^^^^^^^^^^^
+>lowercasePath : `foo/${Lowercase<`${Path}`>}`
+>              : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 >false : false
 >      : ^^^^^
 

tests/baselines/reference/templateLiteralTypes5.errors.txt

@@ -0,0 +1,50 @@
+templateLiteralTypes5.ts(10,7): error TS2322: Type '<T0 extends "a" | "b">(x: `${T0}`) => TypeMap[T0]' is not assignable to type 'F2'.
+  Type 'TypeMap[T2]' is not assignable to type 'TypeMap[`${T2}`]'.
+    Type 'T2' is not assignable to type '`${T2}`'.
+      Type '"a" | "b"' is not assignable to type '`${T2}`'.
+        Type '"a"' is not assignable to type '`${T2}`'.
+templateLiteralTypes5.ts(13,11): error TS2322: Type 'T3' is not assignable to type '`${T3}`'.
+  Type '"a" | "b"' is not assignable to type '`${T3}`'.
+    Type '"a"' is not assignable to type '`${T3}`'.
+templateLiteralTypes5.ts(14,11): error TS2322: Type '`${T3}`' is not assignable to type 'T3'.
+  '`${T3}`' is assignable to the constraint of type 'T3', but 'T3' could be instantiated with a different subtype of constraint '"a" | "b"'.
+    Type '"a" | "b"' is not assignable to type 'T3'.
+      '"a" | "b"' is assignable to the constraint of type 'T3', but 'T3' could be instantiated with a different subtype of constraint '"a" | "b"'.
+        Type '"a"' is not assignable to type 'T3'.
+          '"a"' is assignable to the constraint of type 'T3', but 'T3' could be instantiated with a different subtype of constraint '"a" | "b"'.
+
+
+==== templateLiteralTypes5.ts (3 errors) ====
+    // https://github.com/microsoft/TypeScript/issues/55364
+    interface TypeMap {
+      a: "A";
+      b: "B";
+    }
+    declare const f: <T0 extends "a" | "b">(x: `${T0}`) => TypeMap[T0];
+    type F1 = <T1 extends "a" | "b">(x: `${T1}`) => TypeMap[T1];
+    const f1: F1 = f; 
+    type F2 = <T2 extends 'a' | 'b'>(x: `${T2}`) => TypeMap[`${T2}`]
+    const f2: F2 = f
+          ~~
+!!! error TS2322: Type '<T0 extends "a" | "b">(x: `${T0}`) => TypeMap[T0]' is not assignable to type 'F2'.
+!!! error TS2322:   Type 'TypeMap[T2]' is not assignable to type 'TypeMap[`${T2}`]'.
+!!! error TS2322:     Type 'T2' is not assignable to type '`${T2}`'.
+!!! error TS2322:       Type '"a" | "b"' is not assignable to type '`${T2}`'.
+!!! error TS2322:         Type '"a"' is not assignable to type '`${T2}`'.
+
+    function f3<T3 extends "a" | "b">(x: T3) {
+        const test1: `${T3}` = x    
+              ~~~~~
+!!! error TS2322: Type 'T3' is not assignable to type '`${T3}`'.
+!!! error TS2322:   Type '"a" | "b"' is not assignable to type '`${T3}`'.
+!!! error TS2322:     Type '"a"' is not assignable to type '`${T3}`'.
+        const test2: T3 = "" as `${T3}`;    
+              ~~~~~
+!!! error TS2322: Type '`${T3}`' is not assignable to type 'T3'.
+!!! error TS2322:   '`${T3}`' is assignable to the constraint of type 'T3', but 'T3' could be instantiated with a different subtype of constraint '"a" | "b"'.
+!!! error TS2322:     Type '"a" | "b"' is not assignable to type 'T3'.
+!!! error TS2322:       '"a" | "b"' is assignable to the constraint of type 'T3', but 'T3' could be instantiated with a different subtype of constraint '"a" | "b"'.
+!!! error TS2322:         Type '"a"' is not assignable to type 'T3'.
+!!! error TS2322:           '"a"' is assignable to the constraint of type 'T3', but 'T3' could be instantiated with a different subtype of constraint '"a" | "b"'.
+    }
+

tests/baselines/reference/templateLiteralTypes5.types

@@ -14,14 +14,14 @@ interface TypeMap {
 declare const f: <T0 extends "a" | "b">(x: `${T0}`) => TypeMap[T0];
 >f : <T0 extends "a" | "b">(x: `${T0}`) => TypeMap[T0]
 >  : ^  ^^^^^^^^^         ^^ ^^       ^^^^^           
->x : T0
->  : ^^
+>x : `${T0}`
+>  : ^^^^^^^
 
 type F1 = <T1 extends "a" | "b">(x: `${T1}`) => TypeMap[T1];
 >F1 : F1
 >   : ^^
->x : T1
->  : ^^
+>x : `${T1}`
+>  : ^^^^^^^
 
 const f1: F1 = f; 
 >f1 : F1
@@ -32,8 +32,8 @@ const f1: F1 = f;
 type F2 = <T2 extends 'a' | 'b'>(x: `${T2}`) => TypeMap[`${T2}`]
 >F2 : F2
 >   : ^^
->x : T2
->  : ^^
+>x : `${T2}`
+>  : ^^^^^^^
 
 const f2: F2 = f
 >f2 : F2
@@ -48,16 +48,16 @@ function f3<T3 extends "a" | "b">(x: T3) {
 >  : ^^
 
     const test1: `${T3}` = x    
->test1 : T3
->      : ^^
+>test1 : `${T3}`
+>      : ^^^^^^^
 >x : T3
 >  : ^^
 
     const test2: T3 = "" as `${T3}`;    
 >test2 : T3
 >      : ^^
->"" as `${T3}` : T3
->              : ^^
+>"" as `${T3}` : `${T3}`
+>              : ^^^^^^^
 >"" : ""
 >   : ^^
 }

tests/baselines/reference/templateLiteralTypes8.symbols

@@ -0,0 +1,27 @@
+//// [tests/cases/conformance/types/literal/templateLiteralTypes8.ts] ////
+
+=== templateLiteralTypes8.ts ===
+const enum E {
+>E : Symbol(E, Decl(templateLiteralTypes8.ts, 0, 0))
+
+  a = "a",
+>a : Symbol(E.a, Decl(templateLiteralTypes8.ts, 0, 14))
+
+  b = "b",
+>b : Symbol(E.b, Decl(templateLiteralTypes8.ts, 1, 10))
+}
+
+type Stringify<T extends string> = `${T}`;
+>Stringify : Symbol(Stringify, Decl(templateLiteralTypes8.ts, 3, 1))
+>T : Symbol(T, Decl(templateLiteralTypes8.ts, 5, 15))
+>T : Symbol(T, Decl(templateLiteralTypes8.ts, 5, 15))
+
+let z1: `${E}` = "a";
+>z1 : Symbol(z1, Decl(templateLiteralTypes8.ts, 7, 3))
+>E : Symbol(E, Decl(templateLiteralTypes8.ts, 0, 0))
+
+let z2: Stringify<E> = "a";
+>z2 : Symbol(z2, Decl(templateLiteralTypes8.ts, 8, 3))
+>Stringify : Symbol(Stringify, Decl(templateLiteralTypes8.ts, 3, 1))
+>E : Symbol(E, Decl(templateLiteralTypes8.ts, 0, 0))
+

tests/baselines/reference/templateLiteralTypes8.types

@@ -0,0 +1,36 @@
+//// [tests/cases/conformance/types/literal/templateLiteralTypes8.ts] ////
+
+=== templateLiteralTypes8.ts ===
+const enum E {
+>E : E
+>  : ^
+
+  a = "a",
+>a : E.a
+>  : ^^^
+>"a" : "a"
+>    : ^^^
+
+  b = "b",
+>b : E.b
+>  : ^^^
+>"b" : "b"
+>    : ^^^
+}
+
+type Stringify<T extends string> = `${T}`;
+>Stringify : `${T}`
+>          : ^^^^^^
+
+let z1: `${E}` = "a";
+>z1 : "a" | "b"
+>   : ^^^^^^^^^
+>"a" : "a"
+>    : ^^^
+
+let z2: Stringify<E> = "a";
+>z2 : "a" | "b"
+>   : ^^^^^^^^^
+>"a" : "a"
+>    : ^^^
+

tests/cases/conformance/types/literal/templateLiteralTypes8.ts

@@ -0,0 +1,12 @@
+// @strict: true
+// @noEmit: true
+
+const enum E {
+  a = "a",
+  b = "b",
+}
+
+type Stringify<T extends string> = `${T}`;
+
+let z1: `${E}` = "a";
+let z2: Stringify<E> = "a";