Remove the narrow-to-fresh rule added with boolean literals

src/compiler/checker.ts

@@ -14208,10 +14208,7 @@ namespace ts {
                 if (assignedType.flags & TypeFlags.Never) {
                     return assignedType;
                 }
-                let reducedType = filterType(declaredType, t => typeMaybeAssignableTo(assignedType, t));
-                if (assignedType.flags & (TypeFlags.FreshLiteral | TypeFlags.Literal)) {
-                    reducedType = mapType(reducedType, getFreshTypeOfLiteralType); // Ensure that if the assignment is a fresh type, that we narrow to fresh types
-                }
+                const reducedType = filterType(declaredType, t => typeMaybeAssignableTo(assignedType, t));
                 // Our crude heuristic produces an invalid result in some cases: see GH#26130.
                 // For now, when that happens, we give up and don't narrow at all.  (This also
                 // means we'll never narrow for erroneous assignments where the assigned type

tests/baselines/reference/commaOperatorWithSecondOperandBooleanType.types

@@ -122,14 +122,14 @@ OBJECT = [1, 2, 3], BOOLEAN = false;
 >false : false
 
 var resultIsBoolean6 = (null, BOOLEAN);
->resultIsBoolean6 : boolean
+>resultIsBoolean6 : false
 >(null, BOOLEAN) : false
 >null, BOOLEAN : false
 >null : null
 >BOOLEAN : false
 
 var resultIsBoolean7 = (ANY = undefined, BOOLEAN);
->resultIsBoolean7 : boolean
+>resultIsBoolean7 : false
 >(ANY = undefined, BOOLEAN) : false
 >ANY = undefined, BOOLEAN : false
 >ANY = undefined : undefined

tests/baselines/reference/declarationEmitDestructuringObjectLiteralPattern.js

@@ -55,9 +55,9 @@ declare var x11: number, y11: string, z11: boolean;
 declare function f15(): {
     a4: string;
     b4: number;
-    c4: boolean;
+    c4: true;
 };
-declare var a4: string, b4: number, c4: boolean;
+declare var a4: string, b4: number, c4: true;
 declare module m {
-    var a4: string, b4: number, c4: boolean;
+    var a4: string, b4: number, c4: true;
 }

tests/baselines/reference/declarationEmitDestructuringObjectLiteralPattern.types

@@ -82,7 +82,7 @@ var { a: x11, b: { a: y11, b: { a: z11 }}} = { a: 1, b: { a: "hello", b: { a: tr
 >true : true
 
 function f15() {
->f15 : () => { a4: string; b4: number; c4: boolean; }
+>f15 : () => { a4: string; b4: number; c4: true; }
 
     var a4 = "hello";
 >a4 : string
@@ -97,17 +97,17 @@ function f15() {
 >true : true
 
     return { a4, b4, c4 };
->{ a4, b4, c4 } : { a4: string; b4: number; c4: boolean; }
+>{ a4, b4, c4 } : { a4: string; b4: number; c4: true; }
 >a4 : string
 >b4 : number
->c4 : boolean
+>c4 : true
 }
 var { a4, b4, c4 } = f15();
 >a4 : string
 >b4 : number
->c4 : boolean
->f15() : { a4: string; b4: number; c4: boolean; }
->f15 : () => { a4: string; b4: number; c4: boolean; }
+>c4 : true
+>f15() : { a4: string; b4: number; c4: true; }
+>f15 : () => { a4: string; b4: number; c4: true; }
 
 module m {
 >m : typeof m
@@ -115,7 +115,7 @@ module m {
     export var { a4, b4, c4 } = f15();
 >a4 : string
 >b4 : number
->c4 : boolean
->f15() : { a4: string; b4: number; c4: boolean; }
->f15 : () => { a4: string; b4: number; c4: boolean; }
+>c4 : true
+>f15() : { a4: string; b4: number; c4: true; }
+>f15 : () => { a4: string; b4: number; c4: true; }
 }

tests/baselines/reference/declarationEmitDestructuringObjectLiteralPattern2.js

@@ -34,9 +34,9 @@ declare var x11: number, y11: string, z11: boolean;
 declare function f15(): {
     a4: string;
     b4: number;
-    c4: boolean;
+    c4: true;
 };
-declare var a4: string, b4: number, c4: boolean;
+declare var a4: string, b4: number, c4: true;
 declare module m {
-    var a4: string, b4: number, c4: boolean;
+    var a4: string, b4: number, c4: true;
 }

tests/baselines/reference/declarationEmitDestructuringObjectLiteralPattern2.types

@@ -21,7 +21,7 @@ var { a: x11, b: { a: y11, b: { a: z11 }}} = { a: 1, b: { a: "hello", b: { a: tr
 >true : true
 
 function f15() {
->f15 : () => { a4: string; b4: number; c4: boolean; }
+>f15 : () => { a4: string; b4: number; c4: true; }
 
     var a4 = "hello";
 >a4 : string
@@ -36,17 +36,17 @@ function f15() {
 >true : true
 
     return { a4, b4, c4 };
->{ a4, b4, c4 } : { a4: string; b4: number; c4: boolean; }
+>{ a4, b4, c4 } : { a4: string; b4: number; c4: true; }
 >a4 : string
 >b4 : number
->c4 : boolean
+>c4 : true
 }
 var { a4, b4, c4 } = f15();
 >a4 : string
 >b4 : number
->c4 : boolean
->f15() : { a4: string; b4: number; c4: boolean; }
->f15 : () => { a4: string; b4: number; c4: boolean; }
+>c4 : true
+>f15() : { a4: string; b4: number; c4: true; }
+>f15 : () => { a4: string; b4: number; c4: true; }
 
 module m {
 >m : typeof m
@@ -54,7 +54,7 @@ module m {
     export var { a4, b4, c4 } = f15();
 >a4 : string
 >b4 : number
->c4 : boolean
->f15() : { a4: string; b4: number; c4: boolean; }
->f15 : () => { a4: string; b4: number; c4: boolean; }
+>c4 : true
+>f15() : { a4: string; b4: number; c4: true; }
+>f15 : () => { a4: string; b4: number; c4: true; }
 }

tests/baselines/reference/declarationsAndAssignments.types

@@ -483,7 +483,7 @@ module M {
 }
 
 function f15() {
->f15 : () => { a: string; b: number; c: boolean; }
+>f15 : () => { a: string; b: number; c: true; }
 
     var a = "hello";
 >a : string
@@ -498,10 +498,10 @@ function f15() {
 >true : true
 
     return { a, b, c };
->{ a, b, c } : { a: string; b: number; c: boolean; }
+>{ a, b, c } : { a: string; b: number; c: true; }
 >a : string
 >b : number
->c : boolean
+>c : true
 }
 
 function f16() {
@@ -510,9 +510,9 @@ function f16() {
     var { a, b, c } = f15();
 >a : string
 >b : number
->c : boolean
->f15() : { a: string; b: number; c: boolean; }
->f15 : () => { a: string; b: number; c: boolean; }
+>c : true
+>f15() : { a: string; b: number; c: true; }
+>f15 : () => { a: string; b: number; c: true; }
 }
 
 function f17({ a = "", b = 0, c = false }) {
@@ -547,8 +547,8 @@ f17({ c: true });
 f17(f15());
 >f17(f15()) : void
 >f17 : ({ a, b, c }: { a?: string; b?: number; c?: boolean; }) => void
->f15() : { a: string; b: number; c: boolean; }
->f15 : () => { a: string; b: number; c: boolean; }
+>f15() : { a: string; b: number; c: true; }
+>f15 : () => { a: string; b: number; c: true; }
 
 function f18() {
 >f18 : () => void

tests/baselines/reference/literalFreshnessNarrowing.js

@@ -0,0 +1,14 @@
+//// [literalFreshnessNarrowing.ts]
+type XY = 'x' | 'y';
+const x: XY = 'x';
+let x2 = x;  // Shouldn't have type string
+
+const y: boolean = true;
+let y2 = y;  // Shouldn't type boolean
+
+
+//// [literalFreshnessNarrowing.js]
+var x = 'x';
+var x2 = x; // Shouldn't have type string
+var y = true;
+var y2 = y; // Shouldn't type boolean

tests/baselines/reference/literalFreshnessNarrowing.symbols

@@ -0,0 +1,19 @@
+=== tests/cases/compiler/literalFreshnessNarrowing.ts ===
+type XY = 'x' | 'y';
+>XY : Symbol(XY, Decl(literalFreshnessNarrowing.ts, 0, 0))
+
+const x: XY = 'x';
+>x : Symbol(x, Decl(literalFreshnessNarrowing.ts, 1, 5))
+>XY : Symbol(XY, Decl(literalFreshnessNarrowing.ts, 0, 0))
+
+let x2 = x;  // Shouldn't have type string
+>x2 : Symbol(x2, Decl(literalFreshnessNarrowing.ts, 2, 3))
+>x : Symbol(x, Decl(literalFreshnessNarrowing.ts, 1, 5))
+
+const y: boolean = true;
+>y : Symbol(y, Decl(literalFreshnessNarrowing.ts, 4, 5))
+
+let y2 = y;  // Shouldn't type boolean
+>y2 : Symbol(y2, Decl(literalFreshnessNarrowing.ts, 5, 3))
+>y : Symbol(y, Decl(literalFreshnessNarrowing.ts, 4, 5))
+

tests/baselines/reference/literalFreshnessNarrowing.types

@@ -0,0 +1,20 @@
+=== tests/cases/compiler/literalFreshnessNarrowing.ts ===
+type XY = 'x' | 'y';
+>XY : XY
+
+const x: XY = 'x';
+>x : XY
+>'x' : "x"
+
+let x2 = x;  // Shouldn't have type string
+>x2 : "x"
+>x : "x"
+
+const y: boolean = true;
+>y : boolean
+>true : true
+
+let y2 = y;  // Shouldn't type boolean
+>y2 : true
+>y : true
+

tests/baselines/reference/typeGuardOfFormThisMember.types

@@ -92,7 +92,7 @@ namespace Test {
 >true : true
 
 	let x = file.isFile;
->x : boolean
+>x : true
 >file.isFile : true
 >file : FileSystemObject
 >isFile : true

tests/cases/compiler/literalFreshnessNarrowing.ts

@@ -0,0 +1,6 @@
+type XY = 'x' | 'y';
+const x: XY = 'x';
+let x2 = x;  // Shouldn't have type string
+
+const y: boolean = true;
+let y2 = y;  // Shouldn't type boolean