Add regressions for conditional types that affect parameter variance (#30146)

Author: jack-williams

tests/baselines/reference/variance.js

@@ -0,0 +1,45 @@
+//// [variance.ts]
+// Test cases for parameter variances affected by conditional types.
+
+// Repro from #30047
+
+interface Foo<T> {
+  prop: T extends unknown ? true : false;
+}
+
+const foo = { prop: true } as const;
+const x: Foo<1> = foo;
+const y: Foo<number> = foo;
+const z: Foo<number> = x;
+
+
+// Repro from #30118
+
+class Bar<T extends string> {
+  private static instance: Bar<string>[];
+
+  cast(_name: ([T] extends [string] ? string : string)) { }
+  
+  pushThis() {
+    Bar.instance.push(this);
+  }
+}
+
+
+//// [variance.js]
+"use strict";
+// Test cases for parameter variances affected by conditional types.
+var foo = { prop: true };
+var x = foo;
+var y = foo;
+var z = x;
+// Repro from #30118
+var Bar = /** @class */ (function () {
+    function Bar() {
+    }
+    Bar.prototype.cast = function (_name) { };
+    Bar.prototype.pushThis = function () {
+        Bar.instance.push(this);
+    };
+    return Bar;
+}());

tests/baselines/reference/variance.symbols

@@ -0,0 +1,62 @@
+=== tests/cases/conformance/types/conditional/variance.ts ===
+// Test cases for parameter variances affected by conditional types.
+
+// Repro from #30047
+
+interface Foo<T> {
+>Foo : Symbol(Foo, Decl(variance.ts, 0, 0))
+>T : Symbol(T, Decl(variance.ts, 4, 14))
+
+  prop: T extends unknown ? true : false;
+>prop : Symbol(Foo.prop, Decl(variance.ts, 4, 18))
+>T : Symbol(T, Decl(variance.ts, 4, 14))
+}
+
+const foo = { prop: true } as const;
+>foo : Symbol(foo, Decl(variance.ts, 8, 5))
+>prop : Symbol(prop, Decl(variance.ts, 8, 13))
+
+const x: Foo<1> = foo;
+>x : Symbol(x, Decl(variance.ts, 9, 5))
+>Foo : Symbol(Foo, Decl(variance.ts, 0, 0))
+>foo : Symbol(foo, Decl(variance.ts, 8, 5))
+
+const y: Foo<number> = foo;
+>y : Symbol(y, Decl(variance.ts, 10, 5))
+>Foo : Symbol(Foo, Decl(variance.ts, 0, 0))
+>foo : Symbol(foo, Decl(variance.ts, 8, 5))
+
+const z: Foo<number> = x;
+>z : Symbol(z, Decl(variance.ts, 11, 5))
+>Foo : Symbol(Foo, Decl(variance.ts, 0, 0))
+>x : Symbol(x, Decl(variance.ts, 9, 5))
+
+
+// Repro from #30118
+
+class Bar<T extends string> {
+>Bar : Symbol(Bar, Decl(variance.ts, 11, 25))
+>T : Symbol(T, Decl(variance.ts, 16, 10))
+
+  private static instance: Bar<string>[];
+>instance : Symbol(Bar.instance, Decl(variance.ts, 16, 29))
+>Bar : Symbol(Bar, Decl(variance.ts, 11, 25))
+
+  cast(_name: ([T] extends [string] ? string : string)) { }
+>cast : Symbol(Bar.cast, Decl(variance.ts, 17, 41))
+>_name : Symbol(_name, Decl(variance.ts, 19, 7))
+>T : Symbol(T, Decl(variance.ts, 16, 10))
+  
+  pushThis() {
+>pushThis : Symbol(Bar.pushThis, Decl(variance.ts, 19, 59))
+
+    Bar.instance.push(this);
+>Bar.instance.push : Symbol(Array.push, Decl(lib.es5.d.ts, --, --))
+>Bar.instance : Symbol(Bar.instance, Decl(variance.ts, 16, 29))
+>Bar : Symbol(Bar, Decl(variance.ts, 11, 25))
+>instance : Symbol(Bar.instance, Decl(variance.ts, 16, 29))
+>push : Symbol(Array.push, Decl(lib.es5.d.ts, --, --))
+>this : Symbol(Bar, Decl(variance.ts, 11, 25))
+  }
+}
+

tests/baselines/reference/variance.types

@@ -0,0 +1,58 @@
+=== tests/cases/conformance/types/conditional/variance.ts ===
+// Test cases for parameter variances affected by conditional types.
+
+// Repro from #30047
+
+interface Foo<T> {
+  prop: T extends unknown ? true : false;
+>prop : T extends unknown ? true : false
+>true : true
+>false : false
+}
+
+const foo = { prop: true } as const;
+>foo : { readonly prop: true; }
+>{ prop: true } as const : { readonly prop: true; }
+>{ prop: true } : { readonly prop: true; }
+>prop : true
+>true : true
+
+const x: Foo<1> = foo;
+>x : Foo<1>
+>foo : { readonly prop: true; }
+
+const y: Foo<number> = foo;
+>y : Foo<number>
+>foo : { readonly prop: true; }
+
+const z: Foo<number> = x;
+>z : Foo<number>
+>x : Foo<1>
+
+
+// Repro from #30118
+
+class Bar<T extends string> {
+>Bar : Bar<T>
+
+  private static instance: Bar<string>[];
+>instance : Bar<string>[]
+
+  cast(_name: ([T] extends [string] ? string : string)) { }
+>cast : (_name: [T] extends [string] ? string : string) => void
+>_name : [T] extends [string] ? string : string
+  
+  pushThis() {
+>pushThis : () => void
+
+    Bar.instance.push(this);
+>Bar.instance.push(this) : number
+>Bar.instance.push : (...items: Bar<string>[]) => number
+>Bar.instance : Bar<string>[]
+>Bar : typeof Bar
+>instance : Bar<string>[]
+>push : (...items: Bar<string>[]) => number
+>this : this
+  }
+}
+

tests/cases/conformance/types/conditional/variance.ts

@@ -0,0 +1,27 @@
+// @strict: true
+
+// Test cases for parameter variances affected by conditional types.
+
+// Repro from #30047
+
+interface Foo<T> {
+  prop: T extends unknown ? true : false;
+}
+
+const foo = { prop: true } as const;
+const x: Foo<1> = foo;
+const y: Foo<number> = foo;
+const z: Foo<number> = x;
+
+
+// Repro from #30118
+
+class Bar<T extends string> {
+  private static instance: Bar<string>[];
+
+  cast(_name: ([T] extends [string] ? string : string)) { }
+  
+  pushThis() {
+    Bar.instance.push(this);
+  }
+}