Fix invariant generic error elaboration logic

src/compiler/checker.ts

@@ -9432,6 +9432,7 @@ namespace ts {
 
             function structuredTypeRelatedTo(source: Type, target: Type, reportErrors: boolean): Ternary {
                 let result: Ternary;
+                let originalErrorInfo: DiagnosticMessageChain;
                 const saveErrorInfo = errorInfo;
                 if (target.flags & TypeFlags.TypeParameter) {
                     // A source type { [P in keyof T]: X } is related to a target type T if X is related to T[P].
@@ -9511,6 +9512,7 @@ namespace ts {
                         // if we have indexed access types with identical index types, see if relationship holds for
                         // the two object types.
                         if (result = isRelatedTo((<IndexedAccessType>source).objectType, (<IndexedAccessType>target).objectType, reportErrors)) {
+                            errorInfo = saveErrorInfo;
                             return result;
                         }
                     }
@@ -9542,6 +9544,10 @@ namespace ts {
                             if (!(reportErrors && some(variances, v => v === Variance.Invariant))) {
                                 return Ternary.False;
                             }
+                            // We remember the original error information so we can restore it in case the structural
+                            // comparison unexpectedly succeeds. This can happen when the structural comparison result
+                            // is a Ternary.Maybe for example caused by the recursion depth limiter.
+                            originalErrorInfo = errorInfo;
                             errorInfo = saveErrorInfo;
                         }
                     }
@@ -9580,8 +9586,11 @@ namespace ts {
                             }
                         }
                         if (result) {
-                            errorInfo = saveErrorInfo;
-                            return result;
+                            if (!originalErrorInfo) {
+                                errorInfo = saveErrorInfo;
+                                return result;
+                            }
+                            errorInfo = originalErrorInfo;
                         }
                     }
                 }

tests/baselines/reference/invariantGenericErrorElaboration.errors.txt

@@ -0,0 +1,54 @@
+tests/cases/compiler/invariantGenericErrorElaboration.ts(3,7): error TS2322: Type 'Num' is not assignable to type 'Runtype<any>'.
+  Types of property 'constraint' are incompatible.
+    Type 'Constraint<Num>' is not assignable to type 'Constraint<Runtype<any>>'.
+      Types of property 'constraint' are incompatible.
+        Type 'Constraint<Constraint<Num>>' is not assignable to type 'Constraint<Constraint<Runtype<any>>>'.
+          Types of property 'constraint' are incompatible.
+            Type 'Constraint<Constraint<Constraint<Num>>>' is not assignable to type 'Constraint<Constraint<Constraint<Runtype<any>>>>'.
+              Type 'Constraint<Constraint<Runtype<any>>>' is not assignable to type 'Constraint<Constraint<Num>>'.
+                Types of property 'underlying' are incompatible.
+                  Type 'Constraint<Runtype<any>>' is not assignable to type 'Constraint<Num>'.
+tests/cases/compiler/invariantGenericErrorElaboration.ts(4,17): error TS2345: Argument of type '{ foo: Num; }' is not assignable to parameter of type '{ [_: string]: Runtype<any>; }'.
+  Property 'foo' is incompatible with index signature.
+    Type 'Num' is not assignable to type 'Runtype<any>'.
+
+
+==== tests/cases/compiler/invariantGenericErrorElaboration.ts (2 errors) ====
+    // Repro from #19746
+
+    const wat: Runtype<any> = Num;
+          ~~~
+!!! error TS2322: Type 'Num' is not assignable to type 'Runtype<any>'.
+!!! error TS2322:   Types of property 'constraint' are incompatible.
+!!! error TS2322:     Type 'Constraint<Num>' is not assignable to type 'Constraint<Runtype<any>>'.
+!!! error TS2322:       Types of property 'constraint' are incompatible.
+!!! error TS2322:         Type 'Constraint<Constraint<Num>>' is not assignable to type 'Constraint<Constraint<Runtype<any>>>'.
+!!! error TS2322:           Types of property 'constraint' are incompatible.
+!!! error TS2322:             Type 'Constraint<Constraint<Constraint<Num>>>' is not assignable to type 'Constraint<Constraint<Constraint<Runtype<any>>>>'.
+!!! error TS2322:               Type 'Constraint<Constraint<Runtype<any>>>' is not assignable to type 'Constraint<Constraint<Num>>'.
+!!! error TS2322:                 Types of property 'underlying' are incompatible.
+!!! error TS2322:                   Type 'Constraint<Runtype<any>>' is not assignable to type 'Constraint<Num>'.
+    const Foo = Obj({ foo: Num })
+                    ~~~~~~~~~~~~
+!!! error TS2345: Argument of type '{ foo: Num; }' is not assignable to parameter of type '{ [_: string]: Runtype<any>; }'.
+!!! error TS2345:   Property 'foo' is incompatible with index signature.
+!!! error TS2345:     Type 'Num' is not assignable to type 'Runtype<any>'.
+
+    interface Runtype<A> {
+      constraint: Constraint<this>
+      witness: A
+    }
+
+    interface Num extends Runtype<number> {
+      tag: 'number'
+    }
+    declare const Num: Num
+
+    interface Obj<O extends { [_ in string]: Runtype<any> }> extends Runtype<{[K in keyof O]: O[K]['witness'] }> {}
+    declare function Obj<O extends { [_: string]: Runtype<any> }>(fields: O): Obj<O>;
+
+    interface Constraint<A extends Runtype<any>> extends Runtype<A['witness']> {
+      underlying: A,
+      check: (x: A['witness']) => void,
+    }
+

tests/baselines/reference/invariantGenericErrorElaboration.js

@@ -0,0 +1,30 @@
+//// [invariantGenericErrorElaboration.ts]
+// Repro from #19746
+
+const wat: Runtype<any> = Num;
+const Foo = Obj({ foo: Num })
+
+interface Runtype<A> {
+  constraint: Constraint<this>
+  witness: A
+}
+
+interface Num extends Runtype<number> {
+  tag: 'number'
+}
+declare const Num: Num
+
+interface Obj<O extends { [_ in string]: Runtype<any> }> extends Runtype<{[K in keyof O]: O[K]['witness'] }> {}
+declare function Obj<O extends { [_: string]: Runtype<any> }>(fields: O): Obj<O>;
+
+interface Constraint<A extends Runtype<any>> extends Runtype<A['witness']> {
+  underlying: A,
+  check: (x: A['witness']) => void,
+}
+
+
+//// [invariantGenericErrorElaboration.js]
+"use strict";
+// Repro from #19746
+var wat = Num;
+var Foo = Obj({ foo: Num });

tests/baselines/reference/invariantGenericErrorElaboration.symbols

@@ -0,0 +1,76 @@
+=== tests/cases/compiler/invariantGenericErrorElaboration.ts ===
+// Repro from #19746
+
+const wat: Runtype<any> = Num;
+>wat : Symbol(wat, Decl(invariantGenericErrorElaboration.ts, 2, 5))
+>Runtype : Symbol(Runtype, Decl(invariantGenericErrorElaboration.ts, 3, 29))
+>Num : Symbol(Num, Decl(invariantGenericErrorElaboration.ts, 8, 1), Decl(invariantGenericErrorElaboration.ts, 13, 13))
+
+const Foo = Obj({ foo: Num })
+>Foo : Symbol(Foo, Decl(invariantGenericErrorElaboration.ts, 3, 5))
+>Obj : Symbol(Obj, Decl(invariantGenericErrorElaboration.ts, 13, 22), Decl(invariantGenericErrorElaboration.ts, 15, 111))
+>foo : Symbol(foo, Decl(invariantGenericErrorElaboration.ts, 3, 17))
+>Num : Symbol(Num, Decl(invariantGenericErrorElaboration.ts, 8, 1), Decl(invariantGenericErrorElaboration.ts, 13, 13))
+
+interface Runtype<A> {
+>Runtype : Symbol(Runtype, Decl(invariantGenericErrorElaboration.ts, 3, 29))
+>A : Symbol(A, Decl(invariantGenericErrorElaboration.ts, 5, 18))
+
+  constraint: Constraint<this>
+>constraint : Symbol(Runtype.constraint, Decl(invariantGenericErrorElaboration.ts, 5, 22))
+>Constraint : Symbol(Constraint, Decl(invariantGenericErrorElaboration.ts, 16, 81))
+
+  witness: A
+>witness : Symbol(Runtype.witness, Decl(invariantGenericErrorElaboration.ts, 6, 30))
+>A : Symbol(A, Decl(invariantGenericErrorElaboration.ts, 5, 18))
+}
+
+interface Num extends Runtype<number> {
+>Num : Symbol(Num, Decl(invariantGenericErrorElaboration.ts, 8, 1), Decl(invariantGenericErrorElaboration.ts, 13, 13))
+>Runtype : Symbol(Runtype, Decl(invariantGenericErrorElaboration.ts, 3, 29))
+
+  tag: 'number'
+>tag : Symbol(Num.tag, Decl(invariantGenericErrorElaboration.ts, 10, 39))
+}
+declare const Num: Num
+>Num : Symbol(Num, Decl(invariantGenericErrorElaboration.ts, 8, 1), Decl(invariantGenericErrorElaboration.ts, 13, 13))
+>Num : Symbol(Num, Decl(invariantGenericErrorElaboration.ts, 8, 1), Decl(invariantGenericErrorElaboration.ts, 13, 13))
+
+interface Obj<O extends { [_ in string]: Runtype<any> }> extends Runtype<{[K in keyof O]: O[K]['witness'] }> {}
+>Obj : Symbol(Obj, Decl(invariantGenericErrorElaboration.ts, 13, 22), Decl(invariantGenericErrorElaboration.ts, 15, 111))
+>O : Symbol(O, Decl(invariantGenericErrorElaboration.ts, 15, 14))
+>_ : Symbol(_, Decl(invariantGenericErrorElaboration.ts, 15, 27))
+>Runtype : Symbol(Runtype, Decl(invariantGenericErrorElaboration.ts, 3, 29))
+>Runtype : Symbol(Runtype, Decl(invariantGenericErrorElaboration.ts, 3, 29))
+>K : Symbol(K, Decl(invariantGenericErrorElaboration.ts, 15, 75))
+>O : Symbol(O, Decl(invariantGenericErrorElaboration.ts, 15, 14))
+>O : Symbol(O, Decl(invariantGenericErrorElaboration.ts, 15, 14))
+>K : Symbol(K, Decl(invariantGenericErrorElaboration.ts, 15, 75))
+
+declare function Obj<O extends { [_: string]: Runtype<any> }>(fields: O): Obj<O>;
+>Obj : Symbol(Obj, Decl(invariantGenericErrorElaboration.ts, 13, 22), Decl(invariantGenericErrorElaboration.ts, 15, 111))
+>O : Symbol(O, Decl(invariantGenericErrorElaboration.ts, 16, 21))
+>_ : Symbol(_, Decl(invariantGenericErrorElaboration.ts, 16, 34))
+>Runtype : Symbol(Runtype, Decl(invariantGenericErrorElaboration.ts, 3, 29))
+>fields : Symbol(fields, Decl(invariantGenericErrorElaboration.ts, 16, 62))
+>O : Symbol(O, Decl(invariantGenericErrorElaboration.ts, 16, 21))
+>Obj : Symbol(Obj, Decl(invariantGenericErrorElaboration.ts, 13, 22), Decl(invariantGenericErrorElaboration.ts, 15, 111))
+>O : Symbol(O, Decl(invariantGenericErrorElaboration.ts, 16, 21))
+
+interface Constraint<A extends Runtype<any>> extends Runtype<A['witness']> {
+>Constraint : Symbol(Constraint, Decl(invariantGenericErrorElaboration.ts, 16, 81))
+>A : Symbol(A, Decl(invariantGenericErrorElaboration.ts, 18, 21))
+>Runtype : Symbol(Runtype, Decl(invariantGenericErrorElaboration.ts, 3, 29))
+>Runtype : Symbol(Runtype, Decl(invariantGenericErrorElaboration.ts, 3, 29))
+>A : Symbol(A, Decl(invariantGenericErrorElaboration.ts, 18, 21))
+
+  underlying: A,
+>underlying : Symbol(Constraint.underlying, Decl(invariantGenericErrorElaboration.ts, 18, 76))
+>A : Symbol(A, Decl(invariantGenericErrorElaboration.ts, 18, 21))
+
+  check: (x: A['witness']) => void,
+>check : Symbol(Constraint.check, Decl(invariantGenericErrorElaboration.ts, 19, 16))
+>x : Symbol(x, Decl(invariantGenericErrorElaboration.ts, 20, 10))
+>A : Symbol(A, Decl(invariantGenericErrorElaboration.ts, 18, 21))
+}
+

tests/baselines/reference/invariantGenericErrorElaboration.types

@@ -0,0 +1,78 @@
+=== tests/cases/compiler/invariantGenericErrorElaboration.ts ===
+// Repro from #19746
+
+const wat: Runtype<any> = Num;
+>wat : Runtype<any>
+>Runtype : Runtype<A>
+>Num : Num
+
+const Foo = Obj({ foo: Num })
+>Foo : any
+>Obj({ foo: Num }) : any
+>Obj : <O extends { [_: string]: Runtype<any>; }>(fields: O) => Obj<O>
+>{ foo: Num } : { foo: Num; }
+>foo : Num
+>Num : Num
+
+interface Runtype<A> {
+>Runtype : Runtype<A>
+>A : A
+
+  constraint: Constraint<this>
+>constraint : Constraint<this>
+>Constraint : Constraint<A>
+
+  witness: A
+>witness : A
+>A : A
+}
+
+interface Num extends Runtype<number> {
+>Num : Num
+>Runtype : Runtype<A>
+
+  tag: 'number'
+>tag : "number"
+}
+declare const Num: Num
+>Num : Num
+>Num : Num
+
+interface Obj<O extends { [_ in string]: Runtype<any> }> extends Runtype<{[K in keyof O]: O[K]['witness'] }> {}
+>Obj : Obj<O>
+>O : O
+>_ : _
+>Runtype : Runtype<A>
+>Runtype : Runtype<A>
+>K : K
+>O : O
+>O : O
+>K : K
+
+declare function Obj<O extends { [_: string]: Runtype<any> }>(fields: O): Obj<O>;
+>Obj : <O extends { [_: string]: Runtype<any>; }>(fields: O) => Obj<O>
+>O : O
+>_ : string
+>Runtype : Runtype<A>
+>fields : O
+>O : O
+>Obj : Obj<O>
+>O : O
+
+interface Constraint<A extends Runtype<any>> extends Runtype<A['witness']> {
+>Constraint : Constraint<A>
+>A : A
+>Runtype : Runtype<A>
+>Runtype : Runtype<A>
+>A : A
+
+  underlying: A,
+>underlying : A
+>A : A
+
+  check: (x: A['witness']) => void,
+>check : (x: A["witness"]) => void
+>x : A["witness"]
+>A : A
+}
+

tests/cases/compiler/invariantGenericErrorElaboration.ts

@@ -0,0 +1,24 @@
+// @strict: true
+
+// Repro from #19746
+
+const wat: Runtype<any> = Num;
+const Foo = Obj({ foo: Num })
+
+interface Runtype<A> {
+  constraint: Constraint<this>
+  witness: A
+}
+
+interface Num extends Runtype<number> {
+  tag: 'number'
+}
+declare const Num: Num
+
+interface Obj<O extends { [_ in string]: Runtype<any> }> extends Runtype<{[K in keyof O]: O[K]['witness'] }> {}
+declare function Obj<O extends { [_: string]: Runtype<any> }>(fields: O): Obj<O>;
+
+interface Constraint<A extends Runtype<any>> extends Runtype<A['witness']> {
+  underlying: A,
+  check: (x: A['witness']) => void,
+}