[RequirementMachine] Downgrade concrete type parameter diagnostics to a

warning.

These diagnostics are stricter in the RequirementMachine than in the GSB,
and there's code that relies on the more relaxed diagnostics in the source
compatibility suite. Downgrade these diagnostics to a warning using
warnUntilSwiftVersion(6).

Author: hborla

lib/AST/RequirementMachine/RequirementMachineRequests.cpp

@@ -908,11 +908,13 @@ InferredGenericSignatureRequestRQM::evaluate(
 
         if (canonical->isTypeParameter()) {
           ctx.Diags.diagnose(loc, diag::requires_generic_params_made_equal,
-                             genericParam, result->getSugaredType(canonical));
+                             genericParam, result->getSugaredType(canonical))
+            .warnUntilSwiftVersion(6);
         } else {
           ctx.Diags.diagnose(loc,
                              diag::requires_generic_param_made_equal_to_concrete,
-                             genericParam);
+                             genericParam)
+            .warnUntilSwiftVersion(6);
         }
       }
     }

test/Compatibility/accessibility.swift

@@ -503,7 +503,7 @@ struct DefaultGeneric<T> {}
 
 struct DefaultGenericPrivate<T: PrivateProto> {} // expected-error {{generic struct must be declared private or fileprivate because its generic parameter uses a private type}}
 struct DefaultGenericPrivate2<T: PrivateClass> {} // expected-error {{generic struct must be declared private or fileprivate because its generic parameter uses a private type}}
-struct DefaultGenericPrivateReq<T> where T == PrivateClass {} // expected-error  {{same-type requirement makes generic parameter 'T' non-generic}}
+struct DefaultGenericPrivateReq<T> where T == PrivateClass {} // expected-warning  {{same-type requirement makes generic parameter 'T' non-generic}}
 // expected-error@-1 {{generic struct must be declared private or fileprivate because its generic requirement uses a private type}}
 struct DefaultGenericPrivateReq2<T> where T: PrivateProto {} // expected-error {{generic struct must be declared private or fileprivate because its generic requirement uses a private type}}
 

test/Constraints/generic_super_constraint.swift

@@ -9,7 +9,7 @@ func foo<T>(_ x: T) -> Derived where T: Base<Int>, T: Derived {
 }
 
 // FIXME: There is no explicit same-type requirement written.
-// expected-error@+1{{same-type requirement makes generic parameter 'T' non-generic}}
+// expected-warning@+1{{same-type requirement makes generic parameter 'T' non-generic}}
 func bar<T, U>(_ x: U, y: T) -> (Derived, Int) where U: Base<T>, U: Derived {
   return (x, y)
 }

test/Generics/concrete_contraction_unrelated_typealias.swift

@@ -53,8 +53,8 @@ class ConcreteDelegateProxy {
   // CHECK-LABEL: .ConcreteDelegateProxy.init(_:_:_:)@
   // CHECK-NEXT: <P, D, Proxy where P == SomeClass, D == SomeStruct, Proxy : ConcreteDelegateProxy, Proxy : DelegateProxyType, Proxy.[DelegateProxyType]Delegate == SomeStruct, Proxy.[DelegateProxyType]Parent == SomeClass>
 
-  // expected-error@+2 {{same-type requirement makes generic parameter 'P' non-generic}}
-  // expected-error@+1 {{same-type requirement makes generic parameter 'D' non-generic}}
+  // expected-warning@+2 {{same-type requirement makes generic parameter 'P' non-generic}}
+  // expected-warning@+1 {{same-type requirement makes generic parameter 'D' non-generic}}
   init<P, D, Proxy: DelegateProxyType>(_: P, _: D, _: Proxy.Type)
     where Proxy: ConcreteDelegateProxy,
           Proxy.Parent == P,

test/Generics/function_defs.swift

@@ -301,4 +301,4 @@ func badTypeConformance7<T, U>(_: T, _: U) where T? : U { }
 
 func badSameType<T, U : GeneratesAnElement, V>(_ : T, _ : U)
   where T == U.Element, U.Element == V {}
-// expected-error@-2{{same-type requirement makes generic parameters 'V' and 'T' equivalent}}
+// expected-warning@-2{{same-type requirement makes generic parameters 'V' and 'T' equivalent}}

test/Generics/requirement_machine_diagnostics.swift

@@ -47,7 +47,7 @@ func concreteSameTypeRedundancy<T>(_: T) where Int == Int {}
 
 func concreteSameTypeRedundancy<T>(_: T) where Array<Int> == Array<T> {}
 // expected-warning@-1{{redundant same-type constraint 'Array<Int>' == 'Array<T>'}}
-// expected-error@-2{{same-type requirement makes generic parameter 'T' non-generic}}
+// expected-warning@-2{{same-type requirement makes generic parameter 'T' non-generic}}
 
 protocol P {}
 struct S: P {}
@@ -199,7 +199,7 @@ func inferred6<T : P11>(_: T) where T.Y : Hashable, T.Z == Set<T.X>, T.X == T.Y
 func typeMatcherSugar<T>(_: T) where Array<Int> == Array<T>, Array<Int> == Array<T> {}
 // expected-warning@-1 2{{redundant same-type constraint 'Array<Int>' == 'Array<T>'}}
 // expected-warning@-2{{redundant same-type constraint 'T' == 'Int'}}
-// expected-error@-3{{same-type requirement makes generic parameter 'T' non-generic}}
+// expected-warning@-3{{same-type requirement makes generic parameter 'T' non-generic}}
 
 
 struct ConcreteSelf: ConcreteProtocol {}

test/Generics/superclass_constraint_nested_type.swift

@@ -1,5 +1,5 @@
 // RUN: %target-typecheck-verify-swift
-// RUN: not %target-swift-frontend -typecheck %s -debug-generic-signatures 2>&1 | %FileCheck %s
+// RUN: %target-swift-frontend -typecheck -verify %s -debug-generic-signatures 2>&1 | %FileCheck %s
 
 // rdar://problem/39481178 - Introducing a superclass constraint does not add
 // same-type constraints on nested types
@@ -19,10 +19,10 @@ extension P {
   // CHECK-LABEL: .f1@
   // CHECK-NEXT: <Self, T where Self : C, T == Int>
   func f1<T>(_: T) where T == Q, Self : C {}
-  // expected-error@-1 {{same-type requirement makes generic parameter 'T' non-generic}}
+  // expected-warning@-1 {{same-type requirement makes generic parameter 'T' non-generic}}
 
   // CHECK-LABEL: .f2@
   // CHECK-NEXT: <Self, T where Self : C, T == Int>
   func f2<T>(_: T) where Self : C, T == Q {}
-  // expected-error@-1 {{same-type requirement makes generic parameter 'T' non-generic}}
+  // expected-warning@-1 {{same-type requirement makes generic parameter 'T' non-generic}}
 }

test/IDE/print_usrs_opaque_types.swift

@@ -7,7 +7,7 @@
 
 // CHECK: [[@LINE+1]]:{{[0-9]+}} s:14swift_ide_test0C21UnifyingGenericParams1xQrx_tq_Rszr0_lF
 func testUnifyingGenericParams<T, U>(x: T) -> some Collection where T == U {
-  // expected-error@-1 {{same-type requirement makes generic parameters 'U' and 'T' equivalent}}
+  // expected-warning@-1 {{same-type requirement makes generic parameters 'U' and 'T' equivalent}}
   return []
 }
 
@@ -18,14 +18,14 @@ func testUnifyingGenericParams2<T, U>(x: T) -> some Collection where T: Collecti
 
 // CHECK: [[@LINE+1]]:{{[0-9]+}} s:14swift_ide_test0C24ConcretizingGenericParam1xQrSi_tSiRszlF
 func testConcretizingGenericParam<T>(x: T) -> some Collection where T == Int {
-  // expected-error@-1 {{same-type requirement makes generic parameter 'T' non-generic}}
+  // expected-warning@-1 {{same-type requirement makes generic parameter 'T' non-generic}}
   return []
 }
 
 struct GenericContext<T> {
   // CHECK: [[@LINE+1]]:{{[0-9]+}} s:14swift_ide_test14GenericContextV0c8UnifyingD6Params1xQrx_tqd__RszlF
   func testUnifyingGenericParams<U>(x: T) -> some Collection where T == U {
-    // expected-error@-1 {{same-type requirement makes generic parameters 'U' and 'T' equivalent}}
+    // expected-warning@-1 {{same-type requirement makes generic parameters 'U' and 'T' equivalent}}
     return []
   }
 
@@ -36,7 +36,7 @@ struct GenericContext<T> {
 
   // CHECK: [[@LINE+1]]:{{[0-9]+}} s:14swift_ide_test14GenericContextVyQrxcqd__Rszluip
   subscript<U>(x: T) -> some Collection where T == U {
-    // expected-error@-1 {{same-type requirement makes generic parameters 'U' and 'T' equivalent}}
+    // expected-warning@-1 {{same-type requirement makes generic parameters 'U' and 'T' equivalent}}
     // CHECK: [[@LINE+1]]:{{[0-9]+}} s:14swift_ide_test14GenericContextVyQrxcqd__Rszluig
     get {
       return []

test/Sema/accessibility.swift

@@ -520,7 +520,7 @@ struct DefaultGeneric<T> {}
 
 struct DefaultGenericPrivate<T: PrivateProto> {} // expected-error {{generic struct must be declared private or fileprivate because its generic parameter uses a private type}}
 struct DefaultGenericPrivate2<T: PrivateClass> {} // expected-error {{generic struct must be declared private or fileprivate because its generic parameter uses a private type}}
-struct DefaultGenericPrivateReq<T> where T == PrivateClass {} // expected-error  {{same-type requirement makes generic parameter 'T' non-generic}}
+struct DefaultGenericPrivateReq<T> where T == PrivateClass {} // expected-warning  {{same-type requirement makes generic parameter 'T' non-generic}}
 // expected-error@-1 {{generic struct must be declared private or fileprivate because its generic requirement uses a private type}}
 struct DefaultGenericPrivateReq2<T> where T: PrivateProto {} // expected-error {{generic struct must be declared private or fileprivate because its generic requirement uses a private type}}
 

test/decl/typealias/generic.swift

@@ -33,7 +33,7 @@ typealias DS<T> = MyType<String, T>
 typealias BadA<T : Int> = MyType<String, T>  // expected-error {{type 'T' constrained to non-protocol, non-class type 'Int'}}
 
 typealias BadB<T where T == Int> = MyType<String, T>  // expected-error {{associated types must not have a generic parameter list}}
-// expected-error@-1 {{same-type requirement makes generic parameter 'T' non-generic}}
+// expected-warning@-1 {{same-type requirement makes generic parameter 'T' non-generic}}
 
 typealias BadC<T,T> = MyType<String, T>  // expected-error {{invalid redeclaration of 'T'}}
 // expected-note @-1 {{'T' previously declared here}}

test/decl/typealias/protocol.swift

@@ -254,7 +254,7 @@ protocol P9 {
   typealias A = Int
 }
 
-func testT9a<T: P9, U>(_: T, _: U) where T.A == U { } // expected-error {{same-type requirement makes generic parameter 'U' non-generic}}
+func testT9a<T: P9, U>(_: T, _: U) where T.A == U { } // expected-warning {{same-type requirement makes generic parameter 'U' non-generic}}
 func testT9b<T: P9>(_: T) where T.A == Float { } // expected-error{{no type for 'T.A' can satisfy both 'T.A == Int' and 'T.A == Float'}}