Merge pull request #24196 from AnthonyLatsis/diag-proto-multiple-superclass

Diag: Correct message for protocols with multiple superclass requirements

Author: slavapestov

include/swift/AST/DiagnosticsSema.def

@@ -2049,8 +2049,9 @@ NOTE(same_type_redundancy_here,none,
      "inferred from type here}0",
      (unsigned, Type, Type))
 ERROR(requires_superclass_conflict,none,
-      "%select{generic parameter |protocol |}0%1 cannot be a subclass of both "
-      "%2 and %3", (unsigned, Type, Type, Type))
+      "%select{generic parameter %1 cannot|protocol %1 cannot require 'Self' to|" 
+      "%1 cannot}0 be a subclass of both %2 and %3",
+      (unsigned, Type, Type, Type))
 WARNING(redundant_superclass_constraint,none,
         "redundant superclass constraint %0 : %1", (Type, Type))
 NOTE(superclass_redundancy_here,none,

test/Generics/superclass_constraint.swift

@@ -94,7 +94,7 @@ func superclassConformance3<T>(t: T) where T : C, T : P4, T : C2 {}
 
 protocol P5: A { }
 
-protocol P6: A, Other { } // expected-error {{protocol 'P6' cannot be a subclass of both 'Other' and 'A'}}
+protocol P6: A, Other { } // expected-error {{protocol 'P6' cannot require 'Self' to be a subclass of both 'Other' and 'A'}}
 // expected-error@-1{{multiple inheritance from classes 'A' and 'Other'}}
 // expected-note@-2 {{superclass constraint 'Self' : 'A' written here}}
 

test/IDE/print_ast_tc_decls_errors.swift

@@ -155,7 +155,7 @@ protocol ProtocolWithInheritance4 : FooClass, FooProtocol {}
 // NO-TYREPR: {{^}}protocol ProtocolWithInheritance4 : FooClass, FooProtocol {{{$}}
 // TYREPR: {{^}}protocol ProtocolWithInheritance4 : FooClass, FooProtocol {{{$}}
 
-protocol ProtocolWithInheritance5 : FooClass, BarClass {} // expected-error{{multiple inheritance from classes 'FooClass' and 'BarClass'}} expected-error{{protocol 'ProtocolWithInheritance5' cannot be a subclass of both 'BarClass' and 'FooClass'}} // expected-note{{superclass constraint 'Self' : 'FooClass' written here}}
+protocol ProtocolWithInheritance5 : FooClass, BarClass {} // expected-error{{multiple inheritance from classes 'FooClass' and 'BarClass'}} expected-error{{protocol 'ProtocolWithInheritance5' cannot require 'Self' to be a subclass of both 'BarClass' and 'FooClass'}} // expected-note{{superclass constraint 'Self' : 'FooClass' written here}}
 // NO-TYREPR: {{^}}protocol ProtocolWithInheritance5 : <<error type>>, <<error type>> {{{$}}
 // TYREPR: {{^}}protocol ProtocolWithInheritance5 : FooClass, BarClass {{{$}}