Merge pull request #75486 from xedin/fix-unsed-decl-in-generic-spec-diagnostic

[Diagnostics] Add a note to invalid generic function specialization d…

Author: xedin

lib/Sema/CSDiagnostics.cpp

@@ -9370,6 +9370,7 @@ bool ConcreteTypeSpecialization::diagnoseAsError() {
 
 bool GenericFunctionSpecialization::diagnoseAsError() {
   emitDiagnostic(diag::cannot_explicitly_specialize_generic_function);
+  emitDiagnosticAt(Decl, diag::decl_declared_here, Decl);
   return true;
 }
 

test/Parse/generic_disambiguation.swift

@@ -19,7 +19,7 @@ protocol Fungible {}
 func meta<T>(_ m: T.Type) {}
 func meta2<T>(_ m: T.Type, _ x: Int) {}
 
-func generic<T>(_ x: T) {}
+func generic<T>(_ x: T) {} // expected-note {{'generic' declared here}}
 
 var a, b, c, d : Int
 

test/Sema/generic-arg-list.swift renamed to test/Sema/generic_specialization.swift

@@ -9,7 +9,7 @@ extension Int {
   func baz() -> Int {}
   func baz(_ x: Int = 0) -> Int {}
 
-  func gen<T>() -> T {} // expected-note 2 {{in call to function 'gen()'}}
+  func gen<T>() -> T {} // expected-note 2 {{in call to function 'gen()'}} expected-note 2 {{'gen()' declared here}}
 }
 
 // https://github.com/swiftlang/swift/issues/74857
@@ -28,7 +28,7 @@ func test(i: Int) {
 }
 
 extension Bool {
-  func foo<T>() -> T {}
+  func foo<T>() -> T {} // expected-note {{'foo()' declared here}}
 }
 
 let _: () -> Bool = false.foo<Int> // expected-error {{cannot explicitly specialize a generic function}}