[Diagnostics] Simplify logic in diagnoseAmbiguityWithFixes for emitting

the ambiguity diagnostic by combining a few special errors into one.

Author: hborla

include/swift/AST/DiagnosticsSema.def

@@ -61,14 +61,8 @@ ERROR(ambiguous_member_overload_set,none,
 ERROR(ambiguous_reference_to_decl,none,
       "ambiguous reference to %0 %1", (DescriptiveDeclKind, DeclName))
 ERROR(no_overloads_match_exactly_in_call,none,
-      "no exact matches in call to %0 %1",
-      (DescriptiveDeclKind, DeclName))
-ERROR(no_overloads_match_exactly_in_call_no_labels,none,
-      "no exact matches in call to %0 %1",
-      (DescriptiveDeclKind, DeclBaseName))
-ERROR(no_overloads_match_exactly_in_call_special,none,
-      "no exact matches in call to %0",
-      (DescriptiveDeclKind))
+      "no exact matches in call to %0 %select{%2|}1",
+      (DescriptiveDeclKind, bool, DeclBaseName))
 ERROR(no_overloads_match_exactly_in_assignment,none,
       "no exact matches in assignment to %0",
       (DeclBaseName))

lib/Sema/ConstraintSystem.cpp

@@ -2824,25 +2824,11 @@ bool ConstraintSystem::diagnoseAmbiguityWithFixes(
       auto baseName = name.getBaseName();
       DE.diagnose(commonAnchor->getLoc(), diag::no_candidates_match_result_type,
                   baseName.userFacingName(), getContextualType(anchor));
-    } else if (name.isSpecial()) {
-      // If this is a special name, avoid printing it because printing the
-      // decl kind is sufficient.
-      DE.diagnose(commonAnchor->getLoc(),
-                  diag::no_overloads_match_exactly_in_call_special,
-                  decl->getDescriptiveKind());
-    } else if (llvm::all_of(ambiguousOverload->choices,
-                            [&name](const OverloadChoice &choice) {
-                              return choice.getDecl()->getFullName() == name;
-                            })) {
-      // If the labels match in each overload, print a full name.
-      DE.diagnose(commonAnchor->getLoc(),
-                  diag::no_overloads_match_exactly_in_call,
-                  decl->getDescriptiveKind(), name);
     } else {
-      // If the labels are different, we can only print a base name.
       DE.diagnose(commonAnchor->getLoc(),
-                  diag::no_overloads_match_exactly_in_call_no_labels,
-                  decl->getDescriptiveKind(), name.getBaseName());
+                  diag::no_overloads_match_exactly_in_call,
+                  decl->getDescriptiveKind(), name.isSpecial(),
+                  name.getBaseName());
     }
 
     // Produce candidate notes

test/Sema/diag_non_ephemeral.swift

@@ -489,7 +489,7 @@ func takesPointerOverload(x: Int = 0, @_nonEphemeral _ ptr: UnsafeMutablePointer
 
 func testAmbiguity() {
   var arr = [1, 2, 3]
-  takesPointerOverload(&arr) // expected-error {{no exact matches in call to global function 'takesPointerOverload(x:_:)'}}
+  takesPointerOverload(&arr) // expected-error {{no exact matches in call to global function 'takesPointerOverload'}}
 }
 
 func takesPointerOverload2(@_nonEphemeral _ ptr: UnsafePointer<Int>) {}

test/decl/ext/protocol.swift

@@ -236,9 +236,9 @@ extension P4 where Self.AssocP4 == Bool {
 }
 
 func testP4(_ s4a: S4a, s4b: S4b, s4c: S4c, s4d: S4d) {
-  s4a.extP4a() // expected-error{{no exact matches in call to instance method 'extP4a()'}}
+  s4a.extP4a() // expected-error{{no exact matches in call to instance method 'extP4a'}}
   s4b.extP4a() // ok
-  s4c.extP4a() // expected-error{{no exact matches in call to instance method 'extP4a()'}}
+  s4c.extP4a() // expected-error{{no exact matches in call to instance method 'extP4a'}}
   s4c.extP4Int() // okay
   var b1 = s4d.extP4a() // okay, "Bool" version
   b1 = true // checks type above