[Sema] Clean up -Wc++11-narrowing-const-reference code after #76094. NFC (#77278)

Author: MaskRay

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -6160,23 +6160,19 @@ def err_illegal_initializer_type : Error<"illegal initializer type %0">;
 def ext_init_list_type_narrowing : ExtWarn<
   "type %0 cannot be narrowed to %1 in initializer list">,
   InGroup<CXX11Narrowing>, DefaultError, SFINAEFailure;
-// *_narrowing_const_reference diagnostics have the same messages, but are
-// controlled by -Wc++11-narrowing-const-reference for narrowing involving a
-// const reference.
 def ext_init_list_type_narrowing_const_reference : ExtWarn<
-  "type %0 cannot be narrowed to %1 in initializer list">,
+  ext_init_list_type_narrowing.Summary>,
   InGroup<CXX11NarrowingConstReference>, DefaultError, SFINAEFailure;
 def ext_init_list_variable_narrowing : ExtWarn<
   "non-constant-expression cannot be narrowed from type %0 to %1 in "
   "initializer list">, InGroup<CXX11Narrowing>, DefaultError, SFINAEFailure;
 def ext_init_list_variable_narrowing_const_reference : ExtWarn<
-  "non-constant-expression cannot be narrowed from type %0 to %1 in "
-  "initializer list">, InGroup<CXX11NarrowingConstReference>, DefaultError, SFINAEFailure;
+  ext_init_list_variable_narrowing.Summary>, InGroup<CXX11NarrowingConstReference>, DefaultError, SFINAEFailure;
 def ext_init_list_constant_narrowing : ExtWarn<
   "constant expression evaluates to %0 which cannot be narrowed to type %1">,
   InGroup<CXX11Narrowing>, DefaultError, SFINAEFailure;
 def ext_init_list_constant_narrowing_const_reference : ExtWarn<
-  "constant expression evaluates to %0 which cannot be narrowed to type %1">,
+  ext_init_list_constant_narrowing.Summary>,
   InGroup<CXX11NarrowingConstReference>, DefaultError, SFINAEFailure;
 def warn_init_list_type_narrowing : Warning<
   "type %0 cannot be narrowed to %1 in initializer list in C++11">,

clang/lib/Sema/SemaInit.cpp

@@ -10377,11 +10377,6 @@ void InitializationSequence::dump() const {
   dump(llvm::errs());
 }
 
-static bool NarrowingErrs(const LangOptions &L) {
-  return L.CPlusPlus11 &&
-         (!L.MicrosoftExt || L.isCompatibleWithMSVC(LangOptions::MSVC2015));
-}
-
 static void DiagnoseNarrowingInInitList(Sema &S,
                                         const ImplicitConversionSequence &ICS,
                                         QualType PreNarrowingType,
@@ -10402,6 +10397,19 @@ static void DiagnoseNarrowingInInitList(Sema &S,
     return;
   }
 
+  auto MakeDiag = [&](bool IsConstRef, unsigned DefaultDiagID,
+                      unsigned ConstRefDiagID, unsigned WarnDiagID) {
+    unsigned DiagID;
+    auto &L = S.getLangOpts();
+    if (L.CPlusPlus11 &&
+        (!L.MicrosoftExt || L.isCompatibleWithMSVC(LangOptions::MSVC2015)))
+      DiagID = IsConstRef ? ConstRefDiagID : DefaultDiagID;
+    else
+      DiagID = WarnDiagID;
+    return S.Diag(PostInit->getBeginLoc(), DiagID)
+           << PostInit->getSourceRange();
+  };
+
   // C++11 [dcl.init.list]p7: Check whether this is a narrowing conversion.
   APValue ConstantValue;
   QualType ConstantType;
@@ -10417,43 +10425,31 @@ static void DiagnoseNarrowingInInitList(Sema &S,
     // narrowing conversion even if the value is a constant and can be
     // represented exactly as an integer.
     QualType T = EntityType.getNonReferenceType();
-    S.Diag(PostInit->getBeginLoc(),
-           NarrowingErrs(S.getLangOpts())
-               ? (T == EntityType
-                      ? diag::ext_init_list_type_narrowing
-                      : diag::ext_init_list_type_narrowing_const_reference)
-               : diag::warn_init_list_type_narrowing)
-        << PostInit->getSourceRange()
+    MakeDiag(T != EntityType, diag::ext_init_list_type_narrowing,
+             diag::ext_init_list_type_narrowing_const_reference,
+             diag::warn_init_list_type_narrowing)
         << PreNarrowingType.getLocalUnqualifiedType()
         << T.getLocalUnqualifiedType();
     break;
   }
 
   case NK_Constant_Narrowing: {
     // A constant value was narrowed.
-    QualType T = EntityType.getNonReferenceType();
-    S.Diag(PostInit->getBeginLoc(),
-           NarrowingErrs(S.getLangOpts())
-               ? (T == EntityType
-                      ? diag::ext_init_list_constant_narrowing
-                      : diag::ext_init_list_constant_narrowing_const_reference)
-               : diag::warn_init_list_constant_narrowing)
-        << PostInit->getSourceRange()
+    MakeDiag(EntityType.getNonReferenceType() != EntityType,
+             diag::ext_init_list_constant_narrowing,
+             diag::ext_init_list_constant_narrowing_const_reference,
+             diag::warn_init_list_constant_narrowing)
         << ConstantValue.getAsString(S.getASTContext(), ConstantType)
         << EntityType.getNonReferenceType().getLocalUnqualifiedType();
     break;
   }
 
   case NK_Variable_Narrowing: {
     // A variable's value may have been narrowed.
-    QualType T = EntityType.getNonReferenceType();
-    S.Diag(PostInit->getBeginLoc(),
-           NarrowingErrs(S.getLangOpts())
-               ? (T == EntityType
-                      ? diag::ext_init_list_variable_narrowing
-                      : diag::ext_init_list_variable_narrowing_const_reference)
-               : diag::warn_init_list_variable_narrowing)
-        << PostInit->getSourceRange()
+    MakeDiag(EntityType.getNonReferenceType() != EntityType,
+             diag::ext_init_list_variable_narrowing,
+             diag::ext_init_list_variable_narrowing_const_reference,
+             diag::warn_init_list_variable_narrowing)
         << PreNarrowingType.getLocalUnqualifiedType()
         << EntityType.getNonReferenceType().getLocalUnqualifiedType();
     break;