r335082 - clang-cl: Emit narrowing diag for initializer lists if -fmsc-version is at least 1900 (i.e. MSVC2015).

[Nico Weber via cfe-commits]

Author: nico
Date: Tue Jun 19 16:19:34 2018
New Revision: 335082

URL: http://llvm.org/viewvc/llvm-project?rev=335082&view=rev
Log:
clang-cl: Emit narrowing diag for initializer lists if -fmsc-version is at least 1900 (i.e. MSVC2015).

Diagnostics for narrowing conversions in initializer lists are currently
DefaultIgnored in Microsoft mode. But MSVC 2015 did add warnings about
narrowing conversions (C2397), so clang-cl can remove its special case code if
MSCompatibilityVersion is new enough.

(In MSVC, C2397 is just a warning and in clang it's default-mapped to an error,
but it can be remapped, and disabled with -Wno-c++11-narrowing, so that should
be fine.)

Fixes PR37314.
https://reviews.llvm.org/D48296

Added:
    cfe/trunk/test/SemaCXX/ms-initlist-narrowing.cpp
Modified:
    cfe/trunk/lib/Sema/SemaInit.cpp

Modified: cfe/trunk/lib/Sema/SemaInit.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaInit.cpp?rev=335082&r1=335081&r2=335082&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaInit.cpp (original)
+++ cfe/trunk/lib/Sema/SemaInit.cpp Tue Jun 19 16:19:34 2018
@@ -8331,6 +8331,11 @@ void InitializationSequence::dump() cons
   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,
@@ -8364,35 +8369,34 @@ static void DiagnoseNarrowingInInitList(
     // This was a floating-to-integer conversion, which is always considered a
     // narrowing conversion even if the value is a constant and can be
     // represented exactly as an integer.
-    S.Diag(PostInit->getLocStart(),
-           (S.getLangOpts().MicrosoftExt || !S.getLangOpts().CPlusPlus11)
-               ? diag::warn_init_list_type_narrowing
-               : diag::ext_init_list_type_narrowing)
-      << PostInit->getSourceRange()
-      << PreNarrowingType.getLocalUnqualifiedType()
-      << EntityType.getLocalUnqualifiedType();
+    S.Diag(PostInit->getLocStart(), NarrowingErrs(S.getLangOpts())
+                                        ? diag::ext_init_list_type_narrowing
+                                        : diag::warn_init_list_type_narrowing)
+        << PostInit->getSourceRange()
+        << PreNarrowingType.getLocalUnqualifiedType()
+        << EntityType.getLocalUnqualifiedType();
     break;
 
   case NK_Constant_Narrowing:
     // A constant value was narrowed.
     S.Diag(PostInit->getLocStart(),
-           (S.getLangOpts().MicrosoftExt || !S.getLangOpts().CPlusPlus11)
-               ? diag::warn_init_list_constant_narrowing
-               : diag::ext_init_list_constant_narrowing)
-      << PostInit->getSourceRange()
-      << ConstantValue.getAsString(S.getASTContext(), ConstantType)
-      << EntityType.getLocalUnqualifiedType();
+           NarrowingErrs(S.getLangOpts())
+               ? diag::ext_init_list_constant_narrowing
+               : diag::warn_init_list_constant_narrowing)
+        << PostInit->getSourceRange()
+        << ConstantValue.getAsString(S.getASTContext(), ConstantType)
+        << EntityType.getLocalUnqualifiedType();
     break;
 
   case NK_Variable_Narrowing:
     // A variable's value may have been narrowed.
     S.Diag(PostInit->getLocStart(),
-           (S.getLangOpts().MicrosoftExt || !S.getLangOpts().CPlusPlus11)
-               ? diag::warn_init_list_variable_narrowing
-               : diag::ext_init_list_variable_narrowing)
-      << PostInit->getSourceRange()
-      << PreNarrowingType.getLocalUnqualifiedType()
-      << EntityType.getLocalUnqualifiedType();
+           NarrowingErrs(S.getLangOpts())
+               ? diag::ext_init_list_variable_narrowing
+               : diag::warn_init_list_variable_narrowing)
+        << PostInit->getSourceRange()
+        << PreNarrowingType.getLocalUnqualifiedType()
+        << EntityType.getLocalUnqualifiedType();
     break;
   }
 

Added: cfe/trunk/test/SemaCXX/ms-initlist-narrowing.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/ms-initlist-narrowing.cpp?rev=335082&view=auto
==============================================================================
--- cfe/trunk/test/SemaCXX/ms-initlist-narrowing.cpp (added)
+++ cfe/trunk/test/SemaCXX/ms-initlist-narrowing.cpp Tue Jun 19 16:19:34 2018
@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 %s -fsyntax-only -verify -fms-extensions -fms-compatibility-version=19.0 -std=c++11
+
+int ai[] = { 1, 2.0 };  // expected-error {{type 'double' cannot be narrowed to 'int' in initializer list}} expected-note {{silence}}
+
+template<typename T>
+struct Agg {
+  T t;
+};
+
+void f(int i) {
+  // Constant expression.
+  Agg<float> f8 = {1E50};  // expected-error {{constant expression evaluates to 1.000000e+50 which cannot be narrowed to type 'float'}} expected-note {{silence}}
+
+  // Non-constant expression.
+  double d = 1.0;
+  Agg<float> f2 = {d};  // expected-error {{non-constant-expression cannot be narrowed from type 'double' to 'float'}} expected-note {{silence}}
+}