Sema: allow imaginary constants via GNU extension if UDL overloads not present.

C++14 added user-defined literal support for complex numbers so that you can
write something like "complex<double> val = 2i". However, there is an existing
GNU extension supporting this syntax and interpreting the result as a _Complex
type.

This changes parsing so that such literals are interpreted in terms of C++14's
operators if an overload is present but otherwise falls back to the original
GNU extension.

llvm-svn: 303694

1 files changed, 10 insertions, 6 deletions

diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index 678817f0299..2852ea41631 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -3066,7 +3066,7 @@ Sema::LiteralOperatorLookupResult
 Sema::LookupLiteralOperator(Scope *S, LookupResult &R,
                             ArrayRef<QualType> ArgTys,
                             bool AllowRaw, bool AllowTemplate,
-                            bool AllowStringTemplate) {
+                            bool AllowStringTemplate, bool DiagnoseMissing) {
   LookupName(R, S);
   assert(R.getResultKind() != LookupResult::Ambiguous &&
          "literal operator lookup can't be ambiguous");
@@ -3167,11 +3167,15 @@ Sema::LookupLiteralOperator(Scope *S, LookupResult &R,
     return LOLR_StringTemplate;
 
   // Didn't find anything we could use.
-  Diag(R.getNameLoc(), diag::err_ovl_no_viable_literal_operator)
-    << R.getLookupName() << (int)ArgTys.size() << ArgTys[0]
-    << (ArgTys.size() == 2 ? ArgTys[1] : QualType()) << AllowRaw
-    << (AllowTemplate || AllowStringTemplate);
-  return LOLR_Error;
+  if (DiagnoseMissing) {
+    Diag(R.getNameLoc(), diag::err_ovl_no_viable_literal_operator)
+        << R.getLookupName() << (int)ArgTys.size() << ArgTys[0]
+        << (ArgTys.size() == 2 ? ArgTys[1] : QualType()) << AllowRaw
+        << (AllowTemplate || AllowStringTemplate);
+    return LOLR_Error;
+  }
+
+  return LOLR_ErrorNoDiagnostic;
 }
 
 void ADLResult::insert(NamedDecl *New) {