Introduce support for emitting diagnostics (warnings + their notes)

that are suppressed during template argument deduction. This change
queues diagnostics computed during template argument deduction. Then,
if the resulting function template specialization or partial
specialization is chosen by overload resolution or partial ordering
(respectively), we will emit the queued diagnostics at that point. 

This addresses most of PR6784. However, the check for unnamed/local
template arguments (which existed before this change) is still only
skin-deep, and needs to be extended to look deeper into types. It must
be improved to finish PR6784.

llvm-svn: 116373

1 files changed, 18 insertions, 4 deletions

diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
index ce3748b901a..ae9052b704a 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -1127,7 +1127,7 @@ Sema::DeduceTemplateArguments(ClassTemplatePartialSpecializationDecl *Partial,
     return Result;
 
   InstantiatingTemplate Inst(*this, Partial->getLocation(), Partial,
-                             Deduced.data(), Deduced.size());
+                             Deduced.data(), Deduced.size(), Info);
   if (Inst)
     return TDK_InstantiationDepth;
 
@@ -1214,7 +1214,8 @@ Sema::SubstituteExplicitTemplateArguments(
   // and then substitute them into the function parameter types.
   InstantiatingTemplate Inst(*this, FunctionTemplate->getLocation(),
                              FunctionTemplate, Deduced.data(), Deduced.size(),
-           ActiveTemplateInstantiation::ExplicitTemplateArgumentSubstitution);
+           ActiveTemplateInstantiation::ExplicitTemplateArgumentSubstitution,
+                             Info);
   if (Inst)
     return TDK_InstantiationDepth;
 
@@ -1374,7 +1375,8 @@ Sema::FinishTemplateArgumentDeduction(FunctionTemplateDecl *FunctionTemplate,
   // actual function declaration.
   InstantiatingTemplate Inst(*this, FunctionTemplate->getLocation(),
                              FunctionTemplate, Deduced.data(), Deduced.size(),
-              ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution);
+              ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution,
+                             Info);
   if (Inst)
     return TDK_InstantiationDepth;
 
@@ -1429,7 +1431,7 @@ Sema::FinishTemplateArgumentDeduction(FunctionTemplateDecl *FunctionTemplate,
       TemplateArgumentLoc Arg = getTrivialTemplateArgumentLoc(*this,
                                                               Deduced[I],
                                                               NTTPType,
-                                                           SourceLocation());
+                                                            Info.getLocation());
 
       // Check the template argument, converting it as necessary.
       if (CheckTemplateArgument(Param, Arg,
@@ -1515,6 +1517,18 @@ Sema::FinishTemplateArgumentDeduction(FunctionTemplateDecl *FunctionTemplate,
     return TDK_SubstitutionFailure;
   }
 
+  // If we suppressed any diagnostics while performing template argument
+  // deduction, and if we haven't already instantiated this declaration,
+  // keep track of these diagnostics. They'll be emitted if this specialization
+  // is actually used.
+  if (Info.diag_begin() != Info.diag_end()) {
+    llvm::DenseMap<Decl *, llvm::SmallVector<PartialDiagnosticAt, 1> >::iterator
+      Pos = SuppressedDiagnostics.find(Specialization->getCanonicalDecl());
+    if (Pos == SuppressedDiagnostics.end())
+        SuppressedDiagnostics[Specialization->getCanonicalDecl()]
+          .append(Info.diag_begin(), Info.diag_end());
+  }                                                               
+
   return TDK_Success;
 }