13309 Patch for clang 3.4. This will improve the backtrace for sfinae errors.

pr13309.34.patch

diff --git a/tools/clang/include/clang/Sema/TemplateDeduction.h b/tools/clang/include/clang/Sema/TemplateDeduction.h
index 1daa689..793a50a 100644
--- a/tools/clang/include/clang/Sema/TemplateDeduction.h
+++ b/tools/clang/include/clang/Sema/TemplateDeduction.h
@@ -36,6 +36,9 @@ class TemplateDeductionInfo {
   /// deduction is occurring.
   SourceLocation Loc;
 
+  /// \brief Should we suppress errors during substitution?
+  bool IsSFINAEContext;
+
   /// \brief Have we suppressed an error during deduction?
   bool HasSFINAEDiagnostic;
 
@@ -48,7 +51,8 @@ class TemplateDeductionInfo {
 
 public:
   TemplateDeductionInfo(SourceLocation Loc)
-    : Deduced(0), Loc(Loc), HasSFINAEDiagnostic(false), Expression(0) { }
+    : Deduced(0), Loc(Loc), IsSFINAEContext(true), HasSFINAEDiagnostic(false), 
+    Expression(0) { }
 
   /// \brief Returns the location at which template argument is
   /// occurring.
@@ -78,6 +82,10 @@ public:
     Deduced = NewDeduced;
   }
 
+  /// \brief Should we suppress errors during this deduction?
+  bool isSFINAEContext() const { return IsSFINAEContext; }
+  void setSFINAEContext(bool SFINAE) { IsSFINAEContext = SFINAE; }
+
   /// \brief Is a SFINAE diagnostic available?
   bool hasSFINAEDiagnostic() const {
     return HasSFINAEDiagnostic;
diff --git a/tools/clang/lib/Sema/SemaOverload.cpp b/tools/clang/lib/Sema/SemaOverload.cpp
index 802f2b7..0f627a7 100644
--- a/tools/clang/lib/Sema/SemaOverload.cpp
+++ b/tools/clang/lib/Sema/SemaOverload.cpp
@@ -10335,6 +10335,29 @@ static ExprResult FinishOverloadedCallExpr(Sema &SemaRef, Scope *S, Expr *Fn,
     if (!Recovery.isInvalid())
       return Recovery;
 
+    // Produce the diagnostics for every substitution failure
+    for(OverloadCandidateSet::iterator Cand = CandidateSet->begin();
+      Cand != CandidateSet->end();Cand++) {
+      if (Cand->DeductionFailure.Result == Sema::TDK_SubstitutionFailure) {
+        TemplateDeductionInfo Info(CandidateSet->getLocation());
+        Info.setSFINAEContext(false);
+        FunctionDecl *Specialization = 0;
+        TemplateArgumentListInfo TemplateArgStorage, *ExplicitTemplateArgs = 0;
+        if (ULE->hasExplicitTemplateArgs()) {
+          ULE->getExplicitTemplateArgs().copyInto(TemplateArgStorage);
+          ExplicitTemplateArgs = &TemplateArgStorage;
+        }
+        Sema::TemplateDeductionResult Result =
+          SemaRef.DeduceTemplateArguments(Cand->Function->getDescribedFunctionTemplate(),
+                                  ExplicitTemplateArgs,
+                                  Args,
+                                  Specialization, Info);
+        assert(Result && "template deduction didn't fail on retry");
+        if (Result)
+          continue;
+      }
+    }
+
     SemaRef.Diag(Fn->getLocStart(),
          diag::err_ovl_no_viable_function_in_call)
       << ULE->getName() << Fn->getSourceRange();
diff --git a/tools/clang/lib/Sema/SemaTemplateInstantiate.cpp b/tools/clang/lib/Sema/SemaTemplateInstantiate.cpp
index 8904f37..c280cbc 100644
--- a/tools/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/tools/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -706,7 +706,8 @@ Optional<TemplateDeductionInfo *> Sema::isSFINAEContext() const {
       // We're either substitution explicitly-specified template arguments
       // or deduced template arguments, so SFINAE applies.
       assert(Active->DeductionInfo && "Missing deduction info pointer");
-      return Active->DeductionInfo;
+      if (Active->DeductionInfo->isSFINAEContext())
+        return Active->DeductionInfo;
     }
   }