From 33834516f361dfb3e52c6ca71336adaf45b1d65e Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Sun, 14 Jun 2009 07:33:30 +0000
Subject: Update LLVM.

Implement support for C++ Substitution Failure Is Not An Error
(SFINAE), which says that errors that occur during template argument
deduction do *not* produce diagnostics and do not necessarily make a
program ill-formed. Instead, template argument deduction silently
fails. This is currently implemented for template argument deduction
during matching of class template partial specializations, although
the mechanism will also apply to template argument deduction for
function templates. The scheme is simple:

  - If we are in a template argument deduction context, any diagnostic
    that is considered a SFINAE error (or warning) will be
    suppressed. The error will be propagated up the call stack via the
    normal means.
  - By default, all warnings and errors are SFINAE errors. Add the
    NoSFINAE class to a diagnostic in the .td file to make it a hard
    error (e.g., for access-control violations).

Note that, to make this fully work, every place in Sema that emits an
error *and then immediately recovers* will need to check
Sema::isSFINAEContext() to determine whether it must immediately
return an error rather than recovering.

llvm-svn: 73332
---
 clang/lib/Basic/Diagnostic.cpp | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

(limited to 'clang/lib/Basic/Diagnostic.cpp')

diff --git a/clang/lib/Basic/Diagnostic.cpp b/clang/lib/Basic/Diagnostic.cpp
index 3b3d61b08d0..323f7a7d4af 100644
--- a/clang/lib/Basic/Diagnostic.cpp
+++ b/clang/lib/Basic/Diagnostic.cpp
@@ -46,6 +46,7 @@ struct StaticDiagInfoRec {
   unsigned short DiagID;
   unsigned Mapping : 3;
   unsigned Class : 3;
+  bool SFINAE : 1;
   const char *Description;
   const char *OptionGroup;
   
@@ -58,8 +59,8 @@ struct StaticDiagInfoRec {
 };
 
 static const StaticDiagInfoRec StaticDiagInfo[] = {
-#define DIAG(ENUM,CLASS,DEFAULT_MAPPING,DESC,GROUP) \
-  { diag::ENUM, DEFAULT_MAPPING, CLASS, DESC, GROUP },
+#define DIAG(ENUM,CLASS,DEFAULT_MAPPING,DESC,GROUP,SFINAE)    \
+  { diag::ENUM, DEFAULT_MAPPING, CLASS, SFINAE, DESC, GROUP },
 #include "clang/Basic/DiagnosticCommonKinds.inc"
 #include "clang/Basic/DiagnosticDriverKinds.inc"
 #include "clang/Basic/DiagnosticFrontendKinds.inc"
@@ -68,7 +69,7 @@ static const StaticDiagInfoRec StaticDiagInfo[] = {
 #include "clang/Basic/DiagnosticASTKinds.inc"
 #include "clang/Basic/DiagnosticSemaKinds.inc"
 #include "clang/Basic/DiagnosticAnalysisKinds.inc"
-{ 0, 0, 0, 0, 0 }
+  { 0, 0, 0, 0, 0, 0}
 };
 #undef DIAG
 
@@ -89,7 +90,7 @@ static const StaticDiagInfoRec *GetDiagInfo(unsigned DiagID) {
 #endif
   
   // Search the diagnostic table with a binary search.
-  StaticDiagInfoRec Find = { DiagID, 0, 0, 0, 0 };
+  StaticDiagInfoRec Find = { DiagID, 0, 0, 0, 0, 0 };
   
   const StaticDiagInfoRec *Found =
     std::lower_bound(StaticDiagInfo, StaticDiagInfo + NumDiagEntries, Find);
@@ -115,6 +116,12 @@ const char *Diagnostic::getWarningOptionForDiag(unsigned DiagID) {
   return 0;
 }
 
+bool Diagnostic::isBuiltinSFINAEDiag(unsigned DiagID) {
+  if (const StaticDiagInfoRec *Info = GetDiagInfo(DiagID))
+    return Info->SFINAE && Info->Class != CLASS_NOTE;
+  return false;
+}
+
 /// getDiagClass - Return the class field of the diagnostic.
 ///
 static unsigned getBuiltinDiagClass(unsigned DiagID) {
@@ -399,7 +406,7 @@ bool Diagnostic::setDiagnosticGroupMapping(const char *Group,
 
 /// ProcessDiag - This is the method used to report a diagnostic that is
 /// finally fully formed.
-void Diagnostic::ProcessDiag() {
+bool Diagnostic::ProcessDiag() {
   DiagnosticInfo Info(this);
     
   // Figure out the diagnostic level of this message.
@@ -449,13 +456,13 @@ void Diagnostic::ProcessDiag() {
   // If a fatal error has already been emitted, silence all subsequent
   // diagnostics.
   if (FatalErrorOccurred)
-    return;
+    return false;
 
   // If the client doesn't care about this message, don't issue it.  If this is
   // a note and the last real diagnostic was ignored, ignore it too.
   if (DiagLevel == Diagnostic::Ignored ||
       (DiagLevel == Diagnostic::Note && LastDiagLevel == Diagnostic::Ignored))
-    return;
+    return false;
 
   // If this diagnostic is in a system header and is not a clang error, suppress
   // it.
@@ -464,7 +471,7 @@ void Diagnostic::ProcessDiag() {
       Info.getLocation().getSpellingLoc().isInSystemHeader() &&
       (DiagLevel != Diagnostic::Note || LastDiagLevel == Diagnostic::Ignored)) {
     LastDiagLevel = Diagnostic::Ignored;
-    return;
+    return false;
   }
 
   if (DiagLevel >= Diagnostic::Error) {
@@ -477,6 +484,8 @@ void Diagnostic::ProcessDiag() {
   if (Client->IncludeInDiagnosticCounts()) ++NumDiagnostics;
 
   CurDiagID = ~0U;
+
+  return true;
 }
 
 
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