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.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@73332 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 3 insertions, 0 deletions

diff --git a/include/clang/Basic/Diagnostic.td b/include/clang/Basic/Diagnostic.td
index 67d8eaafc9..6aa3b438ab 100644
--- a/include/clang/Basic/Diagnostic.td
+++ b/include/clang/Basic/Diagnostic.td
@@ -45,6 +45,7 @@ class Diagnostic<string text, DiagClass DC, DiagMapping defaultmapping> {
   string      Component = ?;
   string      Text = text;
   DiagClass   Class = DC;
+  bit         SFINAE = 1;
   DiagMapping DefaultMapping = defaultmapping;
   DiagGroup   Group;
 }
@@ -61,6 +62,8 @@ class DefaultWarn   { DiagMapping DefaultMapping = MAP_WARNING; }
 class DefaultError  { DiagMapping DefaultMapping = MAP_ERROR; }
 class DefaultFatal  { DiagMapping DefaultMapping = MAP_FATAL; }
 
+class NoSFINAE { bit SFINAE = 0; }
+
 // Definitions for Diagnostics.
 include "DiagnosticASTKinds.td"
 include "DiagnosticAnalysisKinds.td"