Implement DR1330 in C++11 mode, to support libstdc++4.7 which uses it.

We have a new flavor of exception specification, EST_Uninstantiated. A function
type with this exception specification carries a pointer to a FunctionDecl, and
the exception specification for that FunctionDecl is instantiated (if needed)
and used in the place of the function type's exception specification.

When a function template declaration with a non-trivial exception specification
is instantiated, the specialization's exception specification is set to this
new 'uninstantiated' kind rather than being instantiated immediately.

Expr::CanThrow has migrated onto Sema, so it can instantiate exception specs
on-demand. Also, any odr-use of a function triggers the instantiation of its
exception specification (the exception specification could be needed by IRGen).
In passing, fix two places where a DeclRefExpr was created but the corresponding
function was not actually marked odr-used. We used to get away with this, but
don't any more.

Also fix a bug where instantiating an exception specification which refers to
function parameters resulted in a crash. We still have the same bug in default
arguments, which I'll be looking into next.

This, plus a tiny patch to fix libstdc++'s common_type, is enough for clang to
parse (and, in very limited testing, support) all of libstdc++4.7's standard
headers.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@154886 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 2 deletions

diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index e4b40e624c..af86cb2c43 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -3135,6 +3135,9 @@ static bool EvaluateUnaryTypeTrait(Sema &Self, UnaryTypeTrait UTT,
             FoundAssign = true;
             const FunctionProtoType *CPT
                 = Operator->getType()->getAs<FunctionProtoType>();
+            CPT = Self.ResolveExceptionSpec(KeyLoc, CPT);
+            if (!CPT)
+              return false;
             if (CPT->getExceptionSpecType() == EST_Delayed)
               return false;
             if (!CPT->isNothrow(Self.Context))
@@ -3174,6 +3177,9 @@ static bool EvaluateUnaryTypeTrait(Sema &Self, UnaryTypeTrait UTT,
           FoundConstructor = true;
           const FunctionProtoType *CPT
               = Constructor->getType()->getAs<FunctionProtoType>();
+          CPT = Self.ResolveExceptionSpec(KeyLoc, CPT);
+          if (!CPT)
+            return false;
           if (CPT->getExceptionSpecType() == EST_Delayed)
             return false;
           // FIXME: check whether evaluating default arguments can throw.
@@ -3209,6 +3215,9 @@ static bool EvaluateUnaryTypeTrait(Sema &Self, UnaryTypeTrait UTT,
         if (Constructor->isDefaultConstructor()) {
           const FunctionProtoType *CPT
               = Constructor->getType()->getAs<FunctionProtoType>();
+          CPT = Self.ResolveExceptionSpec(KeyLoc, CPT);
+          if (!CPT)
+            return false;
           if (CPT->getExceptionSpecType() == EST_Delayed)
             return false;
           // TODO: check whether evaluating default arguments can throw.
@@ -5203,9 +5212,9 @@ ExprResult Sema::BuildCXXMemberCallExpr(Expr *E, NamedDecl *FoundDecl,
 
 ExprResult Sema::BuildCXXNoexceptExpr(SourceLocation KeyLoc, Expr *Operand,
                                       SourceLocation RParen) {
+  CanThrowResult CanThrow = canThrow(Operand);
   return Owned(new (Context) CXXNoexceptExpr(Context.BoolTy, Operand,
-                                             Operand->CanThrow(Context),
-                                             KeyLoc, RParen));
+                                             CanThrow, KeyLoc, RParen));
 }
 
 ExprResult Sema::ActOnNoexceptExpr(SourceLocation KeyLoc, SourceLocation,