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, 18 insertions, 0 deletions

diff --git a/test/CodeGenCXX/cxx11-exception-spec.cpp b/test/CodeGenCXX/cxx11-exception-spec.cpp
new file mode 100644
index 0000000000..461af78eae
--- /dev/null
+++ b/test/CodeGenCXX/cxx11-exception-spec.cpp
@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 -std=c++11 -verify -emit-llvm %s -o - | FileCheck %s
+
+template<typename T> void f() noexcept(sizeof(T) == 4);
+
+void g() {
+  // CHECK: declare void @_Z1fIiEvv() nounwind
+  f<int>();
+  // CHECK: declare void @_Z1fIA2_iEvv()
+  f<int[2]>();
+  // CHECK: declare void @_Z1fIfEvv() nounwind
+  void (*f1)() = &f<float>;
+  // CHECK: declare void @_Z1fIdEvv()
+  void (*f2)() = &f<double>;
+  // CHECK: declare void @_Z1fIA4_cEvv() nounwind
+  (void)&f<char[4]>;
+  // CHECK: declare void @_Z1fIcEvv()
+  (void)&f<char>;
+}