Implement __builtin_LINE() et. al. to support source location capture.

Summary:
This patch implements the source location builtins `__builtin_LINE(), `__builtin_FUNCTION()`, `__builtin_FILE()` and `__builtin_COLUMN()`. These builtins are needed to implement [`std::experimental::source_location`](https://rawgit.com/cplusplus/fundamentals-ts/v2/main.html#reflection.src_loc.creation).

With the exception of `__builtin_COLUMN`, GCC also implements these builtins, and Clangs behavior is intended to match as closely as possible. 

Reviewers: rsmith, joerg, aaron.ballman, bogner, majnemer, shafik, martong

Reviewed By: rsmith

Subscribers: rnkovacs, loskutov, riccibruno, mgorny, kunitoki, alexr, majnemer, hfinkel, cfe-commits

Differential Revision: https://reviews.llvm.org/D37035

llvm-svn: 360937

1 files changed, 8 insertions, 4 deletions

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 5641d54383f..5b576555146 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -1315,11 +1315,15 @@ LValue CodeGenFunction::EmitLValue(const Expr *E) {
     return LV;
   }
 
-  case Expr::CXXDefaultArgExprClass:
-    return EmitLValue(cast<CXXDefaultArgExpr>(E)->getExpr());
+  case Expr::CXXDefaultArgExprClass: {
+    auto *DAE = cast<CXXDefaultArgExpr>(E);
+    CXXDefaultArgExprScope Scope(*this, DAE);
+    return EmitLValue(DAE->getExpr());
+  }
   case Expr::CXXDefaultInitExprClass: {
-    CXXDefaultInitExprScope Scope(*this);
-    return EmitLValue(cast<CXXDefaultInitExpr>(E)->getExpr());
+    auto *DIE = cast<CXXDefaultInitExpr>(E);
+    CXXDefaultInitExprScope Scope(*this, DIE);
+    return EmitLValue(DIE->getExpr());
   }
   case Expr::CXXTypeidExprClass:
     return EmitCXXTypeidLValue(cast<CXXTypeidExpr>(E));