[OpenMP] Prevent nesting of target constructs within target code execution regions.

Summary:
This patch enhances Sema to check for the following restriction:

OpenMP 4.5 [2.17 Nesting of Regions]
If a target, target update, target data, target enter data, or
target exit data construct is encountered during execution of a
target region, the behavior is unspecified.

Reviewers: ABataev

Differential Revision: http://reviews.llvm.org/D16758

llvm-svn: 259464

1 files changed, 1 insertions, 0 deletions

diff --git a/clang/test/OpenMP/target_parallel_messages.cpp b/clang/test/OpenMP/target_parallel_messages.cpp
index 65525512fab..6fc83ecdfe2 100644
--- a/clang/test/OpenMP/target_parallel_messages.cpp
+++ b/clang/test/OpenMP/target_parallel_messages.cpp
@@ -24,6 +24,7 @@ int main(int argc, char **argv) {
   #pragma omp target parallel } // expected-warning {{extra tokens at the end of '#pragma omp target parallel' are ignored}}
   foo();
   #pragma omp target parallel
+  foo();
   // expected-warning@+1 {{extra tokens at the end of '#pragma omp target parallel' are ignored}}
   #pragma omp target parallel unknown()
   foo();