[gcc(refs/vendors/ibm/heads/gcc-9)] Restore enable_if lost during original import of pstl

[Peter Bergner]

https://gcc.gnu.org/g:2f2585ed25883d415bf451743a8d22aa17d64e9c

commit 2f2585ed25883d415bf451743a8d22aa17d64e9c
Author: Thomas Rodgers <trodgers@redhat.com>
Date:   Wed Dec 11 03:38:53 2019 +0000

    Restore enable_if lost during original import of pstl
    
    	* include/pstl/glue_numeric_defs.h: Restore enable_if lost during original
    	import of pstl.
    	* include/pstl/glue_numeric_impl.h: Likewise.
    
    From-SVN: r279213

Diff:
---
 libstdc++-v3/ChangeLog                        | 10 ++++++++++
 libstdc++-v3/include/pstl/glue_numeric_defs.h |  2 +-
 libstdc++-v3/include/pstl/glue_numeric_impl.h |  2 +-
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 4a092e8..40a7116 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,13 @@
+2019-12-10  Thomas Rodgers  <trodgers@redhat.com>
+
+	Backport from mainline
+	2019-12-10  Thomas Rodgers  <trodgers@redhat.com>
+
+	* include/pstl/glue_numeric_defs.h: Restore enable_if lost during original
+	import of pstl.
+	* include/pstl/glue_numeric_impl.h: Likewise.
+
+
 2019-12-09  Jonathan Wakely  <jwakely@redhat.com>
 
 	Backport from mainline
diff --git a/libstdc++-v3/include/pstl/glue_numeric_defs.h b/libstdc++-v3/include/pstl/glue_numeric_defs.h
index 55187f1..12e967b 100644
--- a/libstdc++-v3/include/pstl/glue_numeric_defs.h
+++ b/libstdc++-v3/include/pstl/glue_numeric_defs.h
@@ -55,7 +55,7 @@ exclusive_scan(_ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIte
                _ForwardIterator2 __result, _Tp __init);
 
 template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Tp, class _BinaryOperation>
-_ForwardIterator2
+__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2>
 exclusive_scan(_ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last,
                _ForwardIterator2 __result, _Tp __init, _BinaryOperation __binary_op);
 
diff --git a/libstdc++-v3/include/pstl/glue_numeric_impl.h b/libstdc++-v3/include/pstl/glue_numeric_impl.h
index bde0b03..748f47c 100644
--- a/libstdc++-v3/include/pstl/glue_numeric_impl.h
+++ b/libstdc++-v3/include/pstl/glue_numeric_impl.h
@@ -100,7 +100,7 @@ exclusive_scan(_ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIte
 }
 
 template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Tp, class _BinaryOperation>
-_ForwardIterator2
+__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2>
 exclusive_scan(_ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last,
                _ForwardIterator2 __result, _Tp __init, _BinaryOperation __binary_op)
 {