[commit: ghc] ghc-8.6: includes: Allow headers to be built with C++11 compilers (b539a99)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : ghc-8.6
Link       : http://ghc.haskell.org/trac/ghc/changeset/b539a99cd0d53706092bcbab371bb3af74ba652d/ghc

>---------------------------------------------------------------

commit b539a99cd0d53706092bcbab371bb3af74ba652d
Author: Ben Gamari <bgamari.foss at gmail.com>
Date:   Sun Oct 28 12:24:06 2018 -0400

    includes: Allow headers to be built with C++11 compilers
    
    Summary:
    Fixes #14784. Note that C++11 is quite conservative; we could likely accept
    C++03 as well.
    
    Test Plan:
    ```
    $ cat >hi.c <<EOF
    #include <Rts.h>
    EOF
    $ g++ -std=c++11 hi.c
    ```
    
    Reviewers: simonmar, hvr
    
    Subscribers: rwbarton, carter
    
    GHC Trac Issues: #14784
    
    Differential Revision: https://phabricator.haskell.org/D5244
    
    (cherry picked from commit d3a1022fabb0ad337003fac774c6929f402ecb8b)


>---------------------------------------------------------------

b539a99cd0d53706092bcbab371bb3af74ba652d
 includes/Stg.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/includes/Stg.h b/includes/Stg.h
index 2e02347..31b2c45 100644
--- a/includes/Stg.h
+++ b/includes/Stg.h
@@ -25,8 +25,8 @@
 
 #pragma once
 
-#if !(__STDC_VERSION__ >= 199901L)
-# error __STDC_VERSION__ does not advertise C99 or later
+#if !(__STDC_VERSION__ >= 199901L) && !(__cplusplus >= 201103L)
+# error __STDC_VERSION__ does not advertise C99, C++11 or later
 #endif
 
 /*