Mesa (master): scons: Define YY_USE_CONST on MSVC.

[Jose Fonseca]

Module: Mesa
Branch: master
Commit: 015e8b6384bbdba8421c5dafd4783dba4d3a9182
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=015e8b6384bbdba8421c5dafd4783dba4d3a9182

Author: Jose Fonseca <jfonseca at vmware.com>
Date:   Thu Mar 19 11:53:36 2015 +0000

scons: Define YY_USE_CONST on MSVC.

This prevents the MSVC from

  warning C4090: 'function' : different 'const' qualifiers

when compiling flex generated lexers.

Reviewed-by: Brian Paul <brianp at vmware.com>

---

 scons/gallium.py |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/scons/gallium.py b/scons/gallium.py
index 2b11526..9924f1e 100755
--- a/scons/gallium.py
+++ b/scons/gallium.py
@@ -622,6 +622,14 @@ def generate(env):
 
     # Load tools
     env.Tool('lex')
+    if env['msvc']:
+        env.Append(LEXFLAGS = [
+            # Force flex to use const keyword in prototypes, as relies on
+            # __cplusplus or __STDC__ macro to determine whether it's safe to
+            # use const keyword, but MSVC never defines __STDC__ unless we
+            # disable all MSVC extensions.
+            '-DYY_USE_CONST=',
+        ])
     env.Tool('yacc')
     if env['llvm']:
         env.Tool('llvm')