Add tracking for extension based warnings

Using '#extension foo: warn' instructs the compiler to generate a
warning when some feature of the extension 'foo' is used.  This patch
adds some infrastructure needed to support that for variables.

Similar changes will be needed for types and built-in functions.

1 files changed, 5 insertions, 0 deletions

diff --git a/ir.h b/ir.h
index fee23b2582..13d07155a4 100644
--- a/ir.h
+++ b/ir.h
@@ -157,6 +157,11 @@ public:
    unsigned array_lvalue:1;
 
    /**
+    * Emit a warning if this variable is accessed.
+    */
+   const char *warn_extension;
+
+   /**
     * Value assigned in the initializer of a variable declared "const"
     */
    ir_constant *constant_value;