The macro 'btFullAssert' is used like this:

btFullAssert ( yadda_yadda ) ;

...in the btScalar.h header, it's defined as:

    #define btFullAssert

...which means that the statement above becomes:

    ( yadda_yadda ) ;

...which means that code may actually be compiled and executed (unnecessarily) - and even when the code is something simple like:

    ( i > 0 && i < 3 ) ;

...the GCC tosses out a 'statement with no effect' warning - before
it optimises away the code.

The fix is:

   #define btFullAssert(x)

...so that the macro still takes a parameter which is now removed
from the sources so you get:

    ;

...which is guaranteed not to generate code.

src/LinearMath/btScalar.h

@@ -39,7 +39,7 @@ subject to the following restrictions:
 		#include <assert.h>
 		#define btAssert assert
 		//btFullAssert is optional, slows down a lot
-		#define btFullAssert
+		#define btFullAssert(x)
 #else
 	
 	//non-windows systems
@@ -51,7 +51,7 @@ subject to the following restrictions:
 		#endif
 		#define btAssert assert
 		//btFullAssert is optional, slows down a lot
-		#define btFullAssert
+		#define btFullAssert(x)
 #endif
 
 /// older compilers (gcc 3.x) and Sun needs double version of sqrt etc.