glcpp: Generate an error for division by zero

When GCC encounters a division by zero in a preprocessor directive, it
generates an error.  Since the GLSL spec says that the GLSL
preprocessor behaves like the C preprocessor, we should generate that
same error.

It's worth noting that I cannot find any text in the C99 spec that
says this should be an error.  The only text that I can find is line 5
on page 82 (section 6.5.5 Multiplicative Opertors), which says,

    "The result of the / operator is the quotient from the division of
    the first operand by the second; the result of the % operator is
    the remainder. In both operations, if the value of the second
    operand is zero, the behavior is undefined."

Fixes 093-divide-by-zero.c test and bugzilla #32831.

NOTE: This is a candidate for the 7.9 and 7.10 branches.

diff --git a/src/glsl/glcpp/glcpp-parse.y b/src/glsl/glcpp/glcpp-parse.y
index 148b0ff..e71c0e8 100644 (file)
--- a/src/glsl/glcpp/glcpp-parse.y
+++ b/src/glsl/glcpp/glcpp-parse.y
@@ -398,7 +398,12 @@ expression:
                $$ = $1 % $3;
        }
 |      expression '/' expression {
-               $$ = $1 / $3;
+               if ($3 == 0) {
+                       yyerror (& @1, parser,
+                                "division by 0 in preprocessor directive");
+               } else {
+                       $$ = $1 / $3;
+               }
        }
 |      expression '*' expression {
                $$ = $1 * $3;