Mesa (master): glcpp: Generate an error for division by zero

[Ian Romanick]

Module: Mesa
Branch: master
Commit: 9ca5300b6e781150cec903c73cf5fd8e1deee2f1
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=9ca5300b6e781150cec903c73cf5fd8e1deee2f1

Author: Ian Romanick <ian.d.romanick at intel.com>
Date:   Mon Jan 10 13:33:07 2011 -0800

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.

---

 src/glsl/glcpp/glcpp-parse.y |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/src/glsl/glcpp/glcpp-parse.y b/src/glsl/glcpp/glcpp-parse.y
index 148b0ff..e71c0e8 100644
--- 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;