cmd/cc: fix undefined behaviour warning in bv.c

Fixes warning

# _/home/dfc/go/misc/cgo/test/backdoor
/home/dfc/go/src/cmd/cc/bv.c:43:11: runtime error: left shift of 1 by 31 places cannot be represented in type 'int'

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/136330043

diff --git a/src/cmd/cc/bv.c b/src/cmd/cc/bv.c
index 51b7f4076fc39022da7deb1f35937a2eae60a4f2..db433de6a7d0aa4306eaff21a5cf2f53a24dfee1 100644 (file)
--- a/src/cmd/cc/bv.c
+++ b/src/cmd/cc/bv.c
@@ -40,6 +40,6 @@ bvset(Bvec *bv, int32 i)
 
        if(i < 0 || i >= bv->n)
                fatal(Z, "bvset: index %d is out of bounds with length %d\n", i, bv->n);
-       mask = 1 << (i % WORDBITS);
+       mask = 1UL << (i % WORDBITS);
        bv->b[i / WORDBITS] |= mask;
 }