mesa: Assert that array index is not negative.

diff --git a/src/mesa/main/texcompress_fxt1.c b/src/mesa/main/texcompress_fxt1.c
index 71e40dd3e93ab35055d47dbf78ef954a6c666383..149853f7acdc4bf2dac4282d47251e973503cc1d 100644 (file)
--- a/src/mesa/main/texcompress_fxt1.c
+++ b/src/mesa/main/texcompress_fxt1.c
@@ -528,6 +528,7 @@ fxt1_lloyd (GLfloat vec[][MAX_COMP], GLint nv,
 #else
          GLint best = fxt1_bestcol(vec, nv, input[k], nc, &err);
 #endif
+         assert(best >= 0);
          /* add in closest color */
          for (i = 0; i < nc; i++) {
             sum[best][i] += input[k][i];