Commit 9953d9f04b37694e9cd78cd98869e046d4e9810f
2025-03-10T21:58:05
xkbcomp/ast-build: fix possible UB in expr AST node allocations (#659) The expression AST constructors all return `ExprDef *`. `ExprDef` is a union of all expr types. As a memory optimization, instead of allocating `sizeof(ExprDef)`, we only allocate the size of the actual type (e.g. `sizeof(ExprBinary)`) which is sometimes smaller than `sizeof(ExprDef)`. This is probably undefined behavior, and gcc (with optimization turned on) complains about it, for example: src/xkbcomp/ast-build.c:69:23: warning: array subscript ‘ExprDef[0]’ is partly outside array bounds of ‘unsigned char[24]’ [-Warray-bounds=] Since it doesn't save that much memory, drop this optimization. Fix #292. Signed-off-by: Ran Benita <ran@unusedvar.com>