From ce52f1f7074d96c4d9ce63b1169c11087757e926 Mon Sep 17 00:00:00 2001 From: Lewis Hyatt Date: Mon, 27 Nov 2023 12:08:41 -0500 Subject: libcpp: Fix unsigned promotion for unevaluated divide by zero [PR112701] When libcpp encounters a divide by zero while processing a constant expression "x/y", it returns "x" as a fallback. The value of the fallback is not normally important, since an error will be generated anyway, but if the expression appears in an unevaluated context, such as "0 ? 0/0u : -1", then there will be no error, and the fallback value will be meaningful to the extent that it may cause promotion from signed to unsigned of an operand encountered later. As the PR notes, libcpp does not do the unsigned promotion correctly in this case; fix it by making the fallback return value unsigned as necessary. libcpp/ChangeLog: PR preprocessor/112701 * expr.cc (num_div_op): Set unsignedp appropriately when returning a stub value for divide by 0. gcc/testsuite/ChangeLog: PR preprocessor/112701 * gcc.dg/cpp/expr.c: Add additional tests to cover divide by 0 in an unevaluated context, where the unsignedness still matters. --- libcpp/expr.cc | 1 + 1 file changed, 1 insertion(+) (limited to 'libcpp') diff --git a/libcpp/expr.cc b/libcpp/expr.cc index 825d2c2369d..4f4a9722ac7 100644 --- a/libcpp/expr.cc +++ b/libcpp/expr.cc @@ -2216,6 +2216,7 @@ num_div_op (cpp_reader *pfile, cpp_num lhs, cpp_num rhs, enum cpp_ttype op, if (!pfile->state.skip_eval) cpp_error_with_line (pfile, CPP_DL_ERROR, location, 0, "division by zero in #if"); + lhs.unsignedp = unsignedp; return lhs; } -- cgit v1.2.3