https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119850
Bug ID: 119850
Summary: #pragma GCC diagnostic ignored "-Wstrict-overflow" is
ignored
Product: gcc
Version: 14.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: peppe at gcc dot gnu.org
Target Milestone: ---
Wrapping a function that raises -Wstrict-overflow with #pragma GCC diagnostic
ignored does not suppress the relative warning.
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wstrict-overflow"
#include <nlohmann/json.hpp>
#pragma GCC diagnostic pop
int main()
{
using json = nlohmann::json;
json j = json::parse(R"(
{
"pi": 3.141e2,
"happy": true
}
)");
std::string s = j.dump(4);
}
On GCC 14.2, with -Wall -Wextra -Wstrict-overflow=3, this still emits a
warning:
<source>: In function 'nlohmann::json_v3_11_1::detail::dtoa_impl::cached_power
nlohmann::json_v3_11_1::detail::dtoa_impl::get_cached_power_for_binary_exponent(int)':
<source>:19:1: warning: assuming signed overflow does not occur when changing X
+- C1 cmp C2 to X cmp C2 -+ C1 [-Wstrict-overflow]
19 | }
| ^
Even if one wraps the entire file (not just the header) with the pragma, the
warning is not suppressed (!). The fact that the header is in a -isystem path
doesn't affect anything (but that seems to be by design, PR119388).
One can reduce the testcase by picking the function out of nlohmann-json). You
can find both the original and the reduction here:
https://gcc.godbolt.org/z/hTWMdjq7b
