https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87310
Bug ID: 87310 Summary: -Wc90-c99-compat does not warn about bool usage Product: gcc Version: 8.1.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: kohanyi.robert at gmail dot com Target Milestone: --- Created attachment 44694 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44694&action=edit gcc -v outputs When compiling code that uses <stdbool.h> and bool declarations with -Wc90-c99-compat (with or without -std=c90), no diagnostic is issued. Something like this #include <stdio.h> #include <stdbool.h> main() { bool ok = true; printf("%u\n", ok); } when compiled with gcc -std=c90 -Wc90-c99-compat a.c there's no warning, but I expected a warn about bool usage. When it looks like this #include <stdio.h> main() { _Bool ok = 1; printf("%u\n", ok); } the warning `warning: ISO C90 does not support boolean types [-Wc90-c99-compat]' is raised. Tried with multiple version of gcc. Attached the output of different gcc -v runs. Try it here at tio.run: https://bit.ly/2CXnvXm StackOverflow thread: https://stackoverflow.com/questions/52307780