https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88674
Bug ID: 88674 Summary: GCC thinks that register is a qualifier in function declaration with no parameters. Product: gcc Version: 9.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: anders.granlund.0 at gmail dot com Target Milestone: --- Test case (prog.c): void f(register void); int main() { } Compilation command line: gcc prog.c -Wall -Wextra -std=c11 -pedantic-errors Observed behaviour: The following error message was outputed: prog.c:1:8: error: 'void' as only parameter may not be qualified 1 | void f(register void); | ^~~~~~~~~~~~~ Expected behaviour: No error message outputed. The program is valid. register is not a type qualifier. Note: Clang accepts the program without outputing any error message.