On Fri, 20 May 2016, Andrew Haley wrote: > Given this, I do not understand why GCC does not treat implicit int as > a hard error.
Because in C the existing practice has been that we support the union of all features and extensions that can sensibly be supported with the given language version (these are warnings (pedwarns) by default in C99 mode, not restricted to -pedantic). It's possible that C code used in practice has changed sufficiently over the years that continuing to build legacy code using these features (while using default compiler options, which now imply -std=gnu11) is less of a concern; information about how many warnings for implicit int and implicit function declarations there are in distribution builds would be useful. C++ has various standard-required-diagnostics as permerrors (error by default, warning with -fpermissive). That might be a plausible model for C as well (there are plenty of always-on pedwarns, some of which could be considered for making into permerrors), though in the present case we already have more specific options for these diagnostics. -- Joseph S. Myers jos...@codesourcery.com