[webkit-dev] Reminder: be careful when printing sized integer types

Michael Catanzaro mcatanzaro at igalia.com
Tue May 9 12:07:41 PDT 2017


This is just a reminder to avoid a case that occasionally causes 
warnings for GTK+. On Mac, uint64_t is (I assume) a typedef for 
unsigned long long. But on Linux 86_64 it's a typedef for unsigned 
long. This means they have to be printed differently. Using "%llu" to 
print a uint64_t (presumably) works on Mac, but it causes compiler 
warnings on Linux. The right way is unfortunately to use "%" PRIu64, 
which expands to "%llu" on Mac and "%lu" on Linux. There are variants 
on these macros for many different integer types: 

It's verbose, but helps us avoid warnings. And since it's declared in 
stdint.h/cstdint, if you're using uint64_t then it's already available.



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