clang's -Wmissing-prototypes option identifies global functions that can be made static (because they're only called from one compilation unit) or removed (if they're never called). The .cpp files defining these functions did not include the headers with the corresponding function prototypes used by other compilation units. Including a header file in its corresponding .cpp file can help catch mismatched declarations and definitions.
xpcom/components/nsCategoryManager.cpp:637:6 [-Wmissing-prototypes] no previous prototype for function 'NS_CreateServicesFromCategory'
xpcom/io/nsPipe3.cpp:1824:10 [-Wmissing-prototypes] no previous prototype for function 'nsPipeConstructor'
xpcom/io/nsStringStream.cpp:475:10 [-Wmissing-prototypes] no previous prototype for function 'nsStringInputStreamConstructor'
xpcom/threads/ThreadDelay.cpp:18:6 [-Wmissing-prototypes] no previous prototype for function 'DelayForChaosMode'
Differential Revision: https://phabricator.services.mozilla.com/D23265
Chris Peterson