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def66597e1
* doc/warnings.texi (warnings): -Werror is not always a bad idea; clarify that it's intended for developers, not for ordinary builds, and mention --enable-gcc-warnings as one possible use.
66 lines
2.4 KiB
Plaintext
66 lines
2.4 KiB
Plaintext
@node warnings
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@section warnings
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The @code{warnings} module allows to regularly build a package with more
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GCC warnings than the default warnings emitted by GCC.
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It provides the following functionality:
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@itemize @bullet
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@item
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You can select some warning options, such as @samp{-Wall}, to be enabled
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whenever building with a GCC version that supports these options. The
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user can choose to override these warning options by providing the
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opposite options in the @code{CFLAGS} variable at configuration time.
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@item
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You can make these warnings apply to selected directories only. In
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projects where subprojects are maintained by different people, or where
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parts of the source code are imported from external sources (for example
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from gnulib), it is useful to apply different warning options to
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different directories.
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@item
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It lets you use @samp{-Werror} at @samp{make distcheck} time, to verify
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that on the maintainer's system, no warnings remain. (Note that use of
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@samp{-Werror} in @code{CFLAGS} does not work in general, because it may
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break autoconfiguration.)
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@item
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Similarly, it lets you use @samp{-Werror} when the builder runs
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@command{configure} with an option such as
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@option{--enable-gcc-warnings}.
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@end itemize
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To use this module, you need the following:
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@enumerate
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@item
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In @file{configure.ac}, use for example
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@smallexample
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gl_WARN_ADD([-Wall], [WARN_CFLAGS])
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gl_WARN_ADD([-Wpointer-arith], [WARN_CFLAGS])
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@end smallexample
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@item
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In the directories which shall use @code{WARN_CFLAGS}, use it in the
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definition of @code{AM_CFLAGS}, like this:
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@smallexample
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AM_CFLAGS = $(WARN_CFLAGS)
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@end smallexample
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Note that the @code{AM_CFLAGS} is used in combination with @code{CFLAGS}
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and before @code{CFLAGS} in build rules emitted by Automake. This allows
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the user to provide @code{CFLAGS} that override the @code{WARN_CFLAGS}.
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@end enumerate
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@samp{gl_WARN_ADD([-Werror])} is intended for developers, and should be
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avoided in contexts where it would affect ordinary installation builds. The
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warnings emitted by GCC depend, to some extent, on the contents of the
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system header files, on the size and signedness of built-in types, etc.
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Use of @samp{-Werror} would cause frustration to all users on platforms
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that the maintainer has not tested before the release. It is better if
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@samp{-Werror} is off by default, and is enabled only by developers.
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For example, @samp{-Werror} could affect @samp{make distcheck} or
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@samp{configure --enable-gcc-warnings} as mentioned above.
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