manywarnings

[Simon Josefsson]

Bruno Haible <address@hidden> writes:

> Karl Berry wrote:
>> Wow, that is a great list.  A lot of it does not seem gettext-specific?
>
> Yes, probably 80% of that list can also be disabled on other C packages.

However, I've found some of the warnings Bruno listed useful (e.g.,
-Wredundant-decls) so I think keeping the exclusions minimal for each
project can be useful.

One side-effect of this effort could be a recommendation of a small set
of relatively uncontroversial warnings that we can recommend to people
that don't want to spend time customizing the warning list for their own
project.  We can start with -Wall and add/remove as appropriate,
assuming there is consensus that adding -Wall is a safe recommendation.

>> Maybe it would be worth putting the description of all these warnings
>> you have researched into the manual?
>
> Before doing that, I'd like to see the results that Simon, Jim, Eric, and
> others get on reasonably large code bases. My list of warnings to avoid
> is certainly biased. What we document in the manual should not be biased.

An unbiased list will be difficult to achieve, this is a subjective
area.  We could describe typical situations where each flag is useful
and where it is not useful, and let the reader decide.

There is a short list of warnings I don't see anyone ever wanting though
(e.g., -Wsystem-headers), unless for _very_ special projects.

Btw, I just reviewed the list for a few projects of mine.  Here are my
results.  Warnings in nw are excluded from the gl_MANYWARN_ALL_GCC list,
flags in gl_WARN_ADD were added to work around other warnings.

GNU Libidn:

nw="$nw -Wsystem-headers"         # Don't let system headers trigger warnings
nw="$nw -Wc++-compat"             # We don't care strongly about C++ compilers
nw="$nw -Woverlength-strings"     # Some of our strings are too large
nw="$nw -Wsign-conversion"        # Too many warnings for now
nw="$nw -Wconversion"             # Too many warnings for now
nw="$nw -Wtraditional"            # Warns on #elif which we use often
nw="$nw -Wtraditional-conversion" # Too many warnings for now
nw="$nw -Wmissing-noreturn"       # Too many warnings for now
nw="$nw -Wunreachable-code"       # Too many false positives
nw="$nw -Wlogical-op"             # Too many false positives
...
gl_WARN_ADD([-Wno-missing-field-initializers])

GNU SASL:

nw="$nw -Wsystem-headers"         # Don't let system headers trigger warnings
nw="$nw -Wpadded"                 # Our structs are not padded
nw="$nw -Wundef"                  # warns on '#if GNULIB_FOO' etc in gnulib
nw="$nw -Wc++-compat"             # We don't care strongly about C++ compilers
nw="$nw -Wswitch-enum"            # Too many warnings for now
nw="$nw -Wconversion"             # Too many warnings for now
nw="$nw -Wsign-conversion"        # Too many warnings for now
nw="$nw -Wtraditional"            # Warns on #elif which we use often
nw="$nw -Wtraditional-conversion" # Too many warnings for now
nw="$nw -Wunreachable-code"       # Too many false positives
...
gl_WARN_ADD([-Wno-missing-field-initializers])
gl_WARN_ADD([-Wno-unused-parameter])
gl_WARN_ADD([-Wno-sign-compare])
gl_WARN_ADD([-Wno-deprecated-declarations])

GnuTLS:

nw="$nw -Wsystem-headers"         # Don't let system headers trigger warnings
nw="$nw -Wc++-compat"             # We don't care about C++ compilers
nw="$nw -Wundef"                  # Warns on '#if GNULIB_FOO' etc in gnulib
nw="$nw -Wtraditional"            # Warns on #elif which we use often
nw="$nw -Wlogical-op"             # Too many false positives
nw="$nw -Wold-style-definition"   # 
nw="$nw -Wpadded"                 # Our structs are not padded
nw="$nw -Wunreachable-code"       # Too many false positives
nw="$nw -Wtraditional-conversion" # Too many warnings for now
nw="$nw -Wcast-qual"              # Too many warnings for now
nw="$nw -Waggregate-return"       # Too many warnings for now
nw="$nw -Wshadow"                 # Too many warnings for now
nw="$nw -Wswitch-default"         # Too many warnings for now
nw="$nw -Wswitch-enum"            # Too many warnings for now
nw="$nw -Wconversion"             # Too many warnings for now
nw="$nw -Wsign-conversion"        # Too many warnings for now
nw="$nw -Wformat-y2k"             # Too many warnings for now
nw="$nw -Wunsafe-loop-optimizations"
nw="$nw -Wstrict-overflow"
...
gl_WARN_ADD([-Wno-missing-field-initializers]) # We need this one
gl_WARN_ADD([-Wno-sign-compare])     # Too many warnings for now
gl_WARN_ADD([-Wno-pointer-sign])     # Too many warnings for now
gl_WARN_ADD([-Wno-unused-parameter]) # Too many warnings for now

GNU Shishi:

nw="$nw -Wsystem-headers"            # Ignore errors in system headers
nw="$nw -Wc++-compat"                # We don't care much about C++ compilers
nw="$nw -Wsign-conversion"           # Too many warnings for now
nw="$nw -Wconversion"                # Too many warnings for now
nw="$nw -Wpadded"                    # Our structs are not padded
nw="$nw -Wunreachable-code"          # Too many false positives
nw="$nw -Wlogical-op"                # Too many false positives
nw="$nw -Wtraditional"               # Warns on #elif which we use often
nw="$nw -Wtraditional-conversion"    # Too many warnings for now
nw="$nw -Wcast-qual"                 # Too many warnings for now
nw="$nw -Wmissing-format-attribute"  # Too many warnings for now
nw="$nw -Wunsafe-loop-optimizations" # Too many warnings for now
nw="$nw -Wundef"                     # Problems in gnulib files
nw="$nw -Wstrict-overflow"           # Don't know how to avoid
nw="$nw -Waggregate-return"          # For src/resume.c:resume_db_fetch...
...
gl_WARN_ADD([-Wno-unused-parameter]) # Too many warnings for now

GNU GSS:

nw="$nw -Wsystem-headers"            # Ignore errors in system headers
nw="$nw -Wc++-compat"                # We don't care much about C++ compilers
nw="$nw -Wconversion"                # Too many warnings for now
nw="$nw -Wsign-conversion"           # Too many warnings for now
nw="$nw -Wcast-qual"                 # Too many warnings for now
nw="$nw -Wtraditional"               # Warns on #elif which we use often
nw="$nw -Wunreachable-code"          # False positive on strcmp
...
gl_WARN_ADD([-Wno-unused-parameter])

Libntlm:

nw="$nw -Wsystem-headers"         # Don't let system headers trigger warnings
nw="$nw -Wconversion"             # Too many warnings for now
nw="$nw -Wsign-conversion"        # Too many warnings for now
nw="$nw -Wtraditional"            # Warns on #elif which we use often
nw="$nw -Wtraditional-conversion" # Too many warnings for now
nw="$nw -Wunreachable-code"       # Too many false positives
...
gl_WARN_ADD([-Wno-pointer-sign])     # Too many warnings for now

/Simon