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Ævar Arnfjörð Bjarmason 6d5d4b4e93 Makefile: allow for combining DEVELOPER=1 and CFLAGS="..."
Ever since the DEVELOPER=1 facility introduced there's been no way to
have custom CFLAGS (e.g. CFLAGS="-O0 -g -ggdb3") while still
benefiting from the set of warnings and assertions DEVELOPER=1
enables.

This is because the semantics of variables in the Makefile are such
that the user setting CFLAGS overrides anything we set, including what
we're doing in config.mak.dev[1].

So let's introduce a "DEVELOPER_CFLAGS" variable in config.mak.dev and
add it to ALL_CFLAGS. Before this the ALL_CFLAGS variable
would (basically, there's some nuance we won't go into) be set to:

    $(CPPFLAGS) [$(CFLAGS) *or* $(CFLAGS) in config.mak.dev] $(BASIC_CFLAGS) $(EXTRA_CPPFLAGS)

But will now be:

    $(DEVELOPER_CFLAGS) $(CPPFLAGS) $(CFLAGS) $(BASIC_CFLAGS) $(EXTRA_CPPFLAGS)

The reason for putting DEVELOPER_CFLAGS first is to allow for
selectively overriding something DEVELOPER=1 brings in. On both GCC
and Clang later settings override earlier ones. E.g. "-Wextra
-Wno-extra" will enable no "extra" warnings, but not if those two
arguments are reversed.

Examples of things that weren't possible before, but are now:

    # Use -O0 instead of -O2 for less painful debuggng
    DEVELOPER=1 CFLAGS="-O0 -g"
    # DEVELOPER=1 plus -Wextra, but disable some of the warnings
    DEVELOPER=1 DEVOPTS="no-error extra-all" CFLAGS="-O0 -g -Wno-unused-parameter"

The reason for the patches leading up to this one re-arranged the
various *FLAGS assignments and includes is just for readability. The
Makefile supports assignments out of order, e.g.:

    $ cat Makefile
    X = $(A) $(B) $(C)
    A = A
    B = B
    include c.mak
    all:
            @echo $(X)
    $ cat c.mak
    C=C
    $ make
    A B C

So we could have gotten away with the much smaller change of changing
"CFLAGS" in config.mak.dev to "DEVELOPER_CFLAGS" and adding that to
ALL_CFLAGS earlier in the Makefile "before" the config.mak.*
includes. But I think it's more readable to use variables "after"
they're included.

1. https://www.gnu.org/software/make/manual/html_node/Overriding.html

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-02-24 07:35:07 -08:00
Junio C Hamano 74ae0652c4 Merge branch 'jk/dev-build-format-security'
Earlier we added "-Wformat-security" to developer builds, assuming
that "-Wall" (which includes "-Wformat" which in turn is required
to use "-Wformat-security") is always in effect.  This is not true
when config.mak.autogen is in use, unfortunately.  This has been
fixed by unconditionally adding "-Wall" to developer builds.

* jk/dev-build-format-security:
  config.mak.dev: add -Wall, primarily for -Wformat, to help autoconf users
2019-01-18 13:49:55 -08:00
Thomas Gummerer 6163f3f1a4 config.mak.dev: add -Wall, primarily for -Wformat, to help autoconf users
801fa63a90 ("config.mak.dev: add -Wformat-security", 2018-09-08)
added the "-Wformat-security" to the flags set in config.mak.dev.
In the gcc man page this is documented as:

         If -Wformat is specified, also warn about uses of format
         functions that represent possible security problems.  [...]

The commit did however not add the "-Wformat" flag, but instead
relied on the fact that "-Wall" is set in the Makefile by default
and that "-Wformat" is part of "-Wall".

Unfortunately, those who use config.mak.autogen generated with the
autoconf to configure toolchain do *not* get "-Wall" in their CFLAGS
and the added -Wformat-security had no effect.  Worse yet, newer
versions of gcc (gcc 8.2.1 in this particular case) warn about the
lack of "-Wformat" and thus compilation fails only with this option
set.

We could fix it by adding "-Wformat", but in general we do want all
checks included in "-Wall", so let's add it to config.mak.dev to
cover more cases.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Helped-by: Jeff King <peff@peff.net>
Helped-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-01-07 09:02:08 -08:00
Junio C Hamano c5cde07a71 Merge branch 'jk/unused-function'
Developer support.

* jk/unused-function:
  config.mak.dev: enable -Wunused-function
2018-10-30 15:43:46 +09:00
Jeff King 36da893114 config.mak.dev: enable -Wunused-function
We explicitly omitted -Wunused-function when we added
-Wextra, but there is no need: the current code compiles
cleanly with it. And it's worth having, since it can let you
know when there are cascading effects from a cleanup (e.g.,
deleting one function lets you delete its static helpers).

There are cases where we may need an unused function to
exist, but we can handle these easily:

  - macro-generated code like commit-slab; there we have the
    MAYBE_UNUSED annotation to silence the compiler

  - conditional compilation, where we may or may not need a
    static helper. These generally fall into one of two
    categories:

      - the call should not be conditional, but rather the
	function body itself should be (and may just be a
	no-op on one side of the #if). That keeps the
	conditional pollution out of the main code.

      - call-chains of static helpers should all be in the
        same #if block, so they are all-or-nothing

    And if there's some case that doesn't cover, we still
    have MAYBE_UNUSED as a fallback.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-10-19 10:24:11 +09:00
Junio C Hamano 2bdbe4a2c3 Merge branch 'jk/dev-build-format-security'
Build tweak to help developers.

* jk/dev-build-format-security:
  config.mak.dev: add -Wformat-security
2018-09-24 10:30:49 -07:00
Jeff King 801fa63a90 config.mak.dev: add -Wformat-security
We currently build cleanly with -Wformat-security, and it's
a good idea to make sure we continue to do so (since calls
that trigger the warning may be security vulnerabilities).

Note that we cannot use the stronger -Wformat-nonliteral, as
there are case where we are clever with passing around
pointers to string literals. E.g., bisect_rev_setup() takes
bad_format and good_format parameters. These ultimately come
from literals, but they still trigger the warning.

Some of these might be fixable (e.g., by passing flags from
which we locally select a format), and might even be worth
fixing (not because of security, but just because it's an
easy mistake to pass the wrong format). But there are other
cases which are likely quite hard to fix (we actually
generate formats in a local buffer in some cases). So let's
punt on that for now and start with -Wformat-security, which
is supposed to catch the most important cases.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-09-11 12:50:21 -07:00
Beat Bolli 729b3925ed Makefile: add a DEVOPTS flag to get pedantic compilation
In the interest of code hygiene, make it easier to compile Git with the
flag -pedantic.

Pure pedantic compilation with GCC 7.3 results in one warning per use of
the translation macro `N_`:

    warning: array initialized from parenthesized string constant [-Wpedantic]

Therefore also disable the parenthesising of i18n strings with
-DUSE_PARENS_AROUND_GETTEXT_N=0.

Signed-off-by: Beat Bolli <dev+git@drbeat.li>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-07-25 09:52:32 -07:00
Ævar Arnfjörð Bjarmason 26d2e4fb22 Makefile: add a DEVOPTS to get all of -Wextra
Change DEVOPTS to understand a "extra-all" option. When the DEVELOPER
flag is enabled we turn on -Wextra, but manually switch some of the
warnings it turns on off.

This is because we have many existing occurrences of them in the code
base. This mode will stop the suppression, let the developer see and
decide whether to  fix them.

This change is a slight alteration of Nguyễn Thái Ngọc Duy
EAGER_DEVELOPER mode patch[1]

1. "[PATCH v3 3/3] Makefile: add EAGER_DEVELOPER
    mode" (<20180329150322.10722-4-pclouds@gmail.com>;
    https://public-inbox.org/git/20180329150322.10722-4-pclouds@gmail.com/)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-04-16 13:54:53 +09:00
Ævar Arnfjörð Bjarmason 99f763baf5 Makefile: add a DEVOPTS to suppress -Werror under DEVELOPER
Add a DEVOPTS variable that'll be used to tweak the behavior of
DEVELOPER.

I've long wanted to use DEVELOPER=1 in my production builds, but on
some old systems I still get warnings, and thus the build would
fail. However if the build/tests fail for some other reason, it would
still be useful to scroll up and see what the relevant code is warning
about.

This change allows for that. Now setting DEVELOPER will set -Werror as
before, but if DEVOPTS=no-error is provided is set you'll get the same
warnings, but without -Werror.

Helped-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-04-16 13:54:53 +09:00
Nguyễn Thái Ngọc Duy 1da1580e4c Makefile: detect compiler and enable more warnings in DEVELOPER=1
The set of extra warnings we enable when DEVELOPER has to be
conservative because we can't assume any compiler version the
developer may use. Detect the compiler version so we know when it's
safe to enable -Wextra and maybe more.

These warning settings are mostly from my custom config.mak a long
time ago when I tried to enable as many warnings as possible that can
still build without showing warnings. Some of those warnings are
probably worth fixing instead of just suppressing in future.

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-04-16 13:54:53 +09:00