Commit 6d5d4b4e authored by Ævar Arnfjörð Bjarmason's avatar Ævar Arnfjörð Bjarmason Committed by Junio C Hamano

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.htmlSigned-off-by: Ævar Arnfjörð Bjarmason's avatarÆvar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: default avatarJunio C Hamano <gitster@pobox.com>
parent 71a7894b
......@@ -479,7 +479,11 @@ all::
#
# Define DEVELOPER to enable more compiler warnings. Compiler version
# and family are auto detected, but could be overridden by defining
# COMPILER_FEATURES (see config.mak.dev)
# COMPILER_FEATURES (see config.mak.dev). You can still set
# CFLAGS="..." in combination with DEVELOPER enables, whether that's
# for tweaking something unrelated (e.g. optimization level), or for
# selectively overriding something DEVELOPER or one of the DEVOPTS
# (see just below) brings in.
#
# When DEVELOPER is set, DEVOPTS can be used to control compiler
# options. This variable contains keywords separated by
......@@ -1169,7 +1173,7 @@ ifdef DEVELOPER
include config.mak.dev
endif
ALL_CFLAGS = $(CPPFLAGS) $(CFLAGS)
ALL_CFLAGS = $(DEVELOPER_CFLAGS) $(CPPFLAGS) $(CFLAGS)
ALL_LDFLAGS = $(LDFLAGS)
comma := ,
......
ifeq ($(filter no-error,$(DEVOPTS)),)
CFLAGS += -Werror
DEVELOPER_CFLAGS += -Werror
endif
ifneq ($(filter pedantic,$(DEVOPTS)),)
CFLAGS += -pedantic
DEVELOPER_CFLAGS += -pedantic
# don't warn for each N_ use
CFLAGS += -DUSE_PARENS_AROUND_GETTEXT_N=0
endif
CFLAGS += -Wall
CFLAGS += -Wdeclaration-after-statement
CFLAGS += -Wformat-security
CFLAGS += -Wno-format-zero-length
CFLAGS += -Wold-style-definition
CFLAGS += -Woverflow
CFLAGS += -Wpointer-arith
CFLAGS += -Wstrict-prototypes
CFLAGS += -Wunused
CFLAGS += -Wvla
DEVELOPER_CFLAGS += -DUSE_PARENS_AROUND_GETTEXT_N=0
endif
DEVELOPER_CFLAGS += -Wall
DEVELOPER_CFLAGS += -Wdeclaration-after-statement
DEVELOPER_CFLAGS += -Wformat-security
DEVELOPER_CFLAGS += -Wno-format-zero-length
DEVELOPER_CFLAGS += -Wold-style-definition
DEVELOPER_CFLAGS += -Woverflow
DEVELOPER_CFLAGS += -Wpointer-arith
DEVELOPER_CFLAGS += -Wstrict-prototypes
DEVELOPER_CFLAGS += -Wunused
DEVELOPER_CFLAGS += -Wvla
ifndef COMPILER_FEATURES
COMPILER_FEATURES := $(shell ./detect-compiler $(CC))
endif
ifneq ($(filter clang4,$(COMPILER_FEATURES)),)
CFLAGS += -Wtautological-constant-out-of-range-compare
DEVELOPER_CFLAGS += -Wtautological-constant-out-of-range-compare
endif
ifneq ($(or $(filter gcc6,$(COMPILER_FEATURES)),$(filter clang4,$(COMPILER_FEATURES))),)
CFLAGS += -Wextra
DEVELOPER_CFLAGS += -Wextra
# if a function is public, there should be a prototype and the right
# header file should be included. If not, it should be static.
CFLAGS += -Wmissing-prototypes
DEVELOPER_CFLAGS += -Wmissing-prototypes
ifeq ($(filter extra-all,$(DEVOPTS)),)
# These are disabled because we have these all over the place.
CFLAGS += -Wno-empty-body
CFLAGS += -Wno-missing-field-initializers
CFLAGS += -Wno-sign-compare
CFLAGS += -Wno-unused-parameter
DEVELOPER_CFLAGS += -Wno-empty-body
DEVELOPER_CFLAGS += -Wno-missing-field-initializers
DEVELOPER_CFLAGS += -Wno-sign-compare
DEVELOPER_CFLAGS += -Wno-unused-parameter
endif
endif
......@@ -43,6 +43,6 @@ endif
# not worth fixing since newer compilers correctly stop complaining
ifneq ($(filter gcc4,$(COMPILER_FEATURES)),)
ifeq ($(filter gcc5,$(COMPILER_FEATURES)),)
CFLAGS += -Wno-uninitialized
DEVELOPER_CFLAGS += -Wno-uninitialized
endif
endif
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