16f5d967e2
Having the compiler point out unreachable code can help avoid bugs, like the one discussed in: https://lore.kernel.org/git/20250307195057.GA3675279@coredump.intra.peff.net/ In that case it was found by Coverity, but finding it earlier saves everybody time and effort. We can use -Wunreachable-code to get some help from the compiler here. Interestingly, this is a noop in gcc. It was a real warning up until gcc 4.x, when it was removed for being too flaky, but they left the command-line option to avoid breaking users. See: https://stackoverflow.com/questions/17249934/why-does-gcc-not-warn-for-unreachable-code However, clang does implement this option, and it finds the case mentioned above (and no other cases within the code base). And since we run clang in several of our CI jobs, that's enough to get an early warning of breakage. We could enable it only for clang, but since gcc is happy to ignore it, it's simpler to just turn it on for all developer builds. Signed-off-by: Jeff King <peff@peff.net> [jc: squashed meson.build change sent by Patrick] Signed-off-by: Junio C Hamano <gitster@pobox.com>
103 lines
3.3 KiB
Plaintext
103 lines
3.3 KiB
Plaintext
ifndef COMPILER_FEATURES
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COMPILER_FEATURES := $(shell ./detect-compiler $(CC))
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endif
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ifeq ($(filter no-error,$(DEVOPTS)),)
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DEVELOPER_CFLAGS += -Werror
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SPARSE_FLAGS += -Wsparse-error
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endif
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DEVELOPER_CFLAGS += -Wall
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ifeq ($(filter no-pedantic,$(DEVOPTS)),)
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DEVELOPER_CFLAGS += -pedantic
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ifneq ($(or $(filter gcc5,$(COMPILER_FEATURES)),$(filter clang4,$(COMPILER_FEATURES))),)
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DEVELOPER_CFLAGS += -Wpedantic
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ifneq ($(filter gcc10,$(COMPILER_FEATURES)),)
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ifeq ($(uname_S),MINGW)
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DEVELOPER_CFLAGS += -Wno-pedantic-ms-format
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endif
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endif
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endif
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endif
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ifneq ($(uname_S),FreeBSD)
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ifneq ($(or $(filter gcc6,$(COMPILER_FEATURES)),$(filter clang7,$(COMPILER_FEATURES))),)
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DEVELOPER_CFLAGS += -std=gnu99
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endif
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else
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# FreeBSD cannot limit to C99 because its system headers unconditionally
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# rely on C11 features.
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endif
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DEVELOPER_CFLAGS += -Wdeclaration-after-statement
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DEVELOPER_CFLAGS += -Wformat-security
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DEVELOPER_CFLAGS += -Wold-style-definition
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DEVELOPER_CFLAGS += -Woverflow
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DEVELOPER_CFLAGS += -Wpointer-arith
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DEVELOPER_CFLAGS += -Wstrict-prototypes
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DEVELOPER_CFLAGS += -Wunused
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DEVELOPER_CFLAGS += -Wvla
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DEVELOPER_CFLAGS += -Wwrite-strings
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DEVELOPER_CFLAGS += -fno-common
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DEVELOPER_CFLAGS += -Wunreachable-code
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ifneq ($(filter clang4,$(COMPILER_FEATURES)),)
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DEVELOPER_CFLAGS += -Wtautological-constant-out-of-range-compare
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endif
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ifneq ($(or $(filter gcc6,$(COMPILER_FEATURES)),$(filter clang4,$(COMPILER_FEATURES))),)
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DEVELOPER_CFLAGS += -Wextra
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# if a function is public, there should be a prototype and the right
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# header file should be included. If not, it should be static.
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DEVELOPER_CFLAGS += -Wmissing-prototypes
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ifeq ($(filter extra-all,$(DEVOPTS)),)
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# These are disabled because we have these all over the place.
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DEVELOPER_CFLAGS += -Wno-empty-body
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DEVELOPER_CFLAGS += -Wno-missing-field-initializers
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endif
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endif
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# uninitialized warnings on gcc 4.9.2 in xdiff/xdiffi.c and config.c
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# not worth fixing since newer compilers correctly stop complaining
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#
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# Likewise, gcc older than 4.9 complains about initializing a
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# struct-within-a-struct using just "{ 0 }"
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ifneq ($(filter gcc4,$(COMPILER_FEATURES)),)
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ifeq ($(filter gcc5,$(COMPILER_FEATURES)),)
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DEVELOPER_CFLAGS += -Wno-uninitialized
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DEVELOPER_CFLAGS += -Wno-missing-braces
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endif
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endif
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# Old versions of clang complain about initializing a
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# struct-within-a-struct using just "{0}" rather than "{{0}}". This
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# error is considered a false-positive and not worth fixing, because
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# new clang versions do not, so just disable it.
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#
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# The "bug" was fixed in upstream clang 9.
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#
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# Complicating this is that versions of clang released by Apple have
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# their own version numbers (associated with the corresponding version
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# of XCode) unrelated to the official clang version numbers.
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#
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# The bug was fixed in Apple clang 12.
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#
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ifneq ($(filter clang1,$(COMPILER_FEATURES)),) # if we are using clang
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ifeq ($(uname_S),Darwin) # if we are on darwin
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ifeq ($(filter clang12,$(COMPILER_FEATURES)),) # if version < 12
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DEVELOPER_CFLAGS += -Wno-missing-braces
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endif
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else # not darwin
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ifeq ($(filter clang9,$(COMPILER_FEATURES)),) # if version < 9
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DEVELOPER_CFLAGS += -Wno-missing-braces
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endif
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endif
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endif
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# https://bugzilla.redhat.com/show_bug.cgi?id=2075786
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ifneq ($(filter gcc12,$(COMPILER_FEATURES)),)
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DEVELOPER_CFLAGS += -Wno-error=stringop-overread
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endif
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GIT_TEST_PERL_FATAL_WARNINGS = YesPlease
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