43 lines
2.5 KiB
Makefile
43 lines
2.5 KiB
Makefile
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# WARNING: Do not change cc-opt, cc-opt-alt or cc-warning without checking if
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# clang bug #49364 is fixed. stderr is redirected to /dev/null on
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# purpose, to work around a clang 11 bug that crashes if stderr is
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# redirected to stdin.
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#
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# Function used to detect support of a given option by the compiler.
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# Usage: CFLAGS += $(call cc-opt,option). Eg: $(call cc-opt,-fwrapv)
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# Note: ensure the referencing variable is assigned using ":=" and not "=" to
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# call it only once.
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cc-opt = $(shell set -e; if $(CC) -Werror $(1) -E -xc - -o /dev/null </dev/null >&0 2>/dev/null; then echo "$(1)"; fi;)
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# same but tries with $2 if $1 is not supported
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cc-opt-alt = $(if $(shell set -e; if $(CC) -Werror $(1) -E -xc - -o /dev/null </dev/null >&0 2>/dev/null; then echo 1;fi),$(1),$(call cc-opt,$(2)))
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# validate a list of options one at a time
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cc-all-opts = $(foreach a,$(1),$(call cc-opt,$(a)))
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# try to pass plenty of options at once, take them on success or try them
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# one at a time on failure and keep successful ones. This is handy to quickly
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# validate most common options.
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cc-all-fast = $(if $(call cc-opt,$(1)),$(1),$(call cc-all-opts,$(1)))
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# Below we verify that the compiler supports any -Wno-something option to
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# disable any warning, or if a special option is needed to achieve that. This
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# will allow to get rid of testing when the compiler doesn't care. The result
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# is made of two variables:
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# - cc-anywno that's non-empty if the compiler supports disabling anything
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# - cc-wnouwo that may contain an option needed to enable this behavior
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# Gcc 4.x and above do not need any option but will still complain about unknown
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# options if another warning or error happens, and as such they're not testable.
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# Clang needs a special option -Wno-unknown-warning-option. Compilers not
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# supporting this option will check all warnings individually.
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cc-anywno := $(call cc-opt,-Wno-haproxy-warning)
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cc-wnouwo := $(if $(cc-anywno),,$(call cc-opt,-Wno-unknown-warning-option))
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cc-anywno := $(if $(cc-anywno)$(cc-wnouwo),1)
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# Disable a warning when supported by the compiler. Don't put spaces around the
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# warning! And don't use cc-opt which doesn't always report an error until
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# another one is also returned. If "cc-anywno" is set, the compiler supports
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# -Wno- followed by anything so we don't even need to start the compiler.
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# Usage: CFLAGS += $(call cc-nowarn,warning). Eg: $(call cc-opt,format-truncation)
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cc-nowarn = $(if $(cc-anywno),-Wno-$(1),$(shell set -e; if $(CC) -Werror -W$(1) -E -xc - -o /dev/null </dev/null >&0 2>/dev/null; then echo "-Wno-$(1)"; fi;))
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