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Diffstat (limited to 'include/make/compiler.mk')
| -rw-r--r-- | include/make/compiler.mk | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/include/make/compiler.mk b/include/make/compiler.mk new file mode 100644 index 0000000..f251693 --- /dev/null +++ b/include/make/compiler.mk @@ -0,0 +1,42 @@ +# WARNING: Do not change cc-opt, cc-opt-alt or cc-warning without checking if +# clang bug #49364 is fixed. stderr is redirected to /dev/null on +# purpose, to work around a clang 11 bug that crashes if stderr is +# redirected to stdin. +# +# Function used to detect support of a given option by the compiler. +# Usage: CFLAGS += $(call cc-opt,option). Eg: $(call cc-opt,-fwrapv) +# Note: ensure the referencing variable is assigned using ":=" and not "=" to +# call it only once. +cc-opt = $(shell set -e; if $(CC) -Werror $(1) -E -xc - -o /dev/null </dev/null >&0 2>/dev/null; then echo "$(1)"; fi;) + +# same but tries with $2 if $1 is not supported +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))) + +# validate a list of options one at a time +cc-all-opts = $(foreach a,$(1),$(call cc-opt,$(a))) + +# try to pass plenty of options at once, take them on success or try them +# one at a time on failure and keep successful ones. This is handy to quickly +# validate most common options. +cc-all-fast = $(if $(call cc-opt,$(1)),$(1),$(call cc-all-opts,$(1))) + +# Below we verify that the compiler supports any -Wno-something option to +# disable any warning, or if a special option is needed to achieve that. This +# will allow to get rid of testing when the compiler doesn't care. The result +# is made of two variables: +# - cc-anywno that's non-empty if the compiler supports disabling anything +# - cc-wnouwo that may contain an option needed to enable this behavior +# Gcc 4.x and above do not need any option but will still complain about unknown +# options if another warning or error happens, and as such they're not testable. +# Clang needs a special option -Wno-unknown-warning-option. Compilers not +# supporting this option will check all warnings individually. +cc-anywno := $(call cc-opt,-Wno-haproxy-warning) +cc-wnouwo := $(if $(cc-anywno),,$(call cc-opt,-Wno-unknown-warning-option)) +cc-anywno := $(if $(cc-anywno)$(cc-wnouwo),1) + +# Disable a warning when supported by the compiler. Don't put spaces around the +# warning! And don't use cc-opt which doesn't always report an error until +# another one is also returned. If "cc-anywno" is set, the compiler supports +# -Wno- followed by anything so we don't even need to start the compiler. +# Usage: CFLAGS += $(call cc-nowarn,warning). Eg: $(call cc-opt,format-truncation) +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;)) |