3 files changed, 124 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;))
diff --git a/include/make/options.mk b/include/make/options.mk
new file mode 100644
index 0000000..022981c
--- /dev/null
+++ b/include/make/options.mk
@@ -0,0 +1,52 @@
+# this contains various functions and macros used to manipulate USE_* options
+# and their flags
+
+# Depending on the target platform, some options are set, as well as some
+# CFLAGS and LDFLAGS. All variables pre-set here will not appear in the build
+# options string. They may be set to any value, but are historically set to
+# "implicit" which eases debugging. You should not have to change anything
+# there unless you're adding support for a new platform.
+default_opts = $(foreach name,$(1),$(eval $(name)=implicit))
+
+# Return USE_xxx=$(USE_xxx) if the variable was set from the environment or the
+# command line.
+ignore_implicit = $(if $(subst environment,,$(origin $(1))),         \
+                       $(if $(subst command line,,$(origin $(1))),,  \
+                            $(1)=$($(1))),                           \
+                       $(1)=$($(1)))                                 \
+
+# This macro collects all USE_* values except those set to "implicit". This
+# is used to report a list of all flags which were used to build this version.
+# Do not assign anything to it.
+build_options   = $(foreach opt,$(use_opts),$(call ignore_implicit,$(opt)))
+
+# Make a list of all known features with +/- prepended depending on their
+# activation status. Must be a macro so that dynamically enabled ones are
+# evaluated with their current status.
+build_features  = $(foreach opt,$(patsubst USE_%,%,$(sort $(use_opts))),$(if $(USE_$(opt)),+$(opt),-$(opt)))
+
+# This returns a list of -DUSE_* for all known USE_* that are set
+opts_as_defines = $(foreach opt,$(use_opts),$(if $($(opt)),-D$(opt),))
+
+# Lists all enabled or disabled options without the "USE_" prefix
+enabled_opts    = $(foreach opt,$(patsubst USE_%,%,$(use_opts)),$(if $(USE_$(opt)),$(opt),))
+disabled_opts   = $(foreach opt,$(patsubst USE_%,%,$(use_opts)),$(if $(USE_$(opt)),,$(opt)))
+
+# preset all XXX_{INC,LIB,CFLAGS,LDFLAGS,SRC} variables to empty for $1=XXX
+reset_opt_vars = $(foreach name,INC LIB CFLAGS LDFLAGS SRC,$(eval $(1)_$(name)=))
+
+# preset all variables for all supported build options among use_opts
+reset_opts_vars = $(foreach opt,$(patsubst USE_%,%,$(use_opts)),$(call reset_opt_vars,$(opt)))
+
+# append $(1)_{C,LD}FLAGS into OPTIONS_{C,LD}FLAGS if not empty
+define collect_opt_flags
+  ifneq ($$($(1)_CFLAGS),)
+    OPTIONS_CFLAGS += $$($(1)_CFLAGS)
+  endif
+  ifneq ($$($(1)_LDFLAGS),)
+    OPTIONS_LDFLAGS += $$($(1)_LDFLAGS)
+  endif
+endef
+
+# collect all enabled USE_foo's foo_{C,LD}FLAGS into OPTIONS_{C,LD}FLAGS
+collect_opts_flags = $(foreach opt,$(enabled_opts),$(eval $(call collect_opt_flags,$(opt))))
diff --git a/include/make/verbose.mk b/include/make/verbose.mk
new file mode 100644
index 0000000..c37d513
--- /dev/null
+++ b/include/make/verbose.mk
@@ -0,0 +1,30 @@
+# verbosity: pass V=1 for verbose shell invocation
+V = 0
+Q = @
+ifeq ($V,1)
+Q=
+endif
+
+# Some common commands such as CC/LD/AR are redefined with a cmd_ equivalent
+# and are either mapped to a silent rule just indicating what is being done,
+# or to themselves depending on the verbosity level.
+ifeq ($V,1)
+cmd_CC = $(CC)
+cmd_LD = $(LD)
+cmd_AR = $(AR)
+cmd_MAKE = +$(MAKE)
+else
+ifeq (3.81,$(firstword $(sort $(MAKE_VERSION) 3.81)))
+# 3.81 or above
+cmd_CC = $(info $   CC      $@) $(Q)$(CC)
+cmd_LD = $(info $   LD      $@) $(Q)$(LD)
+cmd_AR = $(info $   AR      $@) $(Q)$(AR)
+cmd_MAKE = $(info $   MAKE    $@) $(Q)+$(MAKE)
+else
+# 3.80 or older
+cmd_CC = $(Q)echo "  CC      $@";$(CC)
+cmd_LD = $(Q)echo "  LD      $@";$(LD)
+cmd_AR = $(Q)echo "  AR      $@";$(AR)
+cmd_MAKE = $(Q)echo "  MAKE    $@";$(MAKE)
+endif
+endif