[PATCH v2 6/6] 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 CSo 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.html
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
Makefile | 8 ++++++--
config.mak.dev | 44 ++++++++++++++++++++++----------------------
2 files changed, 28 insertions(+), 24 deletions(-)
Show changes to 2 files +28 −24
Makefile, config.mak.dev
diff --git a/Makefile b/Makefile
index 82cfd6c2e4..710a3475a9 100644
--- a/Makefile
+++ b/Makefile
@@ -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 = $(LDFLAGS)
comma := ,
diff --git a/config.mak.dev b/config.mak.dev
index 7354fe15b3..bf1f3fcdee 100644
--- a/config.mak.dev
+++ b/config.mak.dev
@@ -1,41 +1,41 @@
ifeq ($(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
--
2.21.0.rc2.1.g2d5e20a900.dirty
Ævar Arnfjörð Bjarmason
