The set of extra warnings we enable when DEVELOPER has to be
conservative because we can't assume any compiler version the
developer may use. Detect the compiler version so we know when it's
safe to enable -Wextra and maybe more.
Helped-by: Jeff King <peff@xxxxxxxx>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
---
-dumpversion does not work correctly for clang. So I use "-v" instead
which seems to produce the same output for both gcc and clang (with a
minor difference in freebsd where it says "FreeBSD clang" instead of
just "clang"). Not sure if it helps your "cc on debian" case though
Tested with clang-5.0.1 and gcc-6.4.0 (too lazy to test on freebsd
clang 3.4.1 but I don't expect surprises there)
I will still need to pull more modern gcc/clang on travis, but that
can wait until this patch settles.
Makefile | 11 +----------
config.mak.dev | 28 +++++++++++++++++++++++++++
detect-compiler | 50 +++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 79 insertions(+), 10 deletions(-)
create mode 100644 config.mak.dev
create mode 100755 detect-compiler
diff --git a/Makefile b/Makefile
index a1d8775adb..9dfd152a1e 100644
--- a/Makefile
+++ b/Makefile
@@ -442,15 +442,6 @@ GIT-VERSION-FILE: FORCE
# CFLAGS and LDFLAGS are for the users to override from the command line.
CFLAGS = -g -O2 -Wall
-DEVELOPER_CFLAGS = -Werror \
- -Wdeclaration-after-statement \
- -Wno-format-zero-length \
- -Wold-style-definition \
- -Woverflow \
- -Wpointer-arith \
- -Wstrict-prototypes \
- -Wunused \
- -Wvla
LDFLAGS =
ALL_CFLAGS = $(CPPFLAGS) $(CFLAGS)
ALL_LDFLAGS = $(LDFLAGS)
@@ -1051,7 +1042,7 @@ include config.mak.uname
-include config.mak
ifdef DEVELOPER
-CFLAGS += $(DEVELOPER_CFLAGS)
+include config.mak.dev
endif
comma := ,
diff --git a/config.mak.dev b/config.mak.dev
new file mode 100644
index 0000000000..59aef342c4
--- /dev/null
+++ b/config.mak.dev
@@ -0,0 +1,28 @@
+CFLAGS += -Werror
+CFLAGS += -Wdeclaration-after-statement
+CFLAGS += -Wno-format-zero-length
+CFLAGS += -Wold-style-definition
+CFLAGS += -Woverflow
+CFLAGS += -Wpointer-arith
+CFLAGS += -Wstrict-prototypes
+CFLAGS += -Wunused
+CFLAGS += -Wvla
+
+COMPILER_FEATURES := $(shell ./detect-compiler $(CC))
+
+ifneq ($(filter clang4,$(COMPILER_FEATURES)),)
+CFLAGS += -Wtautological-constant-out-of-range-compare
+endif
+
+ifneq ($(or $(filter gcc6,$(COMPILER_FEATURES)),$(filter clang4,$(COMPILER_FEATURES))),)
+CFLAGS += -Wextra
+CFLAGS += -Wmissing-prototypes
+CFLAGS += -Wno-empty-body
+CFLAGS += -Wno-missing-field-initializers
+CFLAGS += -Wno-sign-compare
+CFLAGS += -Wno-unused-function
+CFLAGS += -Wno-unused-parameter
+ifneq ($(filter gcc6,$(COMPILER_FEATURES)),)
+CFLAGS += -Wno-maybe-uninitialized
+endif
+endif
diff --git a/detect-compiler b/detect-compiler
new file mode 100755
index 0000000000..bc2ea39ef5
--- /dev/null
+++ b/detect-compiler
@@ -0,0 +1,50 @@
+#!/bin/sh
+#
+# Probe the compiler for vintage, version, etc. This is used for setting
+# optional make knobs under the DEVELOPER knob.
+
+CC="$*"
+
+# we get something like (this is at least true for gcc and clang)
+#
+# FreeBSD clang version 3.4.1 (tags/RELEASE...)
+get_version_line() {
+ "$CC" -v 2>&1 | grep ' version '
+}
+
+get_family() {
+ get_version_line | sed 's/^\(.*\) version [0-9][^ ]* .*/\1/'
+}
+
+get_version() {
+ get_version_line | sed 's/^.* version \([0-9][^ ]*\) .*/\1/'
+}
+
+print_flags() {
+ family=$1
+ version=$(get_version | cut -f 1 -d .)
+
+ # Print a feature flag not only for the current version, but also
+ # for any prior versions we encompass. This avoids needing to do
+ # numeric comparisons in make, which are awkward.
+ while test "$version" -gt 0
+ do
+ echo $family$version
+ version=$((version - 1))
+ done
+}
+
+case "$(get_family)" in
+gcc)
+ print_flags gcc
+ ;;
+*clang)
+ print_flags clang
+ ;;
+"FreeBSD clang")
+ print_flags clang
+ ;;
+*)
+ : unknown compiler family
+ ;;
+esac
--
2.17.0.rc0.347.gf9cf61673a
