Makefile: restrict -Wpedantic and -Wno-pedantic-ms-format better

6a8cbc41ba (developer: enable pedantic by default, 2021-09-03)
enables pedantic mode in as many compilers as possible to help gather
feedback on future tightening, so lets do so.

-Wpedantic is missing in some really old gcc 4 versions so lets restrict
it to gcc5 and clang4 (it does work in clang3 AFAIK, but it will be
unlikely that a developer will use such an old compiler anyway).

MinGW gcc is the only one which has -Wno-pedantic-ms-format, and while
that is available also in older compilers, the Windows SDK provides gcc10
so lets aim for that.

Note that in order to target the flag to only Windows, additional changes
were needed in config.mak.uname to propagate the OS detection which also
did some minor refactoring, but which is functionaly equivalent.

Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.mak.dev

@@ -6,14 +6,19 @@ ifeq ($(filter no-error,$(DEVOPTS)),)
 DEVELOPER_CFLAGS += -Werror
 SPARSE_FLAGS += -Wsparse-error
 endif
+
 DEVELOPER_CFLAGS += -Wall
 ifeq ($(filter no-pedantic,$(DEVOPTS)),)
 DEVELOPER_CFLAGS += -pedantic
+ifneq (($or $(filter gcc5,$(COMPILER_FEATURES)),$(filter clang4,$(COMPILER_FEATURES))),)
 DEVELOPER_CFLAGS += -Wpedantic
-ifneq ($(filter gcc5,$(COMPILER_FEATURES)),)
+ifneq ($(filter gcc10,$(COMPILER_FEATURES)),)
+ifeq ($(uname_S),MINGW)
 DEVELOPER_CFLAGS += -Wno-pedantic-ms-format
 endif
 endif
+endif
+endif
 DEVELOPER_CFLAGS += -Wdeclaration-after-statement
 DEVELOPER_CFLAGS += -Wformat-security
 DEVELOPER_CFLAGS += -Wold-style-definition

config.mak.uname

@@ -11,6 +11,10 @@ uname_R := $(shell sh -c 'uname -r 2>/dev/null || echo not')
 uname_P := $(shell sh -c 'uname -p 2>/dev/null || echo not')
 uname_V := $(shell sh -c 'uname -v 2>/dev/null || echo not')
 
+ifneq ($(findstring MINGW,$(uname_S)),)
+	uname_S := MINGW
+endif
+
 ifdef MSVC
 	# avoid the MingW and Cygwin configuration sections
 	uname_S := Windows
@@ -588,7 +592,7 @@ ifeq ($(uname_S),NONSTOP_KERNEL)
 	SANE_TOOL_PATH = /usr/coreutils/bin:/usr/local/bin
 	SHELL_PATH = /usr/coreutils/bin/bash
 endif
-ifneq (,$(findstring MINGW,$(uname_S)))
+ifeq ($(uname_S),MINGW)
 	pathsep = ;
 	HAVE_ALLOCA_H = YesPlease
 	NO_PREAD = YesPlease