configure.ac: Fix compilation of Haiku's C++ convenience library

Commit 9a1bc8cafb ("build: Require C11 to build and clean up
autoconfig/automake files") added the language standard compiler option
to the AM_CFLAGS and AM_CXXFLAGS. Placing it in the latter is incorrect
as compiling C++ source with the C11 language standard does not make
sense.

Fix this by determining which C11 dialect (GNU or C) the compiler
supports and then constructing the compiler option from that.

Also restrict LT_LDFLAGS to the final libusb library (as was done
previously) since libtool complains about versioning options for
convenience libraries.

Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>

3 files changed, 18 insertions, 21 deletions

diff --git a/configure.ac b/configure.ac
index 32f4244..d2d5b6f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -38,34 +38,31 @@ LT_LDFLAGS="-version-info ${lt_current}:${lt_revision}:${lt_age} -no-undefined"
 
 m4_ifdef([AM_SILENT_RULES],[AM_SILENT_RULES([yes])])
 
+EXTRA_CFLAGS=
+
 dnl check for -std=gnu11 compiler support (optional)
-dnl note that we don't just check whether the compiler accepts '-std=x11'
+dnl note that we don't just check if the compiler accepts '-std=x11'
 dnl but also that it supports the _Thread_local keyword because some compilers
 dnl (e.g. gcc 4.8) accept the command line option but do not implement TLS
 saved_CFLAGS="${CFLAGS}"
 CFLAGS="-std=gnu11"
-AC_MSG_CHECKING([whether CC supports -std=gnu11])
+AC_MSG_CHECKING([if $CC supports -std=gnu11])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([_Thread_local int x;], [x = 42;])],
 	[AC_MSG_RESULT([yes])
-	 cc_supports_gnu11=yes],
+	 c_dialect=gnu],
 	[AC_MSG_RESULT([no])
-	 cc_supports_gnu11=])
-CFLAGS="${saved_CFLAGS}"
-
-if test "x$cc_supports_gnu11" = xyes; then
-	AM_CFLAGS="-std=gnu11"
-else
+	 c_dialect=])
+if test "x$c_dialect" != xgnu; then
 	dnl fallback check for -std=c11 compiler support (required)
-	saved_CFLAGS="${CFLAGS}"
 	CFLAGS="-std=c11"
-	AC_MSG_CHECKING([whether CC supports -std=c11])
+	AC_MSG_CHECKING([if $CC supports -std=c11])
 	AC_COMPILE_IFELSE([AC_LANG_PROGRAM([_Thread_local int x;], [x = 42;])],
 		[AC_MSG_RESULT([yes])],
 		[AC_MSG_RESULT([no])
 		 AC_MSG_ERROR([compiler with C11 support is required to build libusb])])
-	CFLAGS="${saved_CFLAGS}"
-	AM_CFLAGS="-std=c11"
+	c_dialect=c
 fi
+CFLAGS="${saved_CFLAGS}"
 
 AC_DEFINE([_GNU_SOURCE], [1], [Enable GNU extensions.])
 AC_DEFINE([DEFAULT_VISIBILITY], [__attribute__ ((visibility ("default")))], [Define to the attribute for default visibility.])
@@ -131,7 +128,7 @@ case $host in
 	poll=windows
 	threads=windows
 	test "x$enable_shared" = xyes && create_import_lib=yes
-	AM_CFLAGS="${AM_CFLAGS} -fno-omit-frame-pointer"
+	EXTRA_CFLAGS="-fno-omit-frame-pointer"
 	;;
 *)
 	AC_MSG_RESULT([Null])
@@ -318,23 +315,23 @@ AM_CONDITIONAL([THREADS_POSIX], [test "x$threads" = xposix])
 AM_CONDITIONAL([THREADS_WINDOWS], [test "x$threads" = xwindows])
 AM_CONDITIONAL([USE_UDEV], [test "x$use_udev" = xyes])
 
-EXTRA_CFLAGS=
-
 dnl The -Wcast-function-type warning causes a flurry of warnings when compiling
 dnl Windows with GCC 8 or later because of dynamically loaded functions
 if test "x$backend" = xwindows; then
 	saved_CFLAGS="${CFLAGS}"
 	CFLAGS="-Werror -Wcast-function-type"
 	AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [])],
-		[EXTRA_CFLAGS="-Wno-cast-function-type"],
+		[EXTRA_CFLAGS="${EXTRA_CFLAGS} -Wno-cast-function-type"],
 		[])
 	CFLAGS="${saved_CFLAGS}"
 fi
 
-AM_CFLAGS="${AM_CFLAGS} -Wall -Wextra -Wshadow -Wunused -Wwrite-strings -Werror=format-security -Werror=implicit-function-declaration -Werror=implicit-int -Werror=init-self -Werror=missing-prototypes -Werror=strict-prototypes -Werror=undef -Werror=uninitialized ${EXTRA_CFLAGS}"
+SHARED_CFLAGS="-Wall -Wextra -Wshadow -Wunused -Wwrite-strings -Werror=format-security -Werror=implicit-function-declaration -Werror=implicit-int -Werror=init-self -Werror=missing-prototypes -Werror=strict-prototypes -Werror=undef -Werror=uninitialized"
+
+AM_CFLAGS="-std=${c_dialect}11 ${EXTRA_CFLAGS} ${SHARED_CFLAGS}"
 AC_SUBST(AM_CFLAGS)
 
-AM_CXXFLAGS="${AM_CFLAGS} -Wmissing-declarations"
+AM_CXXFLAGS="-std=${c_dialect}++11 ${EXTRA_CFLAGS} ${SHARED_CFLAGS} -Wmissing-declarations"
 AC_SUBST(AM_CXXFLAGS)
 
 AC_SUBST(LT_LDFLAGS)
diff --git a/libusb/Makefile.am b/libusb/Makefile.am
index 9432c62..6b93343 100644
--- a/libusb/Makefile.am
+++ b/libusb/Makefile.am
@@ -2,7 +2,6 @@ AUTOMAKE_OPTIONS = subdir-objects
 
 AM_CFLAGS += -fvisibility=hidden $(THREAD_CFLAGS)
 AM_CXXFLAGS += -fvisibility=hidden $(THREAD_CFLAGS)
-AM_LDFLAGS = $(LT_LDFLAGS)
 
 lib_LTLIBRARIES = libusb-1.0.la
 
@@ -88,6 +87,7 @@ all-local: .libs/libusb-1.0.dll.a
 endif
 endif
 
+libusb_1_0_la_LDFLAGS = $(LT_LDFLAGS)
 libusb_1_0_la_SOURCES = libusbi.h version.h version_nano.h \
 	core.c descriptor.c hotplug.h hotplug.c io.c strerror.c sync.c \
 	$(POLL_SRC) $(THREADS_SRC) $(OS_SRC)
diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index 6281b80..232a43c 100644
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 11486
+#define LIBUSB_NANO 11487