From: Antonio Ospite <ao2@ao2.it>
Date: Tue, 27 Feb 2018 16:03:36 +0000 (+0100)
Subject: am7xxx: fix C99 conformance for printf & co. when compiling with MinGW
X-Git-Tag: v0.1.7~17
X-Git-Url: https://git.ao2.it/libam7xxx.git/commitdiff_plain/bbebd199987581ee6f344c89bfb02237dc0ab0bd?ds=sidebyside;hp=bdf46231090f97e1d941b5b24078fc40140738c4

am7xxx: fix C99 conformance for printf & co. when compiling with MinGW

C99 format specifiers like "%hhd" are used with log_message() but MinGW
(and Windows) does not really supports them, so the compiler suggests to
use the "gnu_printf" attribute for the function.

However "gnu_printf"is not available on clang so it's not an option,
a better alternative is the solution suggested by MinGW at
https://sourceforge.net/p/mingw-w64/wiki2/gnu%20printf/

The change fixes the following warnings when compiling with MinGW:

.../libam7xxx/src/am7xxx.c: In function ‘log_message’:
.../libam7xxx/src/am7xxx.c:647:3: warning: function ‘log_message’ might be a candidate for ‘gnu_printf’ format attribute [-Wsuggest-attribute=format]
   vfprintf(stderr, fmt, ap);
   ^~~~~~~~
.../libam7xxx/src/am7xxx.c: In function ‘open_device’:
.../libam7xxx/src/am7xxx.c:772:15: warning: unknown conversion type character ‘h’ in format [-Wformat=]
    debug(ctx, "Cannot set configuration %hhu\n",
               ^
.../libam7xxx/src/am7xxx.c:65:85: note: in definition of macro ‘debug’
 #define debug(ctx, ...)   log_message(ctx,  AM7XXX_LOG_DEBUG,   __func__, 0,        __VA_ARGS__)
                                                                                     ^~~~~~~~~~~
.../libam7xxx/src/am7xxx.c:772:15: warning: too many arguments for format [-Wformat-extra-args]
    debug(ctx, "Cannot set configuration %hhu\n",
               ^
.../libam7xxx/src/am7xxx.c:65:85: note: in definition of macro ‘debug’
 #define debug(ctx, ...)   log_message(ctx,  AM7XXX_LOG_DEBUG,   __func__, 0,        __VA_ARGS__)
                                                                                     ^~~~~~~~~~~
.../libam7xxx/src/am7xxx.c:785:14: warning: unknown conversion type character ‘h’ in format [-Wformat=]
   debug(ctx, "Cannot claim interface %hhu\n",
              ^
.../libam7xxx/src/am7xxx.c:65:85: note: in definition of macro ‘debug’
 #define debug(ctx, ...)   log_message(ctx,  AM7XXX_LOG_DEBUG,   __func__, 0,        __VA_ARGS__)
                                                                                     ^~~~~~~~~~~
.../libam7xxx/src/am7xxx.c:785:14: warning: too many arguments for format [-Wformat-extra-args]
   debug(ctx, "Cannot claim interface %hhu\n",
              ^
.../libam7xxx/src/am7xxx.c:65:85: note: in definition of macro ‘debug’
 #define debug(ctx, ...)   log_message(ctx,  AM7XXX_LOG_DEBUG,   __func__, 0,        __VA_ARGS__)
                                                                                     ^~~~~~~~~~~
.../libam7xxx/src/am7xxx.c:803:14: warning: unknown conversion type character ‘h’ in format [-Wformat=]
   debug(ctx, "libusb configuration changed (expected: %hhu, current: %d)\n",
              ^
.../libam7xxx/src/am7xxx.c:65:85: note: in definition of macro ‘debug’
 #define debug(ctx, ...)   log_message(ctx,  AM7XXX_LOG_DEBUG,   __func__, 0,        __VA_ARGS__)
                                                                                     ^~~~~~~~~~~
.../libam7xxx/src/am7xxx.c:803:14: warning: too many arguments for format [-Wformat-extra-args]
   debug(ctx, "libusb configuration changed (expected: %hhu, current: %d)\n",
              ^
.../libam7xxx/src/am7xxx.c:65:85: note: in definition of macro ‘debug’
 #define debug(ctx, ...)   log_message(ctx,  AM7XXX_LOG_DEBUG,   __func__, 0,        __VA_ARGS__)
                                                                                     ^~~~~~~~~~~
---

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 15c1f6f..d6cdaad 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,6 +1,10 @@
 add_definitions("-D_DEFAULT_SOURCE") # for htole32()
 add_definitions("-D_POSIX_C_SOURCE=200112L") # for nanosleep() and lroundf()
 
+# Express a preference for C99 format strings when using MinGW, see:
+# https://sourceforge.net/p/mingw-w64/wiki2/gnu%20printf/
+add_definitions("-D__USE_MINGW_ANSI_STDIO=1")
+
 # Find packages needed to build library
 find_package(libusb-1.0 REQUIRED)
 include_directories(${LIBUSB_1_INCLUDE_DIRS})
diff --git a/src/am7xxx.c b/src/am7xxx.c
index 51bce40..4bf9abb 100644
--- a/src/am7xxx.c
+++ b/src/am7xxx.c
@@ -38,6 +38,16 @@
 	#define  __attribute__(x)  /* NOTHING */
 #endif
 
+/*
+ * Fix printf format when compiling for Windows with MinGW, see:
+ * https://sourceforge.net/p/mingw-w64/wiki2/gnu%20printf/
+ */
+#ifdef __MINGW_PRINTF_FORMAT
+	#define AM7XXX_PRINTF_FORMAT __MINGW_PRINTF_FORMAT
+#else
+	#define AM7XXX_PRINTF_FORMAT printf
+#endif
+
 /* Control shared library symbols visibility */
 #if defined _WIN32 || defined __CYGWIN__
 	#define AM7XXX_PUBLIC __declspec(dllexport)
@@ -57,7 +67,7 @@ static void log_message(am7xxx_context *ctx,
 			const char *function_name,
 			int line,
 			const char *fmt,
-			...) __attribute__ ((format (printf, 5, 6)));
+			...) __attribute__ ((format (AM7XXX_PRINTF_FORMAT, 5, 6)));
 
 #define fatal(...)        log_message(NULL, AM7XXX_LOG_FATAL,   __func__, __LINE__, __VA_ARGS__)
 #define error(ctx, ...)   log_message(ctx,  AM7XXX_LOG_ERROR,   __func__, __LINE__, __VA_ARGS__)