cbprintf: Remove support for toolchains without _Generic

As part of the transition from C99 to C17 as the minimum supported C
standard version, remove the workarounds in the formatted output
subsystem to maintain compatibility with toolchains that do not support
the _Generic keyword.

Signed-off-by: Carles Cufi <[email protected]>

Author: carlescufi

doc/services/formatted_output.rst

@@ -81,9 +81,8 @@ Package can be created using two methods:
   package.
 * static - types of arguments are detected at compile time by the preprocessor
   and package is created as simple assignments to a provided memory. This method
-  is significantly faster than runtime (more than 15 times) but has following
-  limitations: requires ``_Generic`` keyword (C11 feature) to be supported by
-  the compiler and cannot distinguish between ``%p`` and ``%s`` if char pointer
+  is significantly faster than runtime (more than 15 times) but has a
+  significant limitation: it cannot distinguish between ``%p`` and ``%s`` if char pointer
   is used. It treats all (unsigned) char pointers as ``%s`` thus it will attempt
   to append string to a package. It can be handled correctly during conversion
   from **transient** package to **self-contained** package using
@@ -174,7 +173,6 @@ formatting since address changes whenever package is copied.
 Limitations and recommendations
 ===============================
 
-* C11 ``_Generic`` support is required by the compiler to use static (fast) packaging.
 * It is recommended to cast any character pointer used with ``%p`` format specifier to
   other pointer type (e.g. ``void *``). If format string is not accessible then only
   static packaging is possible and it will append all detected strings. Character pointer

doc/services/logging/index.rst

@@ -869,8 +869,6 @@ The are following recommendations:
 
 * Enable :kconfig:option:`CONFIG_LOG_SPEED` to slightly speed up deferred logging at the
   cost of slight increase in memory footprint.
-* Compiler with C11 ``_Generic`` keyword support is recommended. Logging
-  performance is significantly degraded without it. See :ref:`cbprintf_packaging`.
 * It is recommended to cast pointer to ``const char *`` when it is used with ``%s``
   format specifier and it points to a constant string.
 * It is recommended to cast pointer to ``char *`` when it is used with ``%s``

include/zephyr/sys/cbprintf.h

@@ -17,19 +17,6 @@
 #include <stdio.h>
 #endif /* CONFIG_CBPRINTF_LIBC_SUBSTS */
 
-/* Determine if _Generic is supported using macro from toolchain.h.
- *
- * @note Z_C_GENERIC is also set for C++ where functionality is implemented
- * using overloading and templates.
- */
-#ifndef Z_C_GENERIC
-#if defined(__cplusplus) || TOOLCHAIN_HAS_C_GENERIC
-#define Z_C_GENERIC 1
-#else
-#define Z_C_GENERIC 0
-#endif
-#endif
-
 #ifdef __xtensa__
 #define Z_PKG_HDR_EXT_XTENSA_ALIGNMENT 8
 #ifdef CONFIG_CBPRINTF_PACKAGE_HEADER_STORE_CREATION_FLAGS
@@ -120,7 +107,6 @@ BUILD_ASSERT(sizeof(struct cbprintf_package_hdr_ext) % Z_PKG_HDR_EXT_XTENSA_ALIG
  * @endcond
  */
 
-/* Z_C_GENERIC is used there */
 #include <zephyr/sys/cbprintf_internal.h>
 
 #ifdef __cplusplus

include/zephyr/sys/cbprintf_internal.h

@@ -534,7 +534,6 @@ extern "C" {
  * @retval 1 if string must be packaged at runtime.
  * @retval 0 if string can be statically packaged.
  */
-#if Z_C_GENERIC
 #define Z_CBPRINTF_MUST_RUNTIME_PACKAGE(flags, ...) ({\
 	int _rv; \
 	if ((flags) & CBPRINTF_PACKAGE_ADD_RW_STR_POS) { \
@@ -544,9 +543,6 @@ extern "C" {
 	} \
 	_rv; \
 })
-#else
-#define Z_CBPRINTF_MUST_RUNTIME_PACKAGE(flags, ...) 1
-#endif
 
 /** @brief Get storage size for given argument.
  *
@@ -864,23 +860,10 @@ do { \
 	} \
 } while (false)
 
-#if Z_C_GENERIC
 #define Z_CBPRINTF_STATIC_PACKAGE(packaged, inlen, outlen, align_offset, flags, \
 				  ... /* fmt, ... */) \
 	Z_CBPRINTF_STATIC_PACKAGE_GENERIC(packaged, inlen, outlen, \
 					  align_offset, flags, __VA_ARGS__)
-#else
-#define Z_CBPRINTF_STATIC_PACKAGE(packaged, inlen, outlen, align_offset, flags, \
-				  ... /* fmt, ... */) \
-do { \
-	/* Small trick needed to avoid warning on always true */ \
-	if (((uintptr_t)packaged + 1) != 1) { \
-		outlen = cbprintf_package(packaged, inlen, flags, __VA_ARGS__); \
-	} else { \
-		outlen = cbprintf_package(NULL, align_offset, flags, __VA_ARGS__); \
-	} \
-} while (false)
-#endif /* Z_C_GENERIC */
 
 #ifdef __cplusplus
 }

lib/os/cbprintf_packaged.c

@@ -17,12 +17,6 @@
 #include <zephyr/logging/log.h>
 LOG_MODULE_REGISTER(cbprintf_package, CONFIG_CBPRINTF_PACKAGE_LOG_LEVEL);
 
-#if defined(CONFIG_CBPRINTF_PACKAGE_SUPPORT_TAGGED_ARGUMENTS) && \
-	!Z_C_GENERIC
-#error "CONFIG_CBPRINTF_PACKAGE_SUPPORT_TAGGED_ARGUMENTS " \
-	"requires toolchain to support _Generic!"
-#endif
-
 /**
  * @brief Check if address is in read only section.
  *

tests/lib/cbprintf_package/src/main.c

@@ -59,7 +59,6 @@ static void unpack(const char *desc, struct out_buffer *buf,
 
 #define TEST_PACKAGING(flags, fmt, ...) do { \
 	int must_runtime = CBPRINTF_MUST_RUNTIME_PACKAGE(flags, fmt, __VA_ARGS__); \
-	zassert_equal(must_runtime, !Z_C_GENERIC); \
 	snprintfcb(compare_buf, sizeof(compare_buf), fmt, __VA_ARGS__); \
 	printk("-----------------------------------------\n"); \
 	printk("%s\n", compare_buf); \
@@ -683,14 +682,6 @@ ZTEST(cbprintf_package, test_cbprintf_ro_rw_loc_const_char_ptr)
 
 static void cbprintf_rw_loc_const_char_ptr(bool keep_ro_str)
 {
-	/* Test requires that static packaging is applied. Runtime packaging
-	 * cannot be tricked because it checks pointers against read only
-	 * section.
-	 */
-	if (Z_C_GENERIC == 0) {
-		ztest_test_skip();
-	}
-
 	int slen, slen2;
 	int clen, clen2;
 	static const char test_str[] = "test %s %d %s";
@@ -778,10 +769,6 @@ ZTEST(cbprintf_package, test_cbprintf_must_runtime_package)
 {
 	int rv;
 
-	if (Z_C_GENERIC == 0) {
-		ztest_test_skip();
-	}
-
 	rv = CBPRINTF_MUST_RUNTIME_PACKAGE(0, "test");
 	zassert_equal(rv, 0);
 
@@ -1006,7 +993,6 @@ static void *print_size_and_alignment_info(void)
 	printk("alignof: int=%zu long=%zu ptr=%zu long long=%zu double=%zu long double=%zu\n",
 	       __alignof__(int), __alignof__(long), __alignof__(void *), __alignof__(long long),
 	       __alignof__(double), __alignof__(long double));
-	printk("%s C11 _Generic\n", Z_C_GENERIC ? "With" : "Without");
 #endif
 
 	return NULL;

tests/lib/cbprintf_package/testcase.yaml

@@ -11,13 +11,6 @@ tests:
     integration_platforms:
       - native_sim
 
-  libraries.cbprintf.package_no_generic:
-    extra_configs:
-      - CONFIG_CBPRINTF_COMPLETE=y
-      - CONFIG_COMPILER_OPT="-DZ_C_GENERIC=0"
-    integration_platforms:
-      - native_sim
-
   libraries.cbprintf.package_fp:
     filter: CONFIG_CPU_HAS_FPU
     extra_configs:
@@ -76,14 +69,6 @@ tests:
     integration_platforms:
       - native_sim
 
-  libraries.cbprintf.package_no_generic_cpp:
-    extra_configs:
-      - CONFIG_CPP=y
-      - CONFIG_CBPRINTF_COMPLETE=y
-      - CONFIG_COMPILER_OPT="-DZ_C_GENERIC=0"
-    integration_platforms:
-      - native_sim
-
   libraries.cbprintf.package_fp_cpp:
     filter: CONFIG_CPU_HAS_FPU
     extra_configs:
@@ -148,16 +133,6 @@ tests:
     integration_platforms:
       - qemu_x86
 
-  libraries.cbprintf.package_no_generic.picolibc:
-    filter: CONFIG_PICOLIBC_SUPPORTED
-    tags: picolibc
-    extra_configs:
-      - CONFIG_CBPRINTF_COMPLETE=y
-      - CONFIG_COMPILER_OPT="-DZ_C_GENERIC=0"
-      - CONFIG_PICOLIBC=y
-    integration_platforms:
-      - qemu_x86
-
   libraries.cbprintf.package_fp.picolibc:
     filter: CONFIG_CPU_HAS_FPU and CONFIG_PICOLIBC_SUPPORTED
     tags: picolibc
@@ -180,17 +155,6 @@ tests:
     integration_platforms:
       - qemu_x86
 
-  libraries.cbprintf.package_no_generic_cpp.picolibc:
-    filter: CONFIG_PICOLIBC_SUPPORTED
-    tags: picolibc
-    extra_configs:
-      - CONFIG_CPP=y
-      - CONFIG_CBPRINTF_COMPLETE=y
-      - CONFIG_COMPILER_OPT="-DZ_C_GENERIC=0"
-      - CONFIG_PICOLIBC=y
-    integration_platforms:
-      - qemu_x86
-
   libraries.cbprintf.package_fp_cpp.picolibc:
     filter: CONFIG_CPU_HAS_FPU and CONFIG_PICOLIBC_SUPPORTED
     tags: picolibc

tests/unit/cbprintf/main.c

@@ -35,9 +35,6 @@
 #else
 #define USE_PACKAGED 0
 #endif
-#if (VIA_TWISTER & 0x800) != 0
-#define AVOID_C_GENERIC 1
-#endif
 #if (VIA_TWISTER & 0x1000) != 0
 #define PKG_ALIGN_OFFSET sizeof(void *)
 #endif
@@ -63,10 +60,6 @@
 #define ENABLED_USE_PACKAGED false
 #endif
 
-#if AVOID_C_GENERIC
-#define Z_C_GENERIC 0
-#endif
-
 #ifndef PACKAGE_FLAGS
 #define PACKAGE_FLAGS 0
 #endif
@@ -1181,11 +1174,6 @@ ZTEST(prf, test_cbprintf_package_rw_string_indexes)
 		return;
 	}
 
-	if (!Z_C_GENERIC) {
-		/* runtime packaging will not detect ro strings. */
-		return;
-	}
-
 	int len0, len1;
 	static const char *test_str = "test %d %s";
 	static const char *test_str1 = "lorem ipsum";
@@ -1249,10 +1237,6 @@ ZTEST(prf, test_cbprintf_fsc_package)
 		return;
 	}
 
-	if (!Z_C_GENERIC) {
-		/* runtime packaging will not detect ro strings. */
-		return;
-	}
 
 	char test_str[] = "test %d %s";
 	const char *test_str1 = "lorem ipsum";
@@ -1449,8 +1433,7 @@ static void *cbprintf_setup(void)
 		TC_PRINT(" NANO\n");
 	}
 	if (ENABLED_USE_PACKAGED) {
-		TC_PRINT(" PACKAGED %s C11 _Generic\n",
-				Z_C_GENERIC ? "with" : "without");
+		TC_PRINT(" PACKAGED\n");
 	} else {
 		TC_PRINT(" VA_LIST\n");
 	}