libs/libc: add limits checks

NuttX defines constants for the sizes of types just as constants
directly in the code. The real values depend on compiler and target
platform. It is possible that value declared by NuttX header is wrong
compared to the compiler configuration. This is more likely in case of
floating points.

Not all compilers supported by NuttX provide required info through
defines and thus it is more generic to specify limits as constants, but
in case compiler provides them then it is a good idea to compare. This
commit adds such set of comparisons for limits.h and float.h constants.

The comparisons were tested with GCC and Clang. They will be ignored in
case compiler doesn't provide them.

Signed-off-by: Karel Kočí <kkoci@elektroline.cz>

Author: Cynerd

libs/libc/Makefile

@@ -73,6 +73,8 @@ include wctype/Make.defs
 include wqueue/Make.defs
 include fdt/Make.defs
 
+CSRCS += limits_check.c
+
 # Use double delim to fix windows native build and give an error:
 # makefile:132: *** target mode do not include“%”. stop.
 #

libs/libc/limits_check.c

@@ -0,0 +1,195 @@
+/****************************************************************************
+ * libs/libc/limits_check.c
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/* NuttX prefers defining limits per architecture directly as constants
+ * instead of using compiler provided definitions. That is to support
+ * compilers that do not provide such definitions. On the other hand in case
+ * compiler provides these definitions we should not deviate from them. This
+ * file thus contains only checks of NuttX's defined limits against compiler
+ * definitions if available.
+ */
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <assert.h>
+
+#include <limits.h>
+#include <float.h>
+
+/****************************************************************************
+ * Pre-processor Prototypes
+ ****************************************************************************/
+
+#ifdef static_assert
+#  define static_assert_equal(COMPILER_DEF, DEF) \
+  static_assert(COMPILER_DEF == DEF, "Compiler definition mismatch for " #DEF)
+#else
+#  define DEFINITION_ASSERT(COMPILER_DEF, DEF)
+#endif
+
+#ifdef __CHAR_BIT__
+static_assert_equal(__CHAR_BIT__, CHAR_BIT);
+#endif
+
+#ifdef __SCHAR_MAX__
+static_assert_equal(__SCHAR_MAX__, SCHAR_MAX);
+#endif
+
+#ifdef __SHRT_MAX__
+static_assert_equal(__SHRT_MAX__, SHRT_MAX);
+#endif
+
+#ifdef __LONG_MAX__
+static_assert_equal(__LONG_MAX__, LONG_MAX);
+#endif
+
+#ifdef __LONG_LONG_MAX__
+static_assert_equal(__LONG_LONG_MAX__, LLONG_MAX);
+#endif
+
+#ifdef __UINTPTR_MAX__
+static_assert_equal(__UINTPTR_MAX__, UPTR_MAX);
+#endif
+
+#ifdef __WCHAR_MAX__
+static_assert_equal(__WCHAR_MAX__, WCHAR_MAX);
+#endif
+
+#ifdef __FLT_MANT_DIG__
+static_assert_equal(__FLT_MANT_DIG__, FLT_MANT_DIG);
+#endif
+
+#ifdef __DBL_MANT_DIG__
+static_assert_equal(__DBL_MANT_DIG__, DBL_MANT_DIG);
+#endif
+
+#ifdef __LDBL_MANT_DIG__
+static_assert_equal(__LDBL_MANT_DIG__, LDBL_MANT_DIG);
+#endif
+
+#ifdef __FLT_DIG__
+static_assert_equal(__FLT_DIG__, FLT_DIG);
+#endif
+
+#ifdef __DBL_DIG__
+static_assert_equal(__DBL_DIG__, DBL_DIG);
+#endif
+
+#ifdef __LDBL_DIG__
+static_assert_equal(__LDBL_DIG__, LDBL_DIG);
+#endif
+
+#ifdef __FLT_MIN_EXP__
+static_assert_equal(__FLT_MIN_EXP__, FLT_MIN_EXP);
+#endif
+
+#ifdef __DBL_MIN_EXP__
+static_assert_equal(__DBL_MIN_EXP__, DBL_MIN_EXP);
+#endif
+
+#ifdef __LDBL_MIN_EXP__
+static_assert_equal(__LDBL_MIN_EXP__, LDBL_MIN_EXP);
+#endif
+
+#ifdef __FLT_MIN_10_EXP__
+static_assert_equal(__FLT_MIN_10_EXP__, FLT_MIN_10_EXP);
+#endif
+
+#ifdef __DBL_MIN_10_EXP__
+static_assert_equal(__DBL_MIN_10_EXP__, DBL_MIN_10_EXP);
+#endif
+
+#ifdef __LDBL_MIN_10_EXP__
+static_assert_equal(__LDBL_MIN_10_EXP__, LDBL_MIN_10_EXP);
+#endif
+
+#ifdef __FLT_MAX_EXP__
+static_assert_equal(__FLT_MAX_EXP__, FLT_MAX_EXP);
+#endif
+
+#ifdef __DBL_MAX_EXP__
+static_assert_equal(__DBL_MAX_EXP__, DBL_MAX_EXP);
+#endif
+
+#ifdef __LDBL_MAX_EXP__
+static_assert_equal(__LDBL_MAX_EXP__, LDBL_MAX_EXP);
+#endif
+
+#ifdef __FLT_MAX_10_EXP__
+static_assert_equal(__FLT_MAX_10_EXP__, FLT_MAX_10_EXP);
+#endif
+
+#ifdef __DBL_MAX_10_EXP__
+static_assert_equal(__DBL_MAX_10_EXP__, DBL_MAX_10_EXP);
+#endif
+
+#ifdef __LDBL_MAX_10_EXP__
+static_assert_equal(__LDBL_MAX_10_EXP__, LDBL_MAX_10_EXP);
+#endif
+
+#ifdef __FLT_MAX__
+static_assert_equal(__FLT_MAX__, FLT_MAX);
+#endif
+
+#ifdef __DBL_MAX__
+static_assert_equal(__DBL_MAX__, DBL_MAX);
+#endif
+
+#ifdef __LDBL_MAX__
+static_assert_equal(__LDBL_MAX__, LDBL_MAX);
+#endif
+
+#ifdef __FLT_EPSILON__
+static_assert_equal(__FLT_EPSILON__, FLT_EPSILON);
+#endif
+
+#ifdef __DBL_EPSILON__
+static_assert_equal(__DBL_EPSILON__, DBL_EPSILON);
+#endif
+
+#ifdef __LDBL_EPSILON__
+static_assert_equal(__LDBL_EPSILON__, LDBL_EPSILON);
+#endif
+
+#ifdef __FLT_MIN__
+static_assert_equal(__FLT_MIN__, FLT_MIN);
+#endif
+
+#ifdef __DBL_MIN__
+static_assert_equal(__DBL_MIN__, DBL_MIN);
+#endif
+
+#ifdef __LDBL_MIN__
+static_assert_equal(__LDBL_MIN__, LDBL_MIN);
+#endif
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/