[PATCH 0/1] Fix some warnings in the public headers

Hi all:

I am experimenting with Newlib and I am not using option -isystem <path>, but the normal -I<path>, so I get to see more compilation warnings than usual.

Maybe I am seeing more warnings because I am building in C++ mode.

I have prepared a patch to fix those warnings, see below. Notes about the patch are:

About __ARM_FP:

The documentation for __ARM_FP states "Set if hardware floating-point is available", so I was getting an "is not defined, evaluates to 0 [-Wundef]" warning.


About _FORTIFY_SOURCE:

The GCC manual states "when the _FORTIFY_SOURCE macro is defined to a non-zero value", and that symbol was not defined in my build, so I was getting an "is not defined, evaluates to 0 [-Wundef]" warning.


About __assert_func():

I was getting this warning:

redundant redeclaration of 'void __assert_func(const char*, int, const char*, const char*)' in same scope [-Wredundant-decls]


About __STDC_VERSION__:

I was getting an "is not defined, evaluates to 0 [-Wundef]" warning when compiling in C++ mode.


About _sig_func:

I was getting this warning:

 warning: unnecessary parentheses in declaration of '_sig_func' [-Wparentheses]
 

Thanks in advance,
  rdiez


R. Diez (1):
  Fix some compilation warnings.

 newlib/libc/include/assert.h         | 5 ++++-
 newlib/libc/include/machine/ieeefp.h | 2 +-
 newlib/libc/include/sys/features.h   | 2 +-
 newlib/libc/include/sys/reent.h      | 4 ++--
 4 files changed, 8 insertions(+), 5 deletions(-)

-- 
2.31.1

From dfb65e9d0b3e3335318e3cf85828ea4a14e252f0 Mon Sep 17 00:00:00 2001
From: "R. Diez" <[email protected]>
Date: Sun, 11 Apr 2021 11:48:02 +0200
Subject: [PATCH 1/1] Fix some compilation warnings.

Signed-off-by: R. Diez <[email protected]>
---
 newlib/libc/include/assert.h         | 5 ++++-
 newlib/libc/include/machine/ieeefp.h | 2 +-
 newlib/libc/include/sys/features.h   | 2 +-
 newlib/libc/include/sys/reent.h      | 4 ++--
 4 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/newlib/libc/include/assert.h b/newlib/libc/include/assert.h
index b9e5e9b4a..a15e7fbae 100644
--- a/newlib/libc/include/assert.h
+++ b/newlib/libc/include/assert.h
@@ -36,12 +36,15 @@ extern "C" {
 # endif /* !__ASSERT_FUNC */
 #endif /* !NDEBUG */
 
+#ifndef __ASSERT_WAS_DECLARED  /* Prevent "redundant redeclaration" warning when including this file multiple times. */
+#define __ASSERT_WAS_DECLARED
 void __assert (const char *, int, const char *)
 	    _ATTRIBUTE ((__noreturn__));
 void __assert_func (const char *, int, const char *, const char *)
 	    _ATTRIBUTE ((__noreturn__));
+#endif /* #ifndef __ASSERT_WAS_DECLARED */
 
-#if __STDC_VERSION__ >= 201112L && !defined __cplusplus
+#if !defined __cplusplus && __STDC_VERSION__ >= 201112L
 # define static_assert _Static_assert
 #endif
 
diff --git a/newlib/libc/include/machine/ieeefp.h b/newlib/libc/include/machine/ieeefp.h
index 3c1f41e03..37f7661cb 100644
--- a/newlib/libc/include/machine/ieeefp.h
+++ b/newlib/libc/include/machine/ieeefp.h
@@ -78,7 +78,7 @@
 # else
 #  define __IEEE_BIG_ENDIAN
 # endif
-# if __ARM_FP & 0x8
+# if defined(__ARM_FP) && (__ARM_FP & 0x8)
 #  define __OBSOLETE_MATH_DEFAULT 0
 # endif
 #else
diff --git a/newlib/libc/include/sys/features.h b/newlib/libc/include/sys/features.h
index 218807178..65f5af763 100644
--- a/newlib/libc/include/sys/features.h
+++ b/newlib/libc/include/sys/features.h
@@ -319,7 +319,7 @@ extern "C" {
 #define	__XSI_VISIBLE		0
 #endif
 
-#if _FORTIFY_SOURCE > 0 && !defined(__cplusplus) && !defined(__lint__) && \
+#if defined(_FORTIFY_SOURCE) && _FORTIFY_SOURCE > 0 && !defined(__cplusplus) && !defined(__lint__) && \
    (__OPTIMIZE__ > 0 || defined(__clang__)) && __GNUC_PREREQ__(4, 1)
 #  if _FORTIFY_SOURCE > 1
 #    define __SSP_FORTIFY_LEVEL 2
diff --git a/newlib/libc/include/sys/reent.h b/newlib/libc/include/sys/reent.h
index 74b70e9c0..f62e5817b 100644
--- a/newlib/libc/include/sys/reent.h
+++ b/newlib/libc/include/sys/reent.h
@@ -409,7 +409,7 @@ struct _reent
   char *_asctime_buf;
 
   /* signal info */
-  void (**(_sig_func))(int);
+  void (**_sig_func)(int);
 
 # ifndef _REENT_GLOBAL_ATEXIT
   /* atexit stuff */
@@ -682,7 +682,7 @@ struct _reent
 # endif
 
   /* signal info */
-  void (**(_sig_func))(int);
+  void (**_sig_func)(int);
 
   /* These are here last so that __FILE can grow without changing the offsets
      of the above members (on the off chance that future binary compatibility
-- 
2.31.1