[gcc r11-10580] libstdc++: Horrible macro hacks to allow building on avr

[Jonathan Wakely <redi@gcc.gnu.org>]

https://gcc.gnu.org/g:061700c9f6f0f9f4219ddeb236d55764b42869b6

commit r11-10580-g061700c9f6f0f9f4219ddeb236d55764b42869b6
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Feb 2 18:03:26 2023 +0000

    libstdc++: Horrible macro hacks to allow building on avr
    
    In r12-4071-g59ffa3e3dba5a7 I added a new __unsupported() function and
    replaced all std::filesystem's uses of std::errc::not_supported and
    ENOTSUP with a call to that function. Then in r13-5664-g5c43f06c228d16
    that function was tweaked to use ENOSYS instead of EOPNOTSUP for avr,
    due to limitations of <errno.h> on avr-libc.
    
    In the gcc-11 branch we don't have __unsupported(), so we get loads and
    loads of failures when trying to compile the src/c++17/fs_*.cc files.
    This horrible hack uses macros to redefine not_supported and ENOTSUP as
    function_not_supported and ENOSYS respectively, to fix the build for
    avr.
    
    libstdc++-v3/ChangeLog:
    
            * src/c++17/fs_ops.cc [AVR] (not_supported): Define as a macro
            for function_not_supported.
            * src/filesystem/ops-common.h [AVR] (ENOTSUP): Define as a macro
            for ENOSYS.

Diff:
---
 libstdc++-v3/src/c++17/fs_ops.cc         | 4 ++++
 libstdc++-v3/src/filesystem/ops-common.h | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/libstdc++-v3/src/c++17/fs_ops.cc b/libstdc++-v3/src/c++17/fs_ops.cc
index 4155b4d64b9..802894ea5b5 100644
--- a/libstdc++-v3/src/c++17/fs_ops.cc
+++ b/libstdc++-v3/src/c++17/fs_ops.cc
@@ -61,6 +61,10 @@
 #define _GLIBCXX_END_NAMESPACE_FILESYSTEM }
 #include "../filesystem/ops-common.h"
 
+#ifdef __AVR__
+# define not_supported function_not_supported
+#endif
+
 #pragma GCC diagnostic ignored "-Wunused-parameter"
 
 namespace fs = std::filesystem;
diff --git a/libstdc++-v3/src/filesystem/ops-common.h b/libstdc++-v3/src/filesystem/ops-common.h
index 54bafff2a9c..a680a51c984 100644
--- a/libstdc++-v3/src/filesystem/ops-common.h
+++ b/libstdc++-v3/src/filesystem/ops-common.h
@@ -170,6 +170,10 @@ namespace __gnu_posix
 # endif
   using char_type = char;
 #else // ! _GLIBCXX_FILESYSTEM_IS_WINDOWS && ! _GLIBCXX_HAVE_UNISTD_H
+#ifdef __AVR__
+# define ENOTSUP ENOSYS
+#endif
+
   inline int open(const char*, int, ...) { errno = ENOTSUP; return -1; }
   inline int close(int) { errno = ENOTSUP; return -1; }
   using mode_t = int;