[PATCH] libstdc++: Fix freestanding build PR 92376)

[Jonathan Wakely]

In a freestanding library we don't install the <pstl/pstl_config.h>
header, so don't try to include it unless it exists.

Explicitly declare aligned alloc functions for freestanding, because
<cstdlib> doesn't declare them.

        PR libstdc++/92376
        * include/bits/c++config: Only do PSTL config when the header is
        present, to fix freestanding.
        * libsupc++/new_opa.cc [!_GLIBCXX_HOSTED]: Declare allocation
        functions if they were detected by configure.

Tested powerpc64le-linux, committed to trunk.

This needs to be backported too.


commit 0ba6a850b597236832140bf57bf6083b6fab93f9
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Fri Jan 17 15:49:02 2020 +0000

    libstdc++: Fix freestanding build PR 92376)
    
    In a freestanding library we don't install the <pstl/pstl_config.h>
    header, so don't try to include it unless it exists.
    
    Explicitly declare aligned alloc functions for freestanding, because
    <cstdlib> doesn't declare them.
    
            PR libstdc++/92376
            * include/bits/c++config: Only do PSTL config when the header is
            present, to fix freestanding.
            * libsupc++/new_opa.cc [!_GLIBCXX_HOSTED]: Declare allocation
            functions if they were detected by configure.

diff --git a/libstdc++-v3/include/bits/c++config 
b/libstdc++-v3/include/bits/c++config
index 875a5e76890..b1fad59d4b3 100644
--- a/libstdc++-v3/include/bits/c++config
+++ b/libstdc++-v3/include/bits/c++config
@@ -666,6 +666,8 @@ namespace std
 // PSTL configuration
 
 #if __cplusplus >= 201703L
+// This header is not installed for freestanding:
+#if __has_include(<pstl/pstl_config.h>)
 // Preserved here so we have some idea which version of upstream we've pulled 
in
 // #define PSTL_VERSION 9000
 
@@ -684,6 +686,7 @@ namespace std
 # define _PSTL_ASSERT_MSG(_Condition, _Message) __glibcxx_assert(_Condition)
 
 #include <pstl/pstl_config.h>
+#endif // __has_include
+#endif // C++17
 
-#endif
 // End of prewritten config; the settings discovered at configure time follow.
diff --git a/libstdc++-v3/libsupc++/new_opa.cc 
b/libstdc++-v3/libsupc++/new_opa.cc
index 4e36fbf589d..8fac193cc7e 100644
--- a/libstdc++-v3/libsupc++/new_opa.cc
+++ b/libstdc++-v3/libsupc++/new_opa.cc
@@ -43,6 +43,21 @@ extern "C" void *memalign(std::size_t boundary, std::size_t 
size);
 using std::new_handler;
 using std::bad_alloc;
 
+#if ! _GLIBCXX_HOSTED
+extern "C"
+{
+# if _GLIBCXX_HAVE_ALIGNED_ALLOC
+  void *aligned_alloc(size_t alignment, size_t size);
+# elif _GLIBCXX_HAVE__ALIGNED_MALLOC
+  void *_aligned_malloc(size_t size, size_t alignment);
+# elif _GLIBCXX_HAVE_POSIX_MEMALIGN
+  void *posix_memalign(void **, size_t alignment, size_t size);
+# elif _GLIBCXX_HAVE_MEMALIGN
+  void *memalign(size_t alignment, size_t size);
+# endif
+}
+#endif
+
 namespace __gnu_cxx {
 #if _GLIBCXX_HAVE_ALIGNED_ALLOC
 using ::aligned_alloc;