bpo-35198 Fix C++ extension compilation on AIX (GH-10437)

For C++ extensions, distutils tries to replace the C compiler with the
C++ compiler, but it assumes that C compiler is the first element after
any environment variables set. On AIX, linking goes through ld_so_aix,
so it is the first element and the compiler is the next element. Thus
the replacement is faulty:

ld_so_aix gcc ... -> g++ gcc ...

Also, it assumed that self.compiler_cxx had only 1 element or that
there were the same number of elements as the linker has and in the
same order. This might not be the case, so instead concatenate
everything together.

2 files changed, 10 insertions, 1 deletions

diff --git a/Lib/distutils/unixccompiler.py b/Lib/distutils/unixccompiler.py
index ab4d4de..d10a78d 100644
--- a/Lib/distutils/unixccompiler.py
+++ b/Lib/distutils/unixccompiler.py
@@ -188,7 +188,15 @@ class UnixCCompiler(CCompiler):
                         i = 1
                         while '=' in linker[i]:
                             i += 1
-                    linker[i] = self.compiler_cxx[i]
+
+                    if os.path.basename(linker[i]) == 'ld_so_aix':
+                        # AIX platforms prefix the compiler with the ld_so_aix
+                        # script, so we need to adjust our linker index
+                        offset = 1
+                    else:
+                        offset = 0
+
+                    linker[i+offset] = self.compiler_cxx[i]
 
                 if sys.platform == 'darwin':
                     linker = _osx_support.compiler_fixup(linker, ld_args)
diff --git a/Misc/NEWS.d/next/Library/2018-11-09-12-45-28.bpo-35198.EJ8keW.rst b/Misc/NEWS.d/next/Library/2018-11-09-12-45-28.bpo-35198.EJ8keW.rst
new file mode 100644
index 0000000..4ce7a7e
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-11-09-12-45-28.bpo-35198.EJ8keW.rst
@@ -0,0 +1 @@
+Fix C++ extension compilation on AIX