runtests: include the C compiler error output in the compile exception to show...

runtests: include the C compiler error output in the compile exception to show it at the end of the test run.

Cython/Build/IpythonMagic.py

@@ -82,7 +82,7 @@ from ..Shadow import __version__ as cython_version
 from ..Compiler.Errors import CompileError
 from .Inline import cython_inline
 from .Dependencies import cythonize
-from ..Utils import captured_fd
+from ..Utils import captured_fd, print_captured
 
 
 PGO_CONFIG = {
@@ -107,37 +107,6 @@ else:
         return name
 
 
-def get_encoding_candidates():
-    candidates = [sys.getdefaultencoding()]
-    for stream in (sys.stdout, sys.stdin, sys.__stdout__, sys.__stdin__):
-        encoding = getattr(stream, 'encoding', None)
-        # encoding might be None (e.g. somebody redirects stdout):
-        if encoding is not None and encoding not in candidates:
-            candidates.append(encoding)
-    return candidates
-
-
-def prepare_captured(captured):
-    captured_bytes = captured.strip()
-    if not captured_bytes:
-        return None
-    for encoding in get_encoding_candidates():
-        try:
-            return captured_bytes.decode(encoding)
-        except UnicodeDecodeError:
-            pass
-    # last resort: print at least the readable ascii parts correctly.
-    return captured_bytes.decode('latin-1')
-
-
-def print_captured(captured, output, header_line=None):
-    captured = prepare_captured(captured)
-    if captured:
-        if header_line:
-            output.write(header_line)
-        output.write(captured)
-
-
 @magics_class
 class CythonMagics(Magics):
 

Cython/Utils.py

@@ -443,6 +443,37 @@ def captured_fd(stream=2, encoding=None):
         os.close(orig_stream)
 
 
+def get_encoding_candidates():
+    candidates = [sys.getdefaultencoding()]
+    for stream in (sys.stdout, sys.stdin, sys.__stdout__, sys.__stdin__):
+        encoding = getattr(stream, 'encoding', None)
+        # encoding might be None (e.g. somebody redirects stdout):
+        if encoding is not None and encoding not in candidates:
+            candidates.append(encoding)
+    return candidates
+
+
+def prepare_captured(captured):
+    captured_bytes = captured.strip()
+    if not captured_bytes:
+        return None
+    for encoding in get_encoding_candidates():
+        try:
+            return captured_bytes.decode(encoding)
+        except UnicodeDecodeError:
+            pass
+    # last resort: print at least the readable ascii parts correctly.
+    return captured_bytes.decode('latin-1')
+
+
+def print_captured(captured, output, header_line=None):
+    captured = prepare_captured(captured)
+    if captured:
+        if header_line:
+            output.write(header_line)
+        output.write(captured)
+
+
 def print_bytes(s, header_text=None, end=b'\n', file=sys.stdout, flush=True):
     if header_text:
         file.write(header_text)  # note: text! => file.write() instead of out.write()

runtests.py

@@ -1277,10 +1277,25 @@ class CythonCompileTestCase(unittest.TestCase):
                 extension.language = 'c++'
             if IS_PY2:
                 workdir = str(workdir)  # work around type check in distutils that disallows unicode strings
+
             build_extension.extensions = [extension]
             build_extension.build_temp = workdir
             build_extension.build_lib  = workdir
-            build_extension.run()
+
+            from Cython.Utils import captured_fd, prepare_captured
+            from distutils.errors import CompileError
+
+            error = None
+            with captured_fd(2) as get_stderr:
+                try:
+                    build_extension.run()
+                except CompileError as exc:
+                    error = exc
+            stderr = prepare_captured(get_stderr())
+            if stderr:
+                print("Compiler output for module %s:\n%s" % (module, stderr))
+            if error is not None:
+                raise CompileError("%s\nCompiler output:\n%s" % (error, stderr))
         finally:
             os.chdir(cwd)