[pygobject] setup.py: rework pycairo header lookup and use new pycairo API when available. See #150

[Christoph Reiter <creiter src gnome org>]

commit a153be8a6d79f52f1a45e2241e1fca5bd0aba6ea
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Mon Feb 5 10:49:55 2018 +0100

    setup.py: rework pycairo header lookup and use new pycairo API when available. See #150
    
    pycairo git/next version now has a get_include() function which gives us the
    include path matching the Python module in all cases.
    
    Rework the lookup code to try that API if possible and fall back to the old
    way. Also add logging everywhere so it's easier to debug if there is still
    something wrong.

 setup.py | 132 ++++++++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 88 insertions(+), 44 deletions(-)
---
diff --git a/setup.py b/setup.py
index 5d621f51..44d65149 100755
--- a/setup.py
+++ b/setup.py
@@ -133,19 +133,6 @@ def pkg_config_parse(opt, pkg):
     return [x.lstrip(opt) for x in output.split()]
 
 
-def samefile(src, dst):
-    # Python 2 on Windows doesn't have os.path.samefile, so we have to provide
-    # a fallback
-
-    if hasattr(os.path, "samefile"):
-        return os.path.samefile(src, dst)
-
-    os.stat(src)
-    os.stat(dst)
-    return (os.path.normcase(os.path.abspath(src)) ==
-            os.path.normcase(os.path.abspath(dst)))
-
-
 du_sdist = get_command_class("sdist")
 
 
@@ -495,32 +482,99 @@ def get_script_dir():
 
 def get_pycairo_include_dir():
     """Returns the best guess at where to find the pycairo headers.
+    A bit convoluted because we have to deal with multiple pycairo
+    versions.
 
-    Raises if pycairo isn't found.
+    Raises if pycairo isn't found or it's too old.
     """
 
     script_dir = get_script_dir()
-    min_version = get_version_requirement(
-        script_dir, get_pycairo_pkg_config_name())
-
-    dist = pkg_resources.get_distribution("pycairo>=%s" % min_version)
-    log.info("pycairo: found %r" % dist)
-
-    def get_sys_path(dist, name):
-        """The sysconfig path for a distribution, or None"""
+    pkg_config_name = get_pycairo_pkg_config_name()
+    min_version = get_version_requirement(script_dir, pkg_config_name)
 
-        location = dist.location
-        for scheme in sysconfig.get_scheme_names():
-            for path_type in ["platlib", "purelib"]:
-                path = sysconfig.get_path(path_type, scheme)
-                try:
-                    if samefile(path, location):
-                        return sysconfig.get_path(name, scheme)
-                except EnvironmentError:
-                    pass
+    def check_path(include_dir):
+        log.info("pycairo: trying include directory: %r" % include_dir)
+        header_path = os.path.join(include_dir, "%s.h" % pkg_config_name)
+        if os.path.exists(header_path):
+            log.info("pycairo: found %r" % header_path)
+            return True
+        log.info("pycairo: header file (%r) not found" % header_path)
+        return False
+
+    def find_path(paths):
+        for p in reversed(paths):
+            if check_path(p):
+                return p
+
+    def find_new_api():
+        log.info("pycairo: new API")
+        import cairo
+
+        pkg_version = pkg_resources.parse_version(cairo.version)
+        pkg_min_version = pkg_resources.parse_version(min_version)
+        if pkg_version < pkg_min_version:
+            raise DistutilsSetupError(
+                "pycairo >=%s required, %s found." % (
+                    pkg_min_version, pkg_version))
+
+        if hasattr(cairo, "get_include"):
+            return [cairo.get_include()]
+        log.info("pycairo: no get_include()")
+        return []
 
-    data_path = get_sys_path(dist, "data") or sys.prefix
-    return os.path.join(data_path, "include", "pycairo")
+    def find_old_api():
+        log.info("pycairo: old API")
+        dist = pkg_resources.get_distribution("pycairo>=%s" % min_version)
+        log.info("pycairo: found %r" % dist)
+
+        def samefile(src, dst):
+            # Python 2 on Windows doesn't have os.path.samefile, so we have to
+            # provide a fallback
+            if hasattr(os.path, "samefile"):
+                return os.path.samefile(src, dst)
+            os.stat(src)
+            os.stat(dst)
+            return (os.path.normcase(os.path.abspath(src)) ==
+                    os.path.normcase(os.path.abspath(dst)))
+
+        def get_sys_path(dist, name):
+            # Returns the sysconfig path for a distribution, or None
+            location = dist.location
+            for scheme in sysconfig.get_scheme_names():
+                for path_type in ["platlib", "purelib"]:
+                    path = sysconfig.get_path(path_type, scheme)
+                    try:
+                        if samefile(path, location):
+                            return sysconfig.get_path(name, scheme)
+                    except EnvironmentError:
+                        pass
+
+        data_path = get_sys_path(dist, "data") or sys.prefix
+        return [os.path.join(data_path, "include", "pycairo")]
+
+    def find_pkg_config():
+        log.info("pycairo: pkg-config")
+        pkg_config_version_check(pkg_config_name, min_version)
+        return pkg_config_parse("--cflags-only-I", pkg_config_name)
+
+    # First the new get_include() API added in >1.15.6
+    include_dir = find_path(find_new_api())
+    if include_dir is not None:
+        return include_dir
+
+    # Then try to find it in the data prefix based on the module path.
+    # This works with many virtualenv/userdir setups, but not all apparently,
+    # see https://gitlab.gnome.org/GNOME/pygobject/issues/150
+    include_dir = find_path(find_old_api())
+    if include_dir is not None:
+        return include_dir
+
+    # Finally, fall back to pkg-config
+    include_dir = find_path(find_pkg_config())
+    if include_dir is not None:
+        return include_dir
+
+    raise DistutilsSetupError("Could not find pycairo headers")
 
 
 def add_ext_pkg_config_dep(ext, compiler_type, name):
@@ -587,17 +641,7 @@ class build_ext(du_build_ext):
             add_ext_pkg_config_dep(ext, self.compiler_type, name)
 
         def add_pycairo(ext):
-            include_dir = get_pycairo_include_dir()
-
-            log.info("pycairo: using include directory: %r" % include_dir)
-            header_path = os.path.join(
-                include_dir, "%s.h" % get_pycairo_pkg_config_name())
-            if not os.path.exists(header_path):
-                raise DistutilsSetupError(
-                    "pycairo: header file (%r) not found" % header_path)
-            log.info("pycairo: found %r" % header_path)
-
-            ext.include_dirs += [include_dir]
+            ext.include_dirs += [get_pycairo_include_dir()]
 
         gi_ext = ext["gi._gi"]
         add_dependency(gi_ext, "glib-2.0")