GDL: python integration fixes (#9936)

* GDL: python integration fixes

* renamed python-related variants to follow the convention
* building the Python module requires patches currently targetting 0.9.8 othwerwise asking for the Python module *only* builds the Pyhton module
* building the python module also requires patching the vendored (with the GDL) antlr to be built as a shared library

* Typo

Co-Authored-By: rmsds <ricardo.d.silva@gmail.com>

* Rename embed-python variant to embed_python

var/spack/repos/builtin/packages/gdl/Always-build-antlr-as-shared-library.patch

@@ -0,0 +1,27 @@
+From: Ricardo Silva <ricardo.silva@epfl.ch>
+Date: Wed, 3 Oct 2018 13:42:25 +0200
+Subject: [PATCH] Always build antlr as shared library
+
+---
+ src/antlr/CMakeLists.txt | 8 ++------
+ 1 file changed, 2 insertions(+), 6 deletions(-)
+
+diff --git a/src/antlr/CMakeLists.txt b/src/antlr/CMakeLists.txt
+index 26a38e3..083e50d 100644
+--- a/src/antlr/CMakeLists.txt
++++ b/src/antlr/CMakeLists.txt
+@@ -2,9 +2,5 @@ aux_source_directory(${CMAKE_CURRENT_SOURCE_DIR} ANTLRSOURCES)
+ list(REMOVE_ITEM ANTLRSOURCES ${CMAKE_CURRENT_SOURCE_DIR}/dll.cpp)
+ include_directories(${CMAKE_SOURCE_DIR} ${CMAKE_SOURCE_DIR}/src/antlr)
+ 
+-if(PYTHON_MODULE)
+-	add_library(antlr SHARED ${ANTLRSOURCES})
+-	install(TARGETS antlr DESTINATION ${CMAKE_INSTALL_PREFIX}/lib)
+-else(PYTHON_MODULE)
+-	add_library(antlr STATIC ${ANTLRSOURCES})
+-endif(PYTHON_MODULE)
++add_library(antlr SHARED ${ANTLRSOURCES})
++install(TARGETS antlr DESTINATION ${CMAKE_INSTALL_PREFIX}/lib)
+-- 
+1.8.3.1
+

var/spack/repos/builtin/packages/gdl/package.py

@@ -2,7 +2,7 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
+import os
 from spack import *
 
 
@@ -27,7 +27,8 @@ class Gdl(CMakePackage):
     variant('hdf5', default=True, description='Enable HDF5')
     variant('openmp', default=True, description='Enable OpenMP')
     variant('proj', default=True, description='Enable LIBPROJ4')
-    variant('python', default=False, description='Enable Python')
+    variant('embed_python', default=False, description='Ability to embed Python within GDL')
+    variant('python', default=False, description='Build the GDL Python module')
     variant('wx', default=False, description='Enable WxWidgets')
     variant('x11', default=False, description='Enable X11')
 
@@ -41,8 +42,8 @@ class Gdl(CMakePackage):
     depends_on('plplot+wx+wxold', when='+wx@5.12:')
     depends_on('plplot~wx', when='~wx')
     depends_on('proj', when='+proj')
-    depends_on('py-numpy', type=('build', 'run'), when='+python')
-    depends_on('python@2.7:2.8', type=('build', 'run'), when='+python')
+    depends_on('py-numpy', type=('build', 'run'), when='+embed_python')
+    depends_on('python@2.7:2.8', type=('build', 'run'), when='+embed_python')
     depends_on('wx', when='+wx')
 
     depends_on('eigen')
@@ -57,6 +58,21 @@ class Gdl(CMakePackage):
     depends_on('pslib')
     depends_on('readline')
 
+    conflicts('+python', when='~embed_python')
+
+    # Building the Python module requires patches currently targetting 0.9.8
+    # othwerwise asking for the Python module *only* builds the Python module
+    conflicts('+python', when='@:0.9.7,0.9.9:')
+
+    # Allows building gdl as a shared library to in turn allow building
+    # both the executable and the Python module
+    patch('https://sources.debian.org/data/main/g/gnudatalanguage/0.9.8-7/debian/patches/Create-a-shared-library.patch',
+          sha256='bb380394c8ea2602404d8cd18047b93cf00fdb73b83d389f30100dd4b0e1a05c',
+          when='@0.9.8')
+    patch('Always-build-antlr-as-shared-library.patch',
+          sha256='f40c06e8a8f1977780787f58885590affd7e382007cb677d2fb4723aaadd415c',
+          when='@0.9.8')
+
     def cmake_args(self):
         args = []
 
@@ -92,11 +108,16 @@ def cmake_args(self):
         else:
             args += ['-DLIBPROJ4=OFF']
 
-        if '+python' in self.spec:
+        if '+embed_python' in self.spec:
             args += ['-DPYTHON=ON']
         else:
             args += ['-DPYTHON=OFF']
 
+        if '+python' in self.spec:
+            args += ['-DPYTHON_MODULE=ON']
+        else:
+            args += ['-DPYTHON_MODULE=OFF']
+
         if '+wx' in self.spec:
             args += ['-DWXWIDGETS=ON']
         else:
@@ -108,3 +129,19 @@ def cmake_args(self):
             args += ['-DX11=OFF']
 
         return args
+
+    @run_after('install')
+    def post_install(self):
+        if '+python' in self.spec:
+            # gdl installs the python module into prefix/lib/site-python
+            # move it to the standard location
+            src = os.path.join(
+                self.spec.prefix.lib,
+                'site-python')
+            dst = site_packages_dir
+            if os.path.isdir(src):
+                if not os.path.isdir(dst):
+                    mkdirp(dst)
+                for f in os.listdir(src):
+                    os.rename(os.path.join(src, f),
+                              os.path.join(dst, f))