Evaluate always SCM attribute before exporting the recipe

conans/client/cmd/export.py

@@ -69,12 +69,17 @@ def _capture_export_scm_data(conanfile, conanfile_dir, destination_folder, outpu
         os.unlink(scm_src_file)
 
     scm_data = get_scm_data(conanfile)
-    captured_revision = scm_data.capture_revision if scm_data else False
+    if not scm_data:
+        return None, False
 
-    if not scm_data or not (scm_data.capture_origin or scm_data.capture_revision):
-        return None, captured_revision
+    # Resolve SCMData in the user workspace (someone may want to access CVS or import some py)
+    captured_revision = scm_data.capture_revision
 
     scm = SCM(scm_data, conanfile_dir, output)
+    if scm_data.capture_origin or scm_data.capture_revision:
+        # Generate the scm_folder.txt file pointing to the src_path
+        src_path = scm.get_repo_root()
+        save(scm_src_file, src_path.replace("\\", "/"))
 
     if scm_data.url == "auto":
         origin = scm.get_qualified_remote_url()
@@ -84,17 +89,14 @@ def _capture_export_scm_data(conanfile, conanfile_dir, destination_folder, outpu
             output.warn("Repo origin looks like a local path: %s" % origin)
         output.success("Repo origin deduced by 'auto': %s" % origin)
         scm_data.url = origin
+
     if scm_data.revision == "auto":
         if not scm.is_pristine():
             output.warn("Repo status is not pristine: there might be modified files")
         scm_data.revision = scm.get_revision()
         output.success("Revision deduced by 'auto': %s" % scm_data.revision)
 
-    # Generate the scm_folder.txt file pointing to the src_path
-    src_path = scm.get_repo_root()
-    save(scm_src_file, src_path.replace("\\", "/"))
-    _replace_scm_data_in_conanfile(os.path.join(destination_folder, "conanfile.py"),
-                                   scm_data)
+    _replace_scm_data_in_conanfile(os.path.join(destination_folder, "conanfile.py"), scm_data)
 
     return scm_data, captured_revision
 
@@ -146,7 +148,6 @@ def _replace_scm_data_in_conanfile(conanfile_path, scm_data):
     content = content if not headers else ''.join(headers) + content
     save(conanfile_path, content)
 
-
 def _export_conanfile(conanfile_path, output, client_cache, conanfile, conan_ref, keep_source):
 
     exports_folder = client_cache.export(conan_ref)

conans/test/functional/old/scm_test.py

@@ -473,6 +473,70 @@ def scm_serialization_test(self):
         data2 = json.loads(the_json)
         self.assertEquals(data, data2)
 
+    def test_git_delegated_function(self):
+        conanfile = """
+import os
+from conans import ConanFile
+from conans.client.tools.scm import Git
+
+def get_revision():
+    here = os.path.dirname(__file__)
+    git = Git(here)
+    return git.get_commit()
+
+def get_url():
+    def nested_url():
+        here = os.path.dirname(__file__)
+        git = Git(here)
+        return git.get_remote_url()
+    return nested_url()
+
+class MyLib(ConanFile):
+    name = "issue"
+    version = "3831"
+    scm = {'type': 'git', 'url': get_url(), 'revision': get_revision()}
+
+"""
+        self.client.save({"conanfile.py": conanfile})
+        path, commit = create_local_git_repo(folder=self.client.current_folder)
+        self.client.runner('git remote add origin "%s"' % path.replace("\\", "/"), cwd=path)
+
+        self.client.run("export . user/channel")
+        reference = ConanFileReference.loads("issue/3831@user/channel")
+        exported_conanfile = self.client.client_cache.conanfile(reference)
+        content = load(exported_conanfile)
+        self.assertIn(commit, content)
+
+    def test_delegated_python_code(self):
+        conanfile = """
+from conans import ConanFile
+from recipe_code import get_commit
+
+class MyLib(ConanFile):
+    name = "issue"
+    version = "3831"
+    scm = {'type': 'git', 'url': 'url', 'revision': get_commit()}
+"""
+
+        code_file = """
+import os
+from conans.client.tools.scm import Git
+
+def get_commit():
+    here = os.path.dirname(__file__)
+    git = Git(here)
+    return git.get_commit()
+"""
+        self.client.save({"conanfile.py": conanfile, "recipe_code/__init__.py": code_file})
+        path, commit = create_local_git_repo(folder=self.client.current_folder)
+        self.client.runner('git remote add origin "%s"' % path.replace("\\", "/"), cwd=path)
+
+        self.client.run("export . user/channel")
+        reference = ConanFileReference.loads("issue/3831@user/channel")
+        exported_conanfile = self.client.client_cache.conanfile(reference)
+        content = load(exported_conanfile)
+        self.assertIn(commit, content)
+
 
 @attr('svn')
 class SVNSCMTest(SVNLocalRepoTestCase):