[nrf fromtree] scripts: check_compliance: Fix resource leak

The git diff subprocess was leaking, ie.,
it was still running with it's file streams open,
and python was printing warnings about this. Fix by calling
communicate() on the object which will do the cleanup.

Signed-off-by: Declan Snyder <[email protected]>
(cherry picked from commit 3b5bfd9)

Author: decsny

scripts/ci/check_compliance.py

@@ -291,37 +291,37 @@ def run(self):
             cmd = [checkpatch]
 
         cmd.extend(['--mailback', '--no-tree', '-'])
-        diff = subprocess.Popen(('git', 'diff', '--no-ext-diff', COMMIT_RANGE),
+        with subprocess.Popen(('git', 'diff', '--no-ext-diff', COMMIT_RANGE),
                                 stdout=subprocess.PIPE,
-                                cwd=GIT_TOP)
-        try:
-            subprocess.run(cmd,
-                           check=True,
-                           stdin=diff.stdout,
-                           stdout=subprocess.PIPE,
-                           stderr=subprocess.STDOUT,
-                           shell=False, cwd=GIT_TOP)
+                                cwd=GIT_TOP) as diff:
+            try:
+                subprocess.run(cmd,
+                               check=True,
+                               stdin=diff.stdout,
+                               stdout=subprocess.PIPE,
+                               stderr=subprocess.STDOUT,
+                               shell=False, cwd=GIT_TOP)
 
-        except subprocess.CalledProcessError as ex:
-            output = ex.output.decode("utf-8")
-            regex = r'^\s*\S+:(\d+):\s*(ERROR|WARNING):(.+?):(.+)(?:\n|\r\n?)+' \
-                    r'^\s*#(\d+):\s*FILE:\s*(.+):(\d+):'
+            except subprocess.CalledProcessError as ex:
+                output = ex.output.decode("utf-8")
+                regex = r'^\s*\S+:(\d+):\s*(ERROR|WARNING):(.+?):(.+)(?:\n|\r\n?)+' \
+                        r'^\s*#(\d+):\s*FILE:\s*(.+):(\d+):'
 
-            matches = re.findall(regex, output, re.MULTILINE)
+                matches = re.findall(regex, output, re.MULTILINE)
 
-            # add a guard here for excessive number of errors, do not try and
-            # process each one of them and instead push this as one failure.
-            if len(matches) > 500:
-                self.failure(output)
-                return
+                # add a guard here for excessive number of errors, do not try and
+                # process each one of them and instead push this as one failure.
+                if len(matches) > 500:
+                    self.failure(output)
+                    return
 
-            for m in matches:
-                self.fmtd_failure(m[1].lower(), m[2], m[5], m[6], col=None,
-                        desc=m[3])
+                for m in matches:
+                    self.fmtd_failure(m[1].lower(), m[2], m[5], m[6], col=None,
+                            desc=m[3])
 
-            # If the regex has not matched add the whole output as a failure
-            if len(matches) == 0:
-                self.failure(output)
+                # If the regex has not matched add the whole output as a failure
+                if len(matches) == 0:
+                    self.failure(output)
 
 
 class BoardYmlCheck(ComplianceTest):