SERVER-73047 add mongo tidy check unittests

11 files changed, 409 insertions, 50 deletions

diff --git a/buildscripts/linter/simplecpplint.py b/buildscripts/linter/simplecpplint.py
index e3c3685a6c1..f668c9e638f 100644
--- a/buildscripts/linter/simplecpplint.py
+++ b/buildscripts/linter/simplecpplint.py
@@ -404,6 +404,13 @@ class Linter:
             if "enterprise" in self.file_name:
                 return
 
+            norm_file_name = self.file_name.replace('\\', '/')
+
+            # Custom clang-tidy check tests purposefully produce errors for
+            # tests to find, they should be ignored.
+            if "mongo_tidy_checks/tests/" in norm_file_name:
+                return
+
             # The following files are in the src/mongo/ directory but technically belong
             # in src/third_party/ because their copyright does not belong to MongoDB.
             files_to_ignore = set([
@@ -419,7 +426,6 @@ class Linter:
                 'src/mongo/util/scopeguard.h',
             ])
 
-            norm_file_name = self.file_name.replace('\\', '/')
             for file_to_ignore in files_to_ignore:
                 if file_to_ignore in norm_file_name:
                     return
diff --git a/etc/evergreen_yml_components/definitions.yml b/etc/evergreen_yml_components/definitions.yml
index 01f382c3583..b80a4d69b0e 100644
--- a/etc/evergreen_yml_components/definitions.yml
+++ b/etc/evergreen_yml_components/definitions.yml
@@ -2764,7 +2764,7 @@ tasks:
     vars:
       task_compile_flags: >-
         --build-profile=compiledb
-      targets: compiledb
+      targets: compiledb +mongo-tidy-tests
       compiling_for_test: true
       compile_flags: >-
         --link-model=dynamic
diff --git a/site_scons/site_tools/compilation_db.py b/site_scons/site_tools/compilation_db.py
index 7e26b91d258..8bcf2398ce4 100644
--- a/site_scons/site_tools/compilation_db.py
+++ b/site_scons/site_tools/compilation_db.py
@@ -36,7 +36,7 @@ import itertools
 # compilation database can access the complete list, and also so that the writer has easy
 # access to write all of the files. But it seems clunky. How can the emitter and the scanner
 # communicate more gracefully?
-__COMPILATION_DB_ENTRIES = []
+__COMPILATION_DB_ENTRIES = {}
 
 # Cribbed from Tool/cc.py and Tool/c++.py. It would be better if
 # we could obtain this from SCons.
@@ -100,7 +100,12 @@ def makeEmitCompilationDbEntry(comstr):
         env.AlwaysBuild(entry)
         env.NoCache(entry)
 
-        __COMPILATION_DB_ENTRIES.append(dbtarget)
+        compiledb_target = env.get('COMPILEDB_TARGET')
+
+        if compiledb_target not in __COMPILATION_DB_ENTRIES:
+            __COMPILATION_DB_ENTRIES[compiledb_target] = []
+
+        __COMPILATION_DB_ENTRIES[compiledb_target].append(dbtarget)
 
         return target, source
 
@@ -137,7 +142,7 @@ def CompilationDbEntryAction(target, source, env, **kw):
 def WriteCompilationDb(target, source, env):
     entries = []
 
-    for s in __COMPILATION_DB_ENTRIES:
+    for s in __COMPILATION_DB_ENTRIES[target[0].abspath]:
         entries.append(s.read())
 
     with open(str(target[0]), "w") as target_file:
@@ -151,7 +156,10 @@ def WriteCompilationDb(target, source, env):
 
 
 def ScanCompilationDb(node, env, path):
-    return __COMPILATION_DB_ENTRIES
+    all_entries = []
+    for compiledb_target in __COMPILATION_DB_ENTRIES:
+        all_entries.extend(__COMPILATION_DB_ENTRIES[compiledb_target])
+    return all_entries
 
 
 def generate(env, **kwargs):
@@ -203,7 +211,9 @@ def generate(env, **kwargs):
     )
 
     def CompilationDatabase(env, target):
+
         result = env.__COMPILATIONDB_Database(target=target, source=[])
+        env['COMPILEDB_TARGET'] = result[0].abspath
 
         env.AlwaysBuild(result)
         env.NoCache(result)
diff --git a/src/mongo/tools/mongo_tidy_checks/MongoTestCheck.cpp b/src/mongo/tools/mongo_tidy_checks/MongoTestCheck.cpp
index eaccb77af78..72cbbc89872 100644
--- a/src/mongo/tools/mongo_tidy_checks/MongoTestCheck.cpp
+++ b/src/mongo/tools/mongo_tidy_checks/MongoTestCheck.cpp
@@ -26,11 +26,10 @@
  *    exception statement from all source files in the program, then also delete
  *    it in the license file.
  */
+#include "MongoTestCheck.h"
 
 #include "clang-tidy/ClangTidy.h"
 #include "clang-tidy/ClangTidyCheck.h"
-#include "clang-tidy/ClangTidyModule.h"
-#include "clang-tidy/ClangTidyModuleRegistry.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 
@@ -42,44 +41,21 @@ using namespace clang::ast_matchers;
 // This is a dummy reference check to give example for writing new checks.
 // This check should be removed (the file here and any references to it) once we have
 // some real checks.
-namespace {
-class MongoDummyCheck : public ClangTidyCheck {
+namespace mongo {
+namespace tidy {
 
-public:
-    MongoDummyCheck(StringRef Name, ClangTidyContext* Context) : ClangTidyCheck(Name, Context) {}
+MongoTestCheck::MongoTestCheck(StringRef Name, ClangTidyContext* Context)
+    : ClangTidyCheck(Name, Context) {}
 
-    void registerMatchers(ast_matchers::MatchFinder* Finder) override {
-        Finder->addMatcher(translationUnitDecl().bind("tu"), this);
-    }
+void MongoTestCheck::registerMatchers(ast_matchers::MatchFinder* Finder) {
+    Finder->addMatcher(translationUnitDecl().bind("tu"), this);
+}
 
-    void check(const ast_matchers::MatchFinder::MatchResult& Result) override {
-        auto S = Result.Nodes.getNodeAs<TranslationUnitDecl>("tu");
-        if (S)
-            diag("mytest success");
-    }
+void MongoTestCheck::check(const ast_matchers::MatchFinder::MatchResult& Result) {
+    auto S = Result.Nodes.getNodeAs<TranslationUnitDecl>("tu");
+    if (S)
+        diag("ran mongo-test-check!");
+}
 
-private:
-};
-
-class CTTestModule : public ClangTidyModule {
-public:
-    void addCheckFactories(ClangTidyCheckFactories& CheckFactories) override {
-        CheckFactories.registerCheck<MongoDummyCheck>("mongo-test-check");
-    }
-};
-}  // namespace
-
-namespace tidy1 {
-// Register the CTTestTidyModule using this statically initialized variable.
-static ClangTidyModuleRegistry::Add<::CTTestModule> X("mytest-module", "Adds my checks.");
-}  // namespace tidy1
-
-namespace tidy2 {
-// intentionally collide with an existing test group name, merging with it
-static ClangTidyModuleRegistry::Add<::CTTestModule> X("misc-module",
-                                                      "Adds miscellaneous lint checks.");
-}  // namespace tidy2
-
-// This anchor is used to force the linker to link in the generated object file
-// and thus register the CTTestModule.
-volatile int CTTestModuleAnchorSource = 0;
+}  // namespace tidy
+}  // namespace mongo
diff --git a/src/mongo/tools/mongo_tidy_checks/MongoTestCheck.h b/src/mongo/tools/mongo_tidy_checks/MongoTestCheck.h
new file mode 100644
index 00000000000..af1dbca4684
--- /dev/null
+++ b/src/mongo/tools/mongo_tidy_checks/MongoTestCheck.h
@@ -0,0 +1,56 @@
+/**
+ *    Copyright (C) 2023-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+#pragma once
+
+#include "clang-tidy/ClangTidy.h"
+#include "clang-tidy/ClangTidyCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang;
+using namespace clang::tidy;
+using namespace clang::ast_matchers;
+
+namespace mongo {
+namespace tidy {
+
+class MongoTestCheck : public ClangTidyCheck {
+
+public:
+    MongoTestCheck(StringRef Name, ClangTidyContext* Context);
+
+    void registerMatchers(ast_matchers::MatchFinder* Finder) override;
+
+    void check(const ast_matchers::MatchFinder::MatchResult& Result) override;
+
+private:
+};
+
+}  // namespace tidy
+}  // namespace mongo
diff --git a/src/mongo/tools/mongo_tidy_checks/MongoTidyModule.cpp b/src/mongo/tools/mongo_tidy_checks/MongoTidyModule.cpp
new file mode 100644
index 00000000000..533221d30b9
--- /dev/null
+++ b/src/mongo/tools/mongo_tidy_checks/MongoTidyModule.cpp
@@ -0,0 +1,57 @@
+/**
+ *    Copyright (C) 2023-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "MongoTestCheck.h"
+
+#include "clang-tidy/ClangTidy.h"
+#include "clang-tidy/ClangTidyCheck.h"
+#include "clang-tidy/ClangTidyModule.h"
+#include "clang-tidy/ClangTidyModuleRegistry.h"
+
+namespace mongo {
+namespace tidy {
+
+class MongoTidyModule : public ClangTidyModule {
+public:
+    void addCheckFactories(ClangTidyCheckFactories& CheckFactories) override {
+        CheckFactories.registerCheck<MongoTestCheck>("mongo-test-check");
+    }
+};
+
+// Register the MongoTidyModule using this statically initialized variable.
+static ClangTidyModuleRegistry::Add<MongoTidyModule> X("mongo-tidy-module",
+                                                       "MongoDB custom checks.");
+
+}  // namespace tidy
+
+// This anchor is used to force the linker to link in the generated object file
+// and thus register the MongoTidyModule.
+volatile int MongoTidyModuleAnchorSource = 0;
+
+}  // namespace mongo
diff --git a/src/mongo/tools/mongo_tidy_checks/SConscript b/src/mongo/tools/mongo_tidy_checks/SConscript
index d89da3e5926..9b0d75cbb96 100644
--- a/src/mongo/tools/mongo_tidy_checks/SConscript
+++ b/src/mongo/tools/mongo_tidy_checks/SConscript
@@ -4,13 +4,12 @@ from buildscripts.toolchains import DEFAULT_DATA_FILE, ToolchainConfig, Toolchai
 
 toolchain_clang_tidy_dev_found = False
 toolchain_found = False
-
+base_toolchain_bin = None
 try:
     toolchain_config = ToolchainConfig(DEFAULT_DATA_FILE, ToolchainPlatform('default'))
     toolchain_found = toolchain_config.base_path.exists()
-
-    base_revision_path = (toolchain_config.base_path / toolchain_config.aliases['stable'] / 'bin' /
-                          'clang-tidy').resolve().parent.parent
+    base_toolchain_bin = (toolchain_config.base_path / toolchain_config.aliases['stable'] / 'bin')
+    base_revision_path = (base_toolchain_bin / 'clang-tidy').resolve().parent.parent
 
     tidy_include = base_revision_path / 'include'
     tidy_lib = base_revision_path / 'lib'
@@ -123,6 +122,7 @@ mongo_custom_check = env.SharedLibrary(
     target="mongo_tidy_checks",
     source=[
         "MongoTestCheck.cpp",
+        "MongoTidyModule.cpp",
     ],
     LIBDEPS_NO_INHERIT=[
         '$BUILD_DIR/third_party/shim_allocator',
@@ -130,9 +130,16 @@ mongo_custom_check = env.SharedLibrary(
     AIB_COMPONENT='mongo-tidy-checks',
 )
 
-pretty_printer_test_installed = env.AutoInstall(
+env.AutoInstall(
     target='$PREFIX_LIBDIR',
     source=mongo_custom_check,
     AIB_ROLE='runtime',
     AIB_COMPONENT='mongo-tidy-checks',
 )
+mongo_tidy_module = env.GetAutoInstalledFiles(mongo_custom_check[0])[0]
+
+# because compiledb is required for use with clang-tidy and potentially clang-tidy is
+# loading the module, we add the module to the compiledb alias.
+env.Alias("compiledb", mongo_tidy_module)
+
+env.SConscript('tests/SConscript', exports=['env', 'mongo_tidy_module', 'base_toolchain_bin'])
diff --git a/src/mongo/tools/mongo_tidy_checks/tests/MongoTidyCheckTestMain.cpp b/src/mongo/tools/mongo_tidy_checks/tests/MongoTidyCheckTestMain.cpp
new file mode 100644
index 00000000000..5702e29e2cf
--- /dev/null
+++ b/src/mongo/tools/mongo_tidy_checks/tests/MongoTidyCheckTestMain.cpp
@@ -0,0 +1,32 @@
+/**
+ *    Copyright (C) 2023-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+int main(int argc, char* argv[]) {
+    return 0;
+}
diff --git a/src/mongo/tools/mongo_tidy_checks/tests/MongoTidyCheck_unittest.py b/src/mongo/tools/mongo_tidy_checks/tests/MongoTidyCheck_unittest.py
new file mode 100644
index 00000000000..99ce4906d31
--- /dev/null
+++ b/src/mongo/tools/mongo_tidy_checks/tests/MongoTidyCheck_unittest.py
@@ -0,0 +1,122 @@
+import unittest
+import subprocess
+import sys
+import tempfile
+import os
+import textwrap
+import argparse
+
+
+class MongoTidyTests(unittest.TestCase):
+    TIDY_BIN = None
+    TIDY_MODULE = None
+    COMPILE_COMMANDS_FILES = []
+
+    def write_config(self, config_str: str):
+        self.config_file = tempfile.NamedTemporaryFile(mode='w', delete=False)
+        self.config_file.write(config_str)
+        self.config_file.close()
+        self.cmd += [f'--clang-tidy-cfg={self.config_file.name}']
+        return self.config_file.name
+
+    def run_clang_tidy(self):
+        p = subprocess.run(self.cmd, capture_output=True, text=True)
+        passed = self.expected_output is not None and self.expected_output in p.stdout
+        with open(self.config_file.name) as f:
+            msg = '\n'.join([
+                '>' * 80,
+                f"Mongo Tidy Unittest {self._testMethodName}: {'PASSED' if passed else 'FAILED'}",
+                "",
+                "Command:",
+                ' '.join(self.cmd),
+                "",
+                "With config:",
+                f.read(),
+                "",
+                f"Exit code was: {p.returncode}",
+                "",
+                f"Output expected in stdout: {self.expected_output}",
+                "",
+                "stdout was:",
+                p.stdout,
+                "",
+                "stderr was:",
+                p.stderr,
+                "",
+                '<' * 80,
+            ])
+
+            if passed:
+                sys.stderr.write(msg)
+            else:
+                print(msg)
+                self.fail()
+                
+            with open(f'{os.path.splitext(self.compile_db)[0]}.results', 'w') as results:
+                results.write(msg)
+
+    def setUp(self):
+        self.config_file = None
+        self.expected_output = None
+        for compiledb in self.COMPILE_COMMANDS_FILES:
+            if compiledb.endswith("/" + self._testMethodName + ".json"):
+                self.compile_db = compiledb
+        if self.compile_db:
+            self.cmd = [
+                sys.executable,
+                'buildscripts/clang_tidy.py',
+                f'--check-module={self.TIDY_MODULE}',
+                f'--output-dir={os.path.join(os.path.dirname(compiledb), self._testMethodName + "_out")}',
+                f'--compile-commands={self.compile_db}',
+            ]
+        else:
+            raise(f"ERROR: did not findh matching compiledb for {self._testMethodName}")
+
+    def tearDown(self):
+        if self.config_file:
+            self.config_file.close()
+            os.unlink(self.config_file.name)
+
+    def test_MongoTestCheck(self):
+
+        self.write_config(
+            textwrap.dedent("""\
+                Checks: '-*,mongo-test-check'
+                WarningsAsErrors: '*'
+                """))
+        
+        self.expected_output = "ran mongo-test-check!"
+
+        self.run_clang_tidy()
+
+
+if __name__ == '__main__':
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--clang-tidy-path', default='/opt/mongodbtoolchain/v4/bin/clang-tidy',
+                        help="Path to clang-tidy binary.")
+    parser.add_argument('--mongo-tidy-module', default='build/install/lib/libmongo_tidy_checks.so',
+                        help="Path to mongo tidy check library.")
+    parser.add_argument(
+        '--test-compiledbs', action='append', default=[],
+        help="Used multiple times. Each use adds a test compilation database to use. " +
+        "The compilation database name must match the unittest method name.")
+    parser.add_argument('unittest_args', nargs='*')
+
+    args = parser.parse_args()
+
+    MongoTidyTests.TIDY_BIN = args.clang_tidy_path
+    MongoTidyTests.TIDY_MODULE = args.mongo_tidy_module
+    MongoTidyTests.COMPILE_COMMANDS_FILES = args.test_compiledbs
+
+    # We need to validate the toolchain can support the load operation for our module.
+    cmd = [MongoTidyTests.TIDY_BIN, f'-load', MongoTidyTests.TIDY_MODULE, '--list-checks']
+    p = subprocess.run(cmd, capture_output=True)
+    if p.returncode != 0:
+        print(f"Could not validate toolchain was able to load module {cmd}.")
+        sys.exit(1)
+
+    # Workaround to allow use to use argparse on top of unittest module.
+    sys.argv[1:] = args.unittest_args
+
+    unittest.main()
diff --git a/src/mongo/tools/mongo_tidy_checks/tests/SConscript b/src/mongo/tools/mongo_tidy_checks/tests/SConscript
new file mode 100644
index 00000000000..57b1cb01067
--- /dev/null
+++ b/src/mongo/tools/mongo_tidy_checks/tests/SConscript
@@ -0,0 +1,61 @@
+Import('env')
+Import('mongo_tidy_module')
+Import('base_toolchain_bin')
+
+import sys
+import os
+import SCons
+
+# multiple compilation databases is not supported by ninja
+if env.GetOption('ninja') == 'disabled':
+
+    # This list represents the test source files, which should contain a single issue which will be flagged
+    # by a clang tidy check. The issue should be isolated in as minimal way as possible.
+    tests = [
+        'test_MongoTestCheck.cpp',
+    ]
+
+    # So that we can do fast runs, we will generate a separate compilation database file for each
+    # unittest. To keep things simple we will name the compilation database file after the test.
+    # We need to create separate environments here because compilation database acts on the current
+    # environment.
+    test_objs = []
+    compilation_dbs = []
+    for test in tests:
+        test_env = env.Clone()
+        compilation_dbs += test_env.CompilationDatabase(
+            os.path.splitext(os.path.basename(test))[0] + ".json")
+        test_objs += test_env.Object(test)
+
+    # Building a program binary may not be necessary but it does validate the code and tie it together.
+    test_prog = env.Program(
+        target='MongoTidyCheck_test',
+        source=['MongoTidyCheckTestMain.cpp'] + test_objs,
+        LIBDEPS_NO_INHERIT=[
+            '$BUILD_DIR/third_party/shim_allocator',
+        ],
+    )
+
+    # Here we setup the test execution. The test will pythons built in unittest framework
+    # to execute clang tidy for each test source file from the list above.
+    test = env.Command(
+        target='run_MongoTidyCheck_test',
+        source=[
+            'MongoTidyCheck_unittest.py',
+            str(base_toolchain_bin / 'clang-tidy'), mongo_tidy_module.abspath
+        ] + compilation_dbs,
+        action=SCons.Action.Action(
+            ' '.join([
+                sys.executable,
+                '${SOURCES[0]}',
+                '--clang-tidy-path=${SOURCES[1]}',
+                '--mongo-tidy-module=${SOURCES[2]}',
+                '${["--test-compiledbs=%s" % src for src in SOURCES[3:]]}',
+                f"{'' if env.Verbose() else '2> /dev/null'}",
+            ]),
+            "" if env.Verbose() else "Runnning mongo tidy checks unittests.",
+        ),
+    )
+
+    env.Alias('+mongo-tidy-tests', test)
+    env.Depends(test, test_prog)
diff --git a/src/mongo/tools/mongo_tidy_checks/tests/test_MongoTestCheck.cpp b/src/mongo/tools/mongo_tidy_checks/tests/test_MongoTestCheck.cpp
new file mode 100644
index 00000000000..c1e2479f571
--- /dev/null
+++ b/src/mongo/tools/mongo_tidy_checks/tests/test_MongoTestCheck.cpp
@@ -0,0 +1,32 @@
+/**
+ *    Copyright (C) 2023-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the Server Side Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+void test_func(int test) {
+    test = 42;
+}