LINT: add clang-tidy step (#6295)

* Implement new travis clang-tidy build step

* This step enable some rules and enforce one rule as error
* This permits to have some C++ quality rules based on clang & clang contributor guidelines

* Fix clang-tidy reported problems on push_back -> emplace_back

8 files changed, 319 insertions, 8 deletions

diff --git a/.clang-tidy b/.clang-tidy
new file mode 100644
index 000000000..80c1949f9
--- /dev/null
+++ b/.clang-tidy
@@ -0,0 +1,4 @@
+Checks: '-*,modernize-use-emplace,modernize-use-default-member-init,modernize-use-equals-delete,modernize-use-equals-default,modernize-return-braced-init-list,modernize-loop-convert,modernize-avoid-bind,misc-throw-by-value-catch-by-reference,misc-string-compare,misc-inefficient-algorithm,misc-inaccurate-erase,misc-incorrect-roundings,misc-unconventional-assign-operator,bugprone-suspicious-memset-usage,performance-*'
+CheckOptions:
+  - key: modernize-use-default-member-init.UseAssignment
+    value: True
diff --git a/.travis.yml b/.travis.yml
index 0fb29fc7d..c506d21e7 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -96,6 +96,15 @@ matrix:
           packages: ['clang-format-5.0']
           sources: &sources
             - llvm-toolchain-trusty-5.0
+    - env: CLANG_TIDY=1
+      compiler: clang
+      os: linux
+      script: ./util/travis/clangtidy.sh
+      addons:
+        apt:
+          packages: ['clang-tidy-5.0']
+          sources: &sources
+            - llvm-toolchain-trusty-5.0
 
 
 
diff --git a/src/gui/guiEditBoxWithScrollbar.cpp b/src/gui/guiEditBoxWithScrollbar.cpp
index cf278a58e..4723437bd 100644
--- a/src/gui/guiEditBoxWithScrollbar.cpp
+++ b/src/gui/guiEditBoxWithScrollbar.cpp
@@ -743,7 +743,7 @@ void GUIEditBoxWithScrollBar::draw()
 				if (m_passwordbox) {
 					if (m_broken_text.size() != 1) {
 						m_broken_text.clear();
-						m_broken_text.push_back(core::stringw());
+						m_broken_text.emplace_back();
 					}
 					if (m_broken_text[0].size() != Text.size()){
 						m_broken_text[0] = Text;
diff --git a/src/script/cpp_api/s_env.cpp b/src/script/cpp_api/s_env.cpp
index 170640ce0..c9b652096 100644
--- a/src/script/cpp_api/s_env.cpp
+++ b/src/script/cpp_api/s_env.cpp
@@ -116,12 +116,12 @@ void ScriptApiEnv::initializeEnvironment(ServerEnvironment *env)
 			while (lua_next(L, table)) {
 				// key at index -2 and value at index -1
 				luaL_checktype(L, -1, LUA_TSTRING);
-				trigger_contents.push_back(lua_tostring(L, -1));
+				trigger_contents.emplace_back(lua_tostring(L, -1));
 				// removes value, keeps key for next iteration
 				lua_pop(L, 1);
 			}
 		} else if (lua_isstring(L, -1)) {
-			trigger_contents.push_back(lua_tostring(L, -1));
+			trigger_contents.emplace_back(lua_tostring(L, -1));
 		}
 		lua_pop(L, 1);
 
@@ -133,12 +133,12 @@ void ScriptApiEnv::initializeEnvironment(ServerEnvironment *env)
 			while (lua_next(L, table)) {
 				// key at index -2 and value at index -1
 				luaL_checktype(L, -1, LUA_TSTRING);
-				required_neighbors.push_back(lua_tostring(L, -1));
+				required_neighbors.emplace_back(lua_tostring(L, -1));
 				// removes value, keeps key for next iteration
 				lua_pop(L, 1);
 			}
 		} else if (lua_isstring(L, -1)) {
-			required_neighbors.push_back(lua_tostring(L, -1));
+			required_neighbors.emplace_back(lua_tostring(L, -1));
 		}
 		lua_pop(L, 1);
 
diff --git a/util/travis/before_install.sh b/util/travis/before_install.sh
index afc16c332..19c40ef90 100755
--- a/util/travis/before_install.sh
+++ b/util/travis/before_install.sh
@@ -10,8 +10,8 @@ fi
 
 needs_compile || exit 0
 
-if [[ $PLATFORM == "Unix" ]]; then
-	if [[ $TRAVIS_OS_NAME == "linux" ]]; then
+if [[ $PLATFORM == "Unix" ]] || [[ $CLANG_TIDY == "1" ]]; then
+	if [[ $TRAVIS_OS_NAME == "linux" ]] || [[ $CLANG_TIDY == "1" ]]; then
 		install_linux_deps
 	else
 		install_macosx_deps
diff --git a/util/travis/clangtidy.sh b/util/travis/clangtidy.sh
new file mode 100755
index 000000000..2d44afe32
--- /dev/null
+++ b/util/travis/clangtidy.sh
@@ -0,0 +1,27 @@
+if hash clang-tidy-5.0 2>/dev/null; then
+	CLANG_TIDY=clang-tidy-5.0
+else
+	CLANG_TIDY=clang-tidy
+fi
+
+files_to_analyze="$(find src/ -name '*.cpp' -or -name '*.h')"
+
+mkdir -p cmakebuild && cd cmakebuild
+cmake -DCMAKE_BUILD_TYPE=Debug \
+	-DCMAKE_EXPORT_COMPILE_COMMANDS=ON \
+	-DRUN_IN_PLACE=TRUE \
+	-DENABLE_GETTEXT=TRUE \
+	-DENABLE_SOUND=FALSE \
+	-DBUILD_SERVER=TRUE ..
+make GenerateVersion
+cd ..
+
+echo "Performing clang-tidy checks..."
+./util/travis/run-clang-tidy.py -clang-tidy-binary=${CLANG_TIDY} -p cmakebuild \
+	-checks='-*,modernize-use-emplace,modernize-avoid-bind,performance-*' \
+	-warningsaserrors='-*,modernize-use-emplace' \
+	-no-command-on-stdout -quiet \
+	files 'src/.*'
+RET=$?
+echo "Clang tidy returned $RET"
+exit $RET
diff --git a/util/travis/run-clang-tidy.py b/util/travis/run-clang-tidy.py
new file mode 100755
index 000000000..779cf7cc6
--- /dev/null
+++ b/util/travis/run-clang-tidy.py
@@ -0,0 +1,271 @@
+#!/usr/bin/env python2
+#
+# ===- run-clang-tidy.py - Parallel clang-tidy runner ---------*- python -*--===#
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is distributed under the University of Illinois Open Source
+# License. See LICENSE.TXT for details.
+#
+# ===------------------------------------------------------------------------===#
+# FIXME: Integrate with clang-tidy-diff.py
+
+"""
+Parallel clang-tidy runner
+==========================
+
+Runs clang-tidy over all files in a compilation database. Requires clang-tidy
+and clang-apply-replacements in $PATH.
+
+Example invocations.
+- Run clang-tidy on all files in the current working directory with a default
+  set of checks and show warnings in the cpp files and all project headers.
+    run-clang-tidy.py $PWD
+
+- Fix all header guards.
+    run-clang-tidy.py -fix -checks=-*,llvm-header-guard
+
+- Fix all header guards included from clang-tidy and header guards
+  for clang-tidy headers.
+    run-clang-tidy.py -fix -checks=-*,llvm-header-guard extra/clang-tidy \
+                      -header-filter=extra/clang-tidy
+
+Compilation database setup:
+http://clang.llvm.org/docs/HowToSetupToolingForLLVM.html
+"""
+
+from __future__ import print_function
+import argparse
+import json
+import multiprocessing
+import os
+import Queue
+import re
+import shutil
+import subprocess
+import sys
+import tempfile
+import threading
+import traceback
+
+
+class TidyQueue(Queue.Queue):
+    def __init__(self, max_task):
+        Queue.Queue.__init__(self, max_task)
+        self.has_error = False
+
+
+def find_compilation_database(path):
+    """Adjusts the directory until a compilation database is found."""
+    result = './'
+    while not os.path.isfile(os.path.join(result, path)):
+        if os.path.realpath(result) == '/':
+            print('Error: could not find compilation database.')
+            sys.exit(1)
+        result += '../'
+    return os.path.realpath(result)
+
+
+def get_tidy_invocation(f, clang_tidy_binary, checks, warningsaserrors,
+                        tmpdir, build_path,
+                        header_filter, extra_arg, extra_arg_before, quiet):
+    """Gets a command line for clang-tidy."""
+    start = [clang_tidy_binary]
+    if header_filter is not None:
+        start.append('-header-filter=' + header_filter)
+    else:
+        # Show warnings in all in-project headers by default.
+        start.append('-header-filter=^' + build_path + '/.*')
+    if checks:
+        start.append('-checks=' + checks)
+    if warningsaserrors:
+        start.append('-warnings-as-errors=' + warningsaserrors)
+    if tmpdir is not None:
+        start.append('-export-fixes')
+        # Get a temporary file. We immediately close the handle so clang-tidy can
+        # overwrite it.
+        (handle, name) = tempfile.mkstemp(suffix='.yaml', dir=tmpdir)
+        os.close(handle)
+        start.append(name)
+    for arg in extra_arg:
+        start.append('-extra-arg=%s' % arg)
+    for arg in extra_arg_before:
+        start.append('-extra-arg-before=%s' % arg)
+    start.append('-p=' + build_path)
+    if quiet:
+        start.append('-quiet')
+    start.append(f)
+    return start
+
+
+def check_clang_apply_replacements_binary(args):
+    """Checks if invoking supplied clang-apply-replacements binary works."""
+    try:
+        subprocess.check_call([args.clang_apply_replacements_binary, '--version'])
+    except:
+        print('Unable to run clang-apply-replacements. Is clang-apply-replacements '
+              'binary correctly specified?', file=sys.stderr)
+        traceback.print_exc()
+        sys.exit(1)
+
+
+def apply_fixes(args, tmpdir):
+    """Calls clang-apply-fixes on a given directory. Deletes the dir when done."""
+    invocation = [args.clang_apply_replacements_binary]
+    if args.format:
+        invocation.append('-format')
+    if args.style:
+        invocation.append('-style=' + args.style)
+    invocation.append(tmpdir)
+    subprocess.call(invocation)
+
+
+def run_tidy(args, tmpdir, build_path, queue):
+    """Takes filenames out of queue and runs clang-tidy on them."""
+    while True:
+        name = queue.get()
+        invocation = get_tidy_invocation(name, args.clang_tidy_binary, args.checks,
+                                         args.warningsaserrors, tmpdir, build_path,
+                                         args.header_filter, args.extra_arg,
+                                         args.extra_arg_before, args.quiet)
+        if not args.no_command_on_stdout:
+            sys.stdout.write(' '.join(invocation) + '\n')
+        try:
+            subprocess.check_call(invocation)
+        except subprocess.CalledProcessError:
+            queue.has_error = True
+        queue.task_done()
+
+
+def main():
+    parser = argparse.ArgumentParser(description='Runs clang-tidy over all files '
+                                                 'in a compilation database. Requires '
+                                                 'clang-tidy and clang-apply-replacements in '
+                                                 '$PATH.')
+    parser.add_argument('-clang-tidy-binary', metavar='PATH',
+                        default='clang-tidy',
+                        help='path to clang-tidy binary')
+    parser.add_argument('-clang-apply-replacements-binary', metavar='PATH',
+                        default='clang-apply-replacements',
+                        help='path to clang-apply-replacements binary')
+    parser.add_argument('-checks', default=None,
+                        help='checks filter, when not specified, use clang-tidy '
+                             'default')
+    parser.add_argument('-warningsaserrors', default=None,
+                        help='warnings-as-errors filter, when not specified, '
+                             'use clang-tidy default')
+    parser.add_argument('-header-filter', default=None,
+                        help='regular expression matching the names of the '
+                             'headers to output diagnostics from. Diagnostics from '
+                             'the main file of each translation unit are always '
+                             'displayed.')
+    parser.add_argument('-j', type=int, default=0,
+                        help='number of tidy instances to be run in parallel.')
+    parser.add_argument('files', nargs='*', default=['.*'],
+                        help='files to be processed (regex on path)')
+    parser.add_argument('-fix', action='store_true', help='apply fix-its')
+    parser.add_argument('-format', action='store_true', help='Reformat code '
+                                                             'after applying fixes')
+    parser.add_argument('-style', default='file', help='The style of reformat '
+                                                       'code after applying fixes')
+    parser.add_argument('-p', dest='build_path',
+                        help='Path used to read a compile command database.')
+    parser.add_argument('-extra-arg', dest='extra_arg',
+                        action='append', default=[],
+                        help='Additional argument to append to the compiler '
+                             'command line.')
+    parser.add_argument('-extra-arg-before', dest='extra_arg_before',
+                        action='append', default=[],
+                        help='Additional argument to prepend to the compiler '
+                             'command line.')
+    parser.add_argument('-quiet', action='store_true',
+                        help='Run clang-tidy in quiet mode')
+    parser.add_argument('-no-command-on-stdout', action='store_true',
+                        help='Run clang-tidy without printing invocation on '
+                             'stdout')
+    args = parser.parse_args()
+
+    db_path = 'compile_commands.json'
+
+    if args.build_path is not None:
+        build_path = args.build_path
+    else:
+        # Find our database
+        build_path = find_compilation_database(db_path)
+
+    try:
+        invocation = [args.clang_tidy_binary, '-list-checks', '-p=' + build_path]
+        if args.checks:
+            invocation.append('-checks=' + args.checks)
+        if args.warningsaserrors:
+            invocation.append('-warnings-as-errors=' + args.warningsaserrors)
+        invocation.append('-')
+        print(subprocess.check_output(invocation))
+    except:
+        print("Unable to run clang-tidy.", file=sys.stderr)
+        sys.exit(1)
+
+    # Load the database and extract all files.
+    database = json.load(open(os.path.join(build_path, db_path)))
+    files = [entry['file'] for entry in database]
+
+    max_task = args.j
+    if max_task == 0:
+        max_task = multiprocessing.cpu_count()
+
+    tmpdir = None
+    if args.fix:
+        check_clang_apply_replacements_binary(args)
+        tmpdir = tempfile.mkdtemp()
+
+    # Build up a big regexy filter from all command line arguments.
+    file_name_re = re.compile('|'.join(args.files))
+
+    try:
+        # Spin up a bunch of tidy-launching threads.
+        queue = TidyQueue(max_task)
+        for _ in range(max_task):
+            t = threading.Thread(target=run_tidy,
+                                 args=(args, tmpdir, build_path, queue))
+            t.daemon = True
+            t.start()
+
+        # Fill the queue with files.
+        for name in files:
+            if file_name_re.search(name):
+                queue.put(name)
+
+        # Wait for all threads to be done.
+        queue.join()
+
+        # If one clang-tidy process found and error, exit with non-zero
+        # status
+        if queue.has_error:
+            sys.exit(2)
+
+    except KeyboardInterrupt:
+        # This is a sad hack. Unfortunately subprocess goes
+        # bonkers with ctrl-c and we start forking merrily.
+        print('\nCtrl-C detected, goodbye.')
+        if args.fix:
+            shutil.rmtree(tmpdir)
+        os.kill(0, 9)
+
+    if args.fix:
+        print('Applying fixes ...')
+        successfully_applied = False
+
+        try:
+            apply_fixes(args, tmpdir)
+            successfully_applied = True
+        except:
+            print('Error applying fixes.\n', file=sys.stderr)
+            traceback.print_exc()
+
+        shutil.rmtree(tmpdir)
+        if not successfully_applied:
+            sys.exit(1)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/util/travis/script.sh b/util/travis/script.sh
index c68638db4..32e8d2e36 100755
--- a/util/travis/script.sh
+++ b/util/travis/script.sh
@@ -5,7 +5,7 @@
 needs_compile || exit 0
 
 if [[ "$LINT" == "1" ]]; then
-	# Lint with exit CI
+	# Lint and exit CI
 	perform_lint
 	exit 0
 fi