diff --git a/src/im/keyboard/compose.cpp b/src/im/keyboard/compose.cpp
index d14b566c..88ab8029 100644
--- a/src/im/keyboard/compose.cpp
+++ b/src/im/keyboard/compose.cpp
@@ -6,7 +6,18 @@
  */
 
 #include "compose.h"
-#include <fcitx-utils/utf8.h>
+#include <cassert>
+#include <cstddef>
+#include <deque>
+#include <iterator>
+#include <string>
+#include <tuple>
+#include "fcitx-utils/key.h"
+#include "fcitx-utils/keysymgen.h"
+#include "fcitx-utils/log.h"
+#include "fcitx-utils/utf8.h"
+#include "fcitx/inputcontext.h"
+#include "fcitx/instance.h"
 
 namespace fcitx {
 
@@ -101,7 +112,7 @@ bool ComposeState::typeImpl(KeySym sym, std::string &result) {
     // check compose first.
     auto composeResult = instance_->processComposeString(inputContext_, sym);
     if (!composeResult) {
-        assert(composeBuffer_.size() > 0);
+        assert(!composeBuffer_.empty());
         if (instance_->isComposing(inputContext_)) {
             return true;
         }
diff --git a/src/im/keyboard/compose.h b/src/im/keyboard/compose.h
index 07c4b8ab..ea38ad6f 100644
--- a/src/im/keyboard/compose.h
+++ b/src/im/keyboard/compose.h
@@ -8,7 +8,10 @@
 #define _FCITX_IM_KEYBOARD_COMPOSE_H_
 
 #include <deque>
-#include <fcitx/instance.h>
+#include <string>
+#include <tuple>
+#include "fcitx-utils/key.h"
+#include "fcitx/instance.h"
 
 namespace fcitx {
 class ComposeState {
diff --git a/src/im/keyboard/isocodes.cpp b/src/im/keyboard/isocodes.cpp
index 06746599..6abaf6dc 100644
--- a/src/im/keyboard/isocodes.cpp
+++ b/src/im/keyboard/isocodes.cpp
@@ -7,8 +7,12 @@
 
 #include "isocodes.h"
 #include <cstring>
-#include <json-c/json.h>
+#include <string>
+#include <json-c/json_object.h>
+#include <json-c/json_types.h>
+#include <json-c/json_util.h>
 #include "fcitx-utils/metastring.h"
+#include "fcitx-utils/misc.h"
 
 namespace fcitx {
 
@@ -112,7 +116,8 @@ class IsoCodes3166Parser
         if (!alpha2 || json_object_get_type(alpha2) != json_type_string) {
             return;
         }
-        std::string alpha_2_code, name;
+        std::string alpha_2_code;
+        std::string name;
         name.assign(json_object_get_string(nameObj),
                     json_object_get_string_len(nameObj));
         alpha_2_code.assign(json_object_get_string(alpha2),
diff --git a/src/im/keyboard/isocodes.h b/src/im/keyboard/isocodes.h
index 71e0fee15..eb38972c 100644
--- a/src/im/keyboard/isocodes.h
+++ b/src/im/keyboard/isocodes.h
@@ -10,7 +10,7 @@
 #include <string>
 #include <unordered_map>
 #include <vector>
-#include "fcitx/misc_p.h"
+#include "fcitx-utils/misc_p.h"
 
 namespace fcitx {
 
diff --git a/src/im/keyboard/keyboard.cpp b/src/im/keyboard/keyboard.cpp
index eaa6c7f8..4007017d 100644
--- a/src/im/keyboard/keyboard.cpp
+++ b/src/im/keyboard/keyboard.cpp
@@ -6,20 +6,50 @@
  */
 
 #include "keyboard.h"
-#include <algorithm>
+#include <strings.h>
+#include <cstddef>
+#include <functional>
+#include <iterator>
+#include <memory>
+#include <optional>
+#include <set>
+#include <string>
+#include <string_view>
+#include <tuple>
+#include <utility>
+#include <vector>
+#include <fmt/core.h>
 #include <fmt/format.h>
 #include <xkbcommon/xkbcommon.h>
 #include "fcitx-config/iniparser.h"
+#include "fcitx-config/rawconfig.h"
+#include "fcitx-utils/capabilityflags.h"
+#include "fcitx-utils/event.h"
 #include "fcitx-utils/i18n.h"
+#include "fcitx-utils/key.h"
+#include "fcitx-utils/keysym.h"
+#include "fcitx-utils/keysymgen.h"
+#include "fcitx-utils/macros.h"
+#include "fcitx-utils/misc.h"
+#include "fcitx-utils/misc_p.h"
 #include "fcitx-utils/stringutils.h"
+#include "fcitx-utils/textformatflags.h"
 #include "fcitx-utils/utf8.h"
+#include "fcitx/candidatelist.h"
+#include "fcitx/event.h"
+#include "fcitx/inputcontext.h"
 #include "fcitx/inputcontextmanager.h"
 #include "fcitx/inputcontextproperty.h"
 #include "fcitx/inputmethodentry.h"
 #include "fcitx/inputpanel.h"
 #include "fcitx/instance.h"
+#include "fcitx/misc_p.h"
+#include "fcitx/text.h"
+#include "fcitx/userinterface.h"
 #include "chardata.h"
 #include "config.h"
+#include "emoji_public.h"
+#include "isocodes.h"
 #include "longpress.h"
 #include "notifications_public.h"
 #include "quickphrase_public.h"
@@ -30,9 +60,6 @@
 #include "xcb_public.h"
 #endif
 
-#include <fcitx/inputcontext.h>
-#include "emoji_public.h"
-
 const char imNamePrefix[] = "keyboard-";
 #define FCITX_KEYBOARD_MAX_BUFFER 20
 
@@ -131,7 +158,7 @@ class LongPressCandidateWord : public CandidateWord {
     const std::string &str() const { return text_; }
 
     void select(InputContext *inputContext) const override {
-        auto state = inputContext->propertyFor(engine_->factory());
+        auto *state = inputContext->propertyFor(engine_->factory());
         state->mode_ = CandidateMode::Hint;
         // Make sure the candidate is from not from long press mode.
         inputContext->inputPanel().setCandidateList(nullptr);
@@ -358,7 +385,7 @@ static inline bool isValidSym(const Key &key) {
 static KeyList FCITX_HYPHEN_APOS = Key::keyListFromString("minus apostrophe");
 
 bool KeyboardEngineState::updateBuffer(std::string_view chr) {
-    auto *entry = engine_->instance()->inputMethodEntry(inputContext_);
+    const auto *entry = engine_->instance()->inputMethodEntry(inputContext_);
     if (!entry) {
         return false;
     }
@@ -472,7 +499,7 @@ bool KeyboardEngine::supportHint(const std::string &language) {
     return hasSpell || hasEmoji;
 }
 
-void KeyboardEngineState::setPreedit() {
+void KeyboardEngineState::setPreedit() const {
     const bool useClientPreedit =
         inputContext_->capabilityFlags().test(CapabilityFlag::Preedit);
     auto preeditText = preeditString();
@@ -499,7 +526,7 @@ void KeyboardEngineState::setPreedit() {
 void KeyboardEngineState::updateCandidate(const InputMethodEntry &entry) {
     inputContext_->inputPanel().reset();
     std::vector<std::pair<std::string, std::string>> results;
-    if (auto spell = engine_->spell()) {
+    if (auto *spell = engine_->spell()) {
         results = spell->call<ISpell::hintForDisplay>(
             entry.languageCode(), SpellProvider::Default, buffer_.userInput(),
             engine_->config().pageSize.value());
@@ -540,7 +567,7 @@ void KeyboardEngine::resetState(InputContext *inputContext) {
     state->reset();
 }
 
-void KeyboardEngine::deactivate(const InputMethodEntry &,
+void KeyboardEngine::deactivate(const InputMethodEntry & /*entry*/,
                                 InputContextEvent &event) {
     auto *inputContext = event.inputContext();
     auto *state = inputContext->propertyFor(&factory_);
@@ -556,7 +583,8 @@ void KeyboardEngine::deactivate(const InputMethodEntry &,
     inputContext->updateUserInterface(UserInterfaceComponent::InputPanel);
 }
 
-void KeyboardEngine::reset(const InputMethodEntry &, InputContextEvent &event) {
+void KeyboardEngine::reset(const InputMethodEntry & /*entry*/,
+                           InputContextEvent &event) {
     auto *inputContext = event.inputContext();
     auto *state = inputContext->propertyFor(&factory_);
     state->reset();
@@ -565,7 +593,7 @@ void KeyboardEngine::reset(const InputMethodEntry &, InputContextEvent &event) {
     inputContext->updateUserInterface(UserInterfaceComponent::InputPanel);
 }
 
-void KeyboardEngine::invokeActionImpl(const InputMethodEntry &,
+void KeyboardEngine::invokeActionImpl(const InputMethodEntry & /*entry*/,
                                       InvokeActionEvent &event) {
     auto *inputContext = event.inputContext();
     auto *state = inputContext->propertyFor(&factory_);
@@ -685,7 +713,7 @@ bool KeyboardEngineState::handleLongPress(const KeyEvent &event) {
         event.rawKey().states().test(KeyState::Repeat) &&
         *engine_->config().enableLongPress &&
         !engine_->isBlockedForLongPress(inputContext->program())) {
-        if (auto results = findValue(engine_->longPressData(), keystr)) {
+        if (const auto *results = findValue(engine_->longPressData(), keystr)) {
             if (repeatStarted_) {
                 return true;
             }
@@ -752,7 +780,8 @@ bool KeyboardEngineState::handleSpellModeTrigger(const InputMethodEntry &entry,
     return false;
 }
 
-bool KeyboardEngineState::handleCandidateSelection(const KeyEvent &event) {
+bool KeyboardEngineState::handleCandidateSelection(
+    const KeyEvent &event) const {
     // check if we can select candidate.
     auto candList = inputContext_->inputPanel().candidateList();
     if (!candList) {
@@ -821,7 +850,8 @@ std::string KeyboardEngineState::currentSelection() const {
             }
         }
         return buffer_.userInput();
-    } else if (mode_ == CandidateMode::LongPress) {
+    }
+    if (mode_ == CandidateMode::LongPress) {
         if (candidateList && candidateList->cursorIndex() >= 0) {
             if (const auto *candidate =
                     dynamic_cast<const LongPressCandidateWord *>(
diff --git a/src/im/keyboard/keyboard.h b/src/im/keyboard/keyboard.h
index 231d84bc..9ede069c 100644
--- a/src/im/keyboard/keyboard.h
+++ b/src/im/keyboard/keyboard.h
@@ -7,18 +7,32 @@
 #ifndef _FCITX_IM_KEYBOARD_KEYBOARD_H_
 #define _FCITX_IM_KEYBOARD_KEYBOARD_H_
 
+#include <functional>
+#include <memory>
+#include <string>
+#include <string_view>
+#include <tuple>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
 #include "fcitx-config/configuration.h"
+#include "fcitx-config/enum.h"
 #include "fcitx-config/iniparser.h"
+#include "fcitx-config/option.h"
+#include "fcitx-config/rawconfig.h"
 #include "fcitx-utils/event.h"
+#include "fcitx-utils/handlertable.h"
 #include "fcitx-utils/i18n.h"
 #include "fcitx-utils/inputbuffer.h"
+#include "fcitx-utils/key.h"
 #include "fcitx/addonfactory.h"
+#include "fcitx/addoninstance.h"
 #include "fcitx/addonmanager.h"
+#include "fcitx/event.h"
 #include "fcitx/inputcontextproperty.h"
 #include "fcitx/inputmethodengine.h"
 #include "fcitx/instance.h"
 #include "compose.h"
-#include "isocodes.h"
 #include "keyboard_public.h"
 #include "longpress.h"
 #include "quickphrase_public.h"
@@ -112,7 +126,7 @@ struct KeyboardEngineState : public InputContextProperty {
     bool handleLongPress(const KeyEvent &event);
     bool handleSpellModeTrigger(const InputMethodEntry &entry,
                                 const KeyEvent &event);
-    bool handleCandidateSelection(const KeyEvent &event);
+    bool handleCandidateSelection(const KeyEvent &event) const;
     std::tuple<std::string, bool> handleCompose(const KeyEvent &event);
     bool handleBackspace(const InputMethodEntry &entry);
 
@@ -125,7 +139,7 @@ struct KeyboardEngineState : public InputContextProperty {
 
     void updateCandidate(const InputMethodEntry &entry);
     // Update preedit and send ui update.
-    void setPreedit();
+    void setPreedit() const;
 
     // Return true if chr is pushed to buffer.
     // Return false if chr will be skipped by buffer, usually this means caller
@@ -152,7 +166,8 @@ class KeyboardEngine final : public InputMethodEngineV3 {
 
     const Configuration *getSubConfig(const std::string &path) const override;
 
-    void setSubConfig(const std::string &, const fcitx::RawConfig &) override;
+    void setSubConfig(const std::string & /*unused*/,
+                      const fcitx::RawConfig & /*unused*/) override;
 
     void reset(const InputMethodEntry &entry,
                InputContextEvent &event) override;
diff --git a/src/im/keyboard/keyboard_public.h b/src/im/keyboard/keyboard_public.h
index c52ed1d2..f9793e7e 100644
--- a/src/im/keyboard/keyboard_public.h
+++ b/src/im/keyboard/keyboard_public.h
@@ -8,6 +8,8 @@
 #define _FCITX_IM_KEYBOARD_KEYBOARD_PUBLIC_H_
 
 #include <functional>
+#include <string>
+#include <vector>
 #include <fcitx/addoninstance.h>
 
 FCITX_ADDON_DECLARE_FUNCTION(
diff --git a/src/im/keyboard/longpress.cpp b/src/im/keyboard/longpress.cpp
index 697127f4..b88dc231 100644
--- a/src/im/keyboard/longpress.cpp
+++ b/src/im/keyboard/longpress.cpp
@@ -6,6 +6,11 @@
  *
  */
 #include "longpress.h"
+#include <list>
+#include <string>
+#include <unordered_map>
+#include <utility>
+#include <vector>
 
 namespace fcitx {
 
@@ -132,7 +137,7 @@ void setupDefaultLongPressConfig(LongPressConfig &config) {
             {"$", {"¢", "€", "£", "¥", "₹", "₽", "₺", "₩", "₱", "₿"}},
         };
     {
-        auto value = config.entries.mutableValue();
+        auto *value = config.entries.mutableValue();
         for (const auto &[key, candidates] : data) {
             LongPressEntryConfig entry;
             entry.key.setValue(key);
diff --git a/src/im/keyboard/longpress.h b/src/im/keyboard/longpress.h
index b00383e0..45c2cede 100644
--- a/src/im/keyboard/longpress.h
+++ b/src/im/keyboard/longpress.h
@@ -7,7 +7,11 @@
 #ifndef _FCITX5_IM_KEYBOARD_LONGPRESSDATA_H_
 #define _FCITX5_IM_KEYBOARD_LONGPRESSDATA_H_
 
+#include <string>
+#include <unordered_map>
+#include <vector>
 #include "fcitx-config/configuration.h"
+#include "fcitx-config/option.h"
 #include "fcitx-utils/i18n.h"
 
 namespace fcitx {
diff --git a/src/im/keyboard/xkbrules.cpp b/src/im/keyboard/xkbrules.cpp
index da607357..0eba1b57 100644
--- a/src/im/keyboard/xkbrules.cpp
+++ b/src/im/keyboard/xkbrules.cpp
@@ -6,8 +6,15 @@
  */
 
 #include "xkbrules.h"
+#include <algorithm>
+#include <cstddef>
 #include <cstring>
+#include <initializer_list>
+#include <iterator>
 #include <list>
+#include <string>
+#include <utility>
+#include <vector>
 #include "fcitx-utils/stringutils.h"
 #include "xmlparser.h"
 
@@ -34,8 +41,8 @@ struct XkbRulesParseState : public XMLParser {
                           array.begin());
     }
 
-    void startElement(const XML_Char *name, const XML_Char **attrs) override {
-        parseStack_.emplace_back(reinterpret_cast<const char *>(name));
+    void startElement(const char *name, const char **attrs) override {
+        parseStack_.emplace_back(std::string(name));
         textBuff_.clear();
 
         if (match({"layoutList", "layout", "configItem"})) {
@@ -46,8 +53,8 @@ struct XkbRulesParseState : public XMLParser {
             modelInfos_.emplace_back();
         } else if (match({"optionList", "group"})) {
             optionGroupInfos_.emplace_back();
-            int i = 0;
-            while (attrs && attrs[i * 2] != 0) {
+            ptrdiff_t i = 0;
+            while (attrs && attrs[i * 2] != nullptr) {
                 if (strcmp(reinterpret_cast<const char *>(attrs[i * 2]),
                            "allowMultipleSelection") == 0) {
                     optionGroupInfos_.back().exclusive =
@@ -60,8 +67,8 @@ struct XkbRulesParseState : public XMLParser {
         } else if (match({"optionList", "group", "option"})) {
             optionGroupInfos_.back().optionInfos.emplace_back();
         } else if (match({"xkbConfigRegistry"})) {
-            int i = 0;
-            while (attrs && attrs[i * 2] != 0) {
+            ptrdiff_t i = 0;
+            while (attrs && attrs[i * 2] != nullptr) {
                 if (strcmp(reinterpret_cast<const char *>(attrs[i * 2]),
                            "version") == 0 &&
                     strlen(reinterpret_cast<const char *>(attrs[i * 2 + 1])) !=
@@ -72,7 +79,7 @@ struct XkbRulesParseState : public XMLParser {
             }
         }
     }
-    void endElement(const XML_Char *) override {
+    void endElement(const char * /*name*/) override {
         auto text = stringutils::trimView(textBuff_);
         if (!text.empty()) {
             if (match({"layoutList", "layout", "configItem", "name"})) {
@@ -123,7 +130,7 @@ struct XkbRulesParseState : public XMLParser {
         textBuff_.clear();
         parseStack_.pop_back();
     }
-    void characterData(const XML_Char *ch, int len) override {
+    void characterData(const char *ch, int len) override {
         textBuff_.append(reinterpret_cast<const char *>(ch), len);
     }
 
diff --git a/src/im/keyboard/xmlparser.cpp b/src/im/keyboard/xmlparser.cpp
index 0ab436f4..adb8979d 100644
--- a/src/im/keyboard/xmlparser.cpp
+++ b/src/im/keyboard/xmlparser.cpp
@@ -6,10 +6,15 @@
  */
 
 #include "xmlparser.h"
+#include <cstdio>
+#include <string>
+#include <expat.h>
 #include "fcitx-utils/misc.h"
 #define XML_BUFFER_SIZE 4096
 
-bool fcitx::XMLParser::parse(const std::string &name) {
+namespace fcitx {
+
+bool XMLParser::parse(const std::string &name) {
     UniqueCPtr<XML_ParserStruct, XML_ParserFree> parser(
         XML_ParserCreate(nullptr));
     UniqueFilePtr input(std::fopen(name.c_str(), "r"));
@@ -25,12 +30,12 @@ bool fcitx::XMLParser::parse(const std::string &name) {
             auto *ctx = static_cast<XMLParser *>(data);
             ctx->startElement(element_name, atts);
         },
-        [](void *data, const XML_Char *name) {
+        [](void *data, const char *name) {
             auto *ctx = static_cast<XMLParser *>(data);
             ctx->endElement(name);
         });
     XML_SetCharacterDataHandler(parser.get(),
-                                [](void *data, const XML_Char *s, int len) {
+                                [](void *data, const char *s, int len) {
                                     auto *ctx = static_cast<XMLParser *>(data);
                                     ctx->characterData(s, len);
                                 });
@@ -49,3 +54,5 @@ bool fcitx::XMLParser::parse(const std::string &name) {
 
     return true;
 }
+
+} // namespace fcitx
diff --git a/src/im/keyboard/xmlparser.h b/src/im/keyboard/xmlparser.h
index b55c8a61..b5292e5d 100644
--- a/src/im/keyboard/xmlparser.h
+++ b/src/im/keyboard/xmlparser.h
@@ -18,9 +18,9 @@ class XMLParser {
     bool parse(const std::string &name);
 
 protected:
-    virtual void startElement(const XML_Char *, const XML_Char **) {}
-    virtual void endElement(const XML_Char *) {}
-    virtual void characterData(const XML_Char *, int) {}
+    virtual void startElement(const char *name, const char **attrs) = 0;
+    virtual void endElement(const char *) = 0;
+    virtual void characterData(const char *ch, int len) = 0;
 };
 } // namespace fcitx
 
diff --git a/src/lib/fcitx/addoninstance.h b/src/lib/fcitx/addoninstance.h
index 549948a3..30d311fc 100644
--- a/src/lib/fcitx/addoninstance.h
+++ b/src/lib/fcitx/addoninstance.h
@@ -9,7 +9,10 @@
 
 #include <functional>
 #include <memory>
+#include <string>
 #include <fcitx-config/configuration.h>
+#include <fcitx-config/rawconfig.h>
+#include <fcitx-utils/macros.h>
 #include <fcitx-utils/metastring.h>
 #include <fcitx/addoninfo.h>
 #include <fcitx/addoninstance_details.h> // IWYU pragma: export
@@ -162,18 +165,21 @@ class FCITXCORE_EXPORT AddonInstance {
     namespace fcitx {                                                          \
     template <>                                                                \
     struct AddonFunctionSignature<fcitxMakeMetaString(#NAME "::" #FUNCTION)> { \
-        typedef std::remove_reference_t<decltype(std::declval<SIGNATURE>())>   \
-            type;                                                              \
+        using type =                                                           \
+            std::remove_reference_t<decltype(std::declval<SIGNATURE>())>;      \
     };                                                                         \
     namespace I##NAME {                                                        \
         struct FUNCTION {                                                      \
-            typedef fcitxMakeMetaString(#NAME "::" #FUNCTION) Name;            \
+            using Name = fcitxMakeMetaString(#NAME "::" #FUNCTION);            \
             using Signature = AddonFunctionSignatureType<Name>;                \
         };                                                                     \
     }                                                                          \
     }
 
 #define FCITX_ADDON_EXPORT_FUNCTION(CLASS, FUNCTION)                           \
+    static_assert(std::is_same_v<::fcitx::I##CLASS::FUNCTION::Name,            \
+                                 fcitxMakeMetaString(#CLASS "::" #FUNCTION)>,  \
+                  "");                                                         \
     decltype(::fcitx::MakeAddonFunctionAdaptor(                                \
         &CLASS::FUNCTION)) FUNCTION##Adaptor{#CLASS "::" #FUNCTION, this,      \
                                              &CLASS::FUNCTION};                \