diff --git a/artifacts/compile_commands.json.tmpl b/artifacts/compile_commands.json.tmpl
index 7e178c0..925b65c 100644
--- a/artifacts/compile_commands.json.tmpl
+++ b/artifacts/compile_commands.json.tmpl
@@ -29,6 +29,11 @@
   "command": "{{CONDA_PREFIX}}/bin/clang++ -DGFLAGS_IS_A_DLL=0 -DGLOG_CUSTOM_PREFIX_SUPPORT -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I{{PROJECT_PATH}}/src -fvisibility-inlines-hidden -std=c++20 -fmessage-length=0 -march=nocona -mtune=haswell -ftree-vectorize -fPIC -fstack-protector-strong -fno-plt -O2 -ffunction-sections -pipe -isystem {{CONDA_PREFIX}}/include -O3 -DNDEBUG -fprofile-instr-generate -fcoverage-mapping -std=c++20 -o CMakeFiles/arx.dir/src/codegen/ast-to-object.cpp.o -c {{PROJECT_PATH}}/src/codegen/ast-to-object.cpp",
   "file": "{{PROJECT_PATH}}/src/codegen/ast-to-object.cpp"
 },
+{
+  "directory": "{{PROJECT_PATH}}/build",
+  "command": "{{CONDA_PREFIX}}/bin/clang++ -DGFLAGS_IS_A_DLL=0 -DGLOG_CUSTOM_PREFIX_SUPPORT -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I{{PROJECT_PATH}}/src -fvisibility-inlines-hidden -std=c++20 -fmessage-length=0 -march=nocona -mtune=haswell -ftree-vectorize -fPIC -fstack-protector-strong -fno-plt -O2 -ffunction-sections -pipe -isystem {{CONDA_PREFIX}}/include -O3 -DNDEBUG -fprofile-instr-generate -fcoverage-mapping -std=c++20 -o CMakeFiles/arx.dir/src/codegen/ast-to-stdout.cpp.o -c {{PROJECT_PATH}}/src/codegen/ast-to-stdout.cpp",
+  "file": "{{PROJECT_PATH}}/src/codegen/ast-to-stdout.cpp"
+},
 {
   "directory": "{{PROJECT_PATH}}/build",
   "command": "{{CONDA_PREFIX}}/bin/clang++ -DGFLAGS_IS_A_DLL=0 -DGLOG_CUSTOM_PREFIX_SUPPORT -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I{{PROJECT_PATH}}/src -fvisibility-inlines-hidden -std=c++20 -fmessage-length=0 -march=nocona -mtune=haswell -ftree-vectorize -fPIC -fstack-protector-strong -fno-plt -O2 -ffunction-sections -pipe -isystem {{CONDA_PREFIX}}/include -O3 -DNDEBUG -fprofile-instr-generate -fcoverage-mapping -std=c++20 -o CMakeFiles/arx.dir/src/utils.cpp.o -c {{PROJECT_PATH}}/src/utils.cpp",
@@ -94,6 +99,11 @@
   "command": "{{CONDA_PREFIX}}/bin/clang++ -DGFLAGS_IS_A_DLL=0 -DGLOG_CUSTOM_PREFIX_SUPPORT -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I{{PROJECT_PATH}}/src -I{{PROJECT_PATH}}/build/tests -fvisibility-inlines-hidden -std=c++20 -fmessage-length=0 -march=nocona -mtune=haswell -ftree-vectorize -fPIC -fstack-protector-strong -fno-plt -O2 -ffunction-sections -pipe -isystem {{CONDA_PREFIX}}/include -fsanitize=address -O1 -fno-omit-frame-pointer -fprofile-instr-generate -fcoverage-mapping -O3 -DNDEBUG -fprofile-instr-generate -fcoverage-mapping -std=c++20 -o tests/CMakeFiles/ArxTests.dir/__/src/codegen/ast-to-object.cpp.o -c {{PROJECT_PATH}}/src/codegen/ast-to-object.cpp",
   "file": "{{PROJECT_PATH}}/src/codegen/ast-to-object.cpp"
 },
+{
+  "directory": "{{PROJECT_PATH}}/build",
+  "command": "{{CONDA_PREFIX}}/bin/clang++ -DGFLAGS_IS_A_DLL=0 -DGLOG_CUSTOM_PREFIX_SUPPORT -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I{{PROJECT_PATH}}/src -I{{PROJECT_PATH}}/build/tests -fvisibility-inlines-hidden -std=c++20 -fmessage-length=0 -march=nocona -mtune=haswell -ftree-vectorize -fPIC -fstack-protector-strong -fno-plt -O2 -ffunction-sections -pipe -isystem {{CONDA_PREFIX}}/include -fsanitize=address -O1 -fno-omit-frame-pointer -fprofile-instr-generate -fcoverage-mapping -O3 -DNDEBUG -fprofile-instr-generate -fcoverage-mapping -std=c++20 -o tests/CMakeFiles/ArxTests.dir/__/src/codegen/ast-to-stdout.cpp.o -c {{PROJECT_PATH}}/src/codegen/ast-to-stdout.cpp",
+  "file": "{{PROJECT_PATH}}/src/codegen/ast-to-stdout.cpp"
+},
 {
   "directory": "{{PROJECT_PATH}}/build",
   "command": "{{CONDA_PREFIX}}/bin/clang++ -DGFLAGS_IS_A_DLL=0 -DGLOG_CUSTOM_PREFIX_SUPPORT -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I{{PROJECT_PATH}}/src -I{{PROJECT_PATH}}/build/tests -fvisibility-inlines-hidden -std=c++20 -fmessage-length=0 -march=nocona -mtune=haswell -ftree-vectorize -fPIC -fstack-protector-strong -fno-plt -O2 -ffunction-sections -pipe -isystem {{CONDA_PREFIX}}/include -fsanitize=address -O1 -fno-omit-frame-pointer -fprofile-instr-generate -fcoverage-mapping -O3 -DNDEBUG -fprofile-instr-generate -fcoverage-mapping -std=c++20 -o tests/CMakeFiles/ArxTests.dir/__/src/utils.cpp.o -c {{PROJECT_PATH}}/src/utils.cpp",
diff --git a/meson.build b/meson.build
index f24fb40..62554f6 100644
--- a/meson.build
+++ b/meson.build
@@ -2,11 +2,33 @@ project('arx', 'cpp', 'c',
   license : 'Apache-2.0',
   version : '1.5.0',  # semantic-release
   default_options : [
-    'warning_level=3',
+    'warning_level=everything',
     'cpp_std=c++20',
   ]
 )
 
+add_global_arguments(
+  '-Wpedantic',
+  '-Wno-c++98-compat-pedantic',
+  '-Wno-padded',
+  '-Wno-missing-prototypes',
+  '-Wshadow',
+  '-Wnon-virtual-dtor',
+  '-Wcast-align',
+  '-Wunused',
+  '-Woverloaded-virtual',
+  '-Wconversion',
+  '-Wsign-conversion',
+  '-Wdouble-promotion',
+  '-Wformat=2',
+  '-Wimplicit-fallthrough',
+  '-Wsuggest-override',
+  '-Wnull-dereference',
+  '-Wold-style-cast',
+  language : 'cpp'
+)
+
+
 PROJECT_PATH = meson.source_root()
 
 cxx = meson.get_compiler('cpp')
@@ -25,7 +47,7 @@ project_src_files = files(
   # note: note working yet
   # PROJECT_PATH + '/src/codegen/ast-to-llvm.cpp',
   PROJECT_PATH + '/src/codegen/ast-to-object.cpp',
-  PROJECT_PATH + '/src/codegen/ast-to-output.cpp',
+  PROJECT_PATH + '/src/codegen/ast-to-stdout.cpp',
   PROJECT_PATH + '/src/error.cpp',
   PROJECT_PATH + '/src/io.cpp',
   PROJECT_PATH + '/src/lexer.cpp',
diff --git a/src/codegen/ast-to-object.cpp b/src/codegen/ast-to-object.cpp
index ff3b6dd..e13a303 100644
--- a/src/codegen/ast-to-object.cpp
+++ b/src/codegen/ast-to-object.cpp
@@ -106,9 +106,8 @@ class ASTToObjectVisitor : public Visitor {
 };
 
 /**
- * @brief
- * @param Name
- * @return
+ * @brief Put the function defined by the given name to result_func.
+ * @param Name Function name
  *
  * First, see if the function has already been added to the current
  * module. If not, check whether we can codegen the declaration from some
@@ -127,10 +126,10 @@ auto ASTToObjectVisitor::getFunction(std::string Name) -> void {
 }
 
 /**
- * @brief
- * @param TheFunction
- * @param VarName
- * @return
+ * @brief Create the Entry Block Allocation.
+ * @param TheFunction The llvm function
+ * @param VarName The variable name
+ * @return An llvm allocation instance.
  *
  * CreateEntryBlockAlloca - Create an alloca instruction in the entry
  * block of the function.  This is used for mutable variables etc.
@@ -143,14 +142,17 @@ auto ASTToObjectVisitor::CreateEntryBlockAlloca(
     llvm::Type::getDoubleTy(*this->TheContext), nullptr, VarName);
 }
 
+/**
+ * @brief Set to nullptr result_val and result_func in order to avoid trash.
+ *
+ */
 auto ASTToObjectVisitor::clean() -> void {
   this->result_val = nullptr;
   this->result_func = nullptr;
 }
 
 /**
- * @brief
- * @return
+ * @brief Code generation for NumberExprAST.
  *
  */
 auto ASTToObjectVisitor::visit(NumberExprAST* expr) -> void {
@@ -159,8 +161,7 @@ auto ASTToObjectVisitor::visit(NumberExprAST* expr) -> void {
 }
 
 /**
- * @brief Stat a variable in the function.
- * @return The variable loaded into the llvm.
+ * @brief Code generation for VariableExprAST.
  *
  */
 auto ASTToObjectVisitor::visit(VariableExprAST* expr) -> void {
@@ -177,8 +178,7 @@ auto ASTToObjectVisitor::visit(VariableExprAST* expr) -> void {
 }
 
 /**
- * @brief
- * @return
+ * @brief Code generation for UnaryExprAST.
  *
  */
 auto ASTToObjectVisitor::visit(UnaryExprAST* expr) -> void {
@@ -201,8 +201,7 @@ auto ASTToObjectVisitor::visit(UnaryExprAST* expr) -> void {
 }
 
 /**
- * @brief
- * @return
+ * @brief Code generation for BinaryExprAST.
  *
  */
 auto ASTToObjectVisitor::visit(BinaryExprAST* expr) -> void {
@@ -278,8 +277,7 @@ auto ASTToObjectVisitor::visit(BinaryExprAST* expr) -> void {
 }
 
 /**
- * @brief Look up the name in the global module table.
- * @return
+ * @brief Code generation for CallExprAST.
  *
  */
 auto ASTToObjectVisitor::visit(CallExprAST* expr) -> void {
@@ -310,7 +308,7 @@ auto ASTToObjectVisitor::visit(CallExprAST* expr) -> void {
 }
 
 /**
- * @brief
+ * @brief Code generation for IfExprAST.
  */
 auto ASTToObjectVisitor::visit(IfExprAST* expr) -> void {
   expr->Cond.get()->accept(this);
@@ -384,6 +382,11 @@ auto ASTToObjectVisitor::visit(IfExprAST* expr) -> void {
   return;
 }
 
+/**
+ * @brief Code generation for ForExprAST.
+ *
+ * @param expr A `for` expression.
+ */
 auto ASTToObjectVisitor::visit(ForExprAST* expr) -> void {
   llvm::Function* TheFunction = this->Builder->GetInsertBlock()->getParent();
 
@@ -489,8 +492,7 @@ auto ASTToObjectVisitor::visit(ForExprAST* expr) -> void {
 }
 
 /**
- * @brief
- * @return Return the body computation.
+ * @brief Code generation for VarExprAST.
  *
  */
 auto ASTToObjectVisitor::visit(VarExprAST* expr) -> void {
@@ -550,8 +552,7 @@ auto ASTToObjectVisitor::visit(VarExprAST* expr) -> void {
 }
 
 /**
- * @brief
- * @return
+ * @brief Code generation for PrototypeExprAST.
  *
  */
 auto ASTToObjectVisitor::visit(PrototypeAST* expr) -> void {
@@ -574,8 +575,7 @@ auto ASTToObjectVisitor::visit(PrototypeAST* expr) -> void {
 }
 
 /**
- * @brief
- * @return
+ * @brief Code generation for FunctionExprAST.
  *
  * Transfer ownership of the prototype to the FunctionProtos map, but
  * keep a reference to it for use below.
@@ -634,7 +634,7 @@ auto ASTToObjectVisitor::visit(FunctionAST* expr) -> void {
 }
 
 /**
- * @brief Open a new module.
+ * @brief Initialize LLVM Module And PassManager.
  *
  */
 auto ASTToObjectVisitor::InitializeModuleAndPassManager() -> void {
@@ -647,7 +647,7 @@ auto ASTToObjectVisitor::InitializeModuleAndPassManager() -> void {
 }
 
 /**
- * @brief
+ * @brief The main loop that walks the AST.
  * top ::= definition | external | expression | ';'
  */
 auto ASTToObjectVisitor::MainLoop(TreeAST* ast) -> void {
@@ -671,7 +671,7 @@ auto ASTToObjectVisitor::MainLoop(TreeAST* ast) -> void {
  *
  */
 extern "C" DLLEXPORT auto putchard(double X) -> double {
-  fputc((char) X, stderr);
+  fputc(static_cast<char>(X), stderr);
   return 0;
 }
 
@@ -685,8 +685,9 @@ extern "C" DLLEXPORT auto printd(double X) -> double {
 }
 
 /**
- * @brief
+ * @brief Compile an AST to object file.
  *
+ * @param tree_ast The AST tree object.
  */
 auto compile(TreeAST* tree_ast) -> void {
   auto codegen = new ASTToObjectVisitor();
@@ -768,7 +769,7 @@ auto compile(TreeAST* tree_ast) -> void {
 }
 
 /**
- * @brief
+ * @brief Open the Arx shell.
  *
  */
 auto open_shell() -> void {
diff --git a/src/codegen/ast-to-output.cpp b/src/codegen/ast-to-stdout.cpp
similarity index 93%
rename from src/codegen/ast-to-output.cpp
rename to src/codegen/ast-to-stdout.cpp
index f5ee87d..cbcd499 100644
--- a/src/codegen/ast-to-output.cpp
+++ b/src/codegen/ast-to-stdout.cpp
@@ -1,4 +1,4 @@
-#include "ast-to-output.h"
+#include "ast-to-stdout.h"
 #include <iostream>
 #include "parser.h"
 
@@ -21,7 +21,8 @@ class ASTToOutputVisitor : public Visitor {
   virtual void visit(VarExprAST*) override;
   virtual void visit(PrototypeAST*) override;
   virtual void visit(FunctionAST*) override;
-  virtual void clean() override{};
+
+  virtual void clean() override {}
 
   auto indentation() -> std::string {
     std::string _indent(this->indent, ' ');
@@ -30,13 +31,13 @@ class ASTToOutputVisitor : public Visitor {
 
   auto set_annotation(std::string annotation) -> void {
     this->annotation = annotation;
-  };
+  }
 
   auto get_annotation() -> std::string {
     std::string _anno = this->annotation;
     this->annotation = "";
     return _anno;
-  };
+  }
 };
 
 void ASTToOutputVisitor::visit(NumberExprAST* expr) {
@@ -173,14 +174,24 @@ void ASTToOutputVisitor::visit(ForExprAST* expr) {
 
 void ASTToOutputVisitor::visit(VarExprAST* expr) {
   // TODO: implement it
-  std::cout << "(VarExprAST"
-            << ")" << std::endl;
+  std::cout << "(VarExprAST " << std::endl;
+  this->indent += INDENT_SIZE;
+
+  for (auto var_expr = expr->VarNames.begin();
+       var_expr != expr->VarNames.end();
+       ++var_expr) {
+    var_expr->second->accept(this);
+    std::cout << "," << std::endl;
+  }
+
+  this->indent -= INDENT_SIZE;
+
+  std::cout << ")" << std::endl;
 }
 
 void ASTToOutputVisitor::visit(PrototypeAST* expr) {
   // TODO: implement it
-  std::cout << "(PrototypeAST"
-            << ")" << std::endl;
+  std::cout << "(PrototypeAST " << expr->Name << ")" << std::endl;
 }
 
 void ASTToOutputVisitor::visit(FunctionAST* expr) {
diff --git a/src/codegen/ast-to-output.h b/src/codegen/ast-to-stdout.h
similarity index 100%
rename from src/codegen/ast-to-output.h
rename to src/codegen/ast-to-stdout.h
diff --git a/src/error.h b/src/error.h
index 203cfd4..1a03fa3 100644
--- a/src/error.h
+++ b/src/error.h
@@ -5,8 +5,7 @@
 
 namespace llvm {
   /**
-   * @brief
-   * "llvm/IR/Value.h"
+   * @brief "llvm/IR/Value.h"
    *
    */
   class Value;
diff --git a/src/io.cpp b/src/io.cpp
index 63212f8..50e12ae 100644
--- a/src/io.cpp
+++ b/src/io.cpp
@@ -12,8 +12,8 @@ std::string OUTPUT_FILE{""};
 bool INPUT_FROM_STDIN = false;
 
 /**
- * @brief
- * @return
+ * @brief Get a char from the buffer of from the default input.
+ * @return An integer represenation of a char from the buffer.
  *
  */
 auto get_char() -> int {
@@ -24,7 +24,7 @@ auto get_char() -> int {
 }
 
 /**
- * @brief
+ * @brief Copy the file content to the buffer.
  *
  */
 auto file_to_buffer(std::string filename) -> void {
@@ -41,7 +41,7 @@ auto file_to_buffer(std::string filename) -> void {
 }
 
 /**
- * @brief
+ * @brief Copy the given string to the buffer.
  *
  */
 auto string_to_buffer(std::string value) -> void {
@@ -51,7 +51,7 @@ auto string_to_buffer(std::string value) -> void {
 }
 
 /**
- * @brief
+ * @brief Load the content file or the standard input to the buffer.
  *
  */
 auto load_input_to_buffer() -> void {
diff --git a/src/jit.h b/src/jit.h
index 1fcdada..7496b5a 100644
--- a/src/jit.h
+++ b/src/jit.h
@@ -58,9 +58,9 @@ namespace llvm {
 
      public:
       /**
-       * @param ES
-       * @param JTMB
-       * @param DL
+       * @param ES ExecutionSession
+       * @param JTMB JITTargetMachineBuilder
+       * @param DL DataLayout
        */
       ArxJIT(
         std::unique_ptr<ExecutionSession> ES,
diff --git a/src/lexer.cpp b/src/lexer.cpp
index 883aafb..a545b3b 100644
--- a/src/lexer.cpp
+++ b/src/lexer.cpp
@@ -7,8 +7,6 @@
 #include "io.h"
 #include "lexer.h"
 
-std::stringstream buffer;
-
 SourceLocation Lexer::CurLoc;
 std::string Lexer::IdentifierStr =
   "<NOT DEFINED>";     // Filled in if tok_identifier
@@ -17,9 +15,9 @@ SourceLocation Lexer::LexLoc;
 int Lexer::CurTok = tok_not_initialized;
 
 /**
- * @brief
- * @param Tok
- * @return
+ * @brief Get the Token name.
+ * @param Tok The token
+ * @return Token name
  *
  */
 auto Lexer::getTokName(int Tok) -> std::string {
@@ -55,13 +53,13 @@ auto Lexer::getTokName(int Tok) -> std::string {
     case tok_const:
       return "const";
   }
-  return std::string(1, (char) Tok);
+  return std::string(1, static_cast<char>(Tok));
 }
 
 /**
- * @brief
- * @param c
- * @return
+ * @brief Check if given character is a valid first identifier character.
+ * @param c A single character for checking the token
+ * @return true if the token is valid, otherwise, false.
  *
  */
 static auto is_identifier_first_char(char c) -> bool {
@@ -69,9 +67,9 @@ static auto is_identifier_first_char(char c) -> bool {
 }
 
 /**
- * @brief
- * @param c
- * @return
+ * @brief Check if the given character is a valid identifier char.
+ * @param c Given character from a token.
+ * @return true if the is a valid character, otherwise, false.
  *
  */
 static auto is_identifier_char(char c) -> bool {
@@ -79,8 +77,8 @@ static auto is_identifier_char(char c) -> bool {
 }
 
 /**
- * @brief
- * @return
+ * @brief advance the token from the buffer.
+ * @return Token in integer form.
  *
  */
 auto Lexer::advance() -> int {
@@ -96,7 +94,7 @@ auto Lexer::advance() -> int {
 }
 
 /**
- * @brief
+ * @brief Get the next token.
  * @return Return the next token from standard input.
  *
  */
@@ -105,14 +103,15 @@ auto Lexer::gettok() -> int {
 
   // Skip any whitespace.
   while (isspace(LastChar)) {
-    LastChar = (char) Lexer::advance();
+    LastChar = static_cast<char>(Lexer::advance());
   }
 
   Lexer::CurLoc = Lexer::LexLoc;
 
   if (is_identifier_first_char(LastChar)) {
-    Lexer::IdentifierStr = (char) LastChar;
-    while (is_identifier_char((LastChar = (char) Lexer::advance()))) {
+    Lexer::IdentifierStr = static_cast<char>(LastChar);
+    while (
+      is_identifier_char((LastChar = static_cast<char>(Lexer::advance())))) {
       Lexer::IdentifierStr += LastChar;
     }
 
@@ -153,8 +152,8 @@ auto Lexer::gettok() -> int {
   if (isdigit(LastChar) || LastChar == '.') {
     std::string NumStr;
     do {
-      NumStr += (char) LastChar;
-      LastChar = (char) Lexer::advance();
+      NumStr += static_cast<char>(LastChar);
+      LastChar = static_cast<char>(Lexer::advance());
     } while (isdigit(LastChar) || LastChar == '.');
 
     Lexer::NumVal = strtod(NumStr.c_str(), nullptr);
@@ -164,7 +163,7 @@ auto Lexer::gettok() -> int {
   // Comment until end of line.
   if (LastChar == '#') {
     do {
-      LastChar = advance();
+      LastChar = static_cast<char>(Lexer::advance());
     } while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');
 
     if (LastChar != EOF) {
@@ -179,14 +178,13 @@ auto Lexer::gettok() -> int {
 
   // Otherwise, just return the character as its ascii value.
   int ThisChar = LastChar;
-  LastChar = Lexer::advance();
+  LastChar = static_cast<char>(Lexer::advance());
   return ThisChar;
 }
 
 /**
  * @brief Provide a simple token buffer.
  * @return
-
  * CurTok is the current token the parser is looking at.
  * getNextToken reads another token from the lexer and updates
  * CurTok with its results.
diff --git a/src/main.cpp b/src/main.cpp
index 7c9c755..43fbbf7 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -22,7 +22,7 @@
 
 // #include "codegen/ast-to-llvm.h"
 #include "codegen/ast-to-object.h"
-#include "codegen/ast-to-output.h"
+#include "codegen/ast-to-stdout.h"
 
 #include "io.h"
 #include "parser.h"
@@ -34,32 +34,32 @@ extern std::string OUTPUT_FILE;
 extern bool INPUT_FROM_STDIN;
 
 /**
- * @brief
- * @param count
+ * @brief Open the Arx shell.
+ * @param count An internal value from CLI11.
  *
  */
-auto main_open_shell(int count) -> void {
+auto main_open_shell(__attribute__((unused)) int count) -> void {
   INPUT_FROM_STDIN = true;
   open_shell();
   exit(0);
 }
 
 /**
- * @brief
- * @param count
+ * @brief Show the Arx version number.
+ * @param count An internal value from CLI11.
  *
  */
-auto main_show_version(int count) {
+auto main_show_version(__attribute__((unused)) int count) -> void {
   load_input_to_buffer();
   show_version();
   exit(0);
 }
 
 /**
- * @brief
- *
+ * @brief Show the AST for the given source.
+ * @param count An internal value from CLI11.
  */
-auto main_show_ast(int count) -> void {
+auto main_show_ast(__attribute__((unused)) int count) -> void {
   load_input_to_buffer();
   TreeAST* ast = Parser::parse();
   print_ast(ast);
@@ -67,7 +67,7 @@ auto main_show_ast(int count) -> void {
 }
 
 /**
- * @brief
+ * @brief Compile the given source code.
  *
  */
 auto main_compile() -> void {
@@ -78,10 +78,10 @@ auto main_compile() -> void {
 }
 
 /**
- * @brief
- * @param argc
- * @param argv
- * @return
+ * @brief The main function.
+ * @param argc used by CLI11.
+ * @param argv used by CLI11.
+ * @return exit code.
  *
  */
 auto main(int argc, const char* argv[]) -> int {
diff --git a/src/parser.cpp b/src/parser.cpp
index 71ebae7..8100aa4 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -76,7 +76,7 @@ void ExprAST::accept(Visitor* visitor) {
 
 /**
  * @brief Get the precedence of the pending binary operator token.
- * @return
+ * @return The token precedence.
  *
  */
 auto Parser::GetTokPrecedence() -> int {
@@ -93,18 +93,18 @@ auto Parser::GetTokPrecedence() -> int {
 }
 
 /**
- * @brief
+ * @brief Parse the number expression.
  * @return
  * numberexpr ::= number
  */
 std::unique_ptr<NumberExprAST> Parser::ParseNumberExpr() {
   auto Result = std::make_unique<NumberExprAST>(Lexer::NumVal);
   Lexer::getNextToken();  // consume the number
-  return std::move(Result);
+  return Result;
 }
 
 /**
- * @brief
+ * @brief Parse the parenthesis expression.
  * @return
  * parenexpr ::= '(' expression ')'
  */
@@ -123,7 +123,7 @@ std::unique_ptr<ExprAST> Parser::ParseParenExpr() {
 }
 
 /**
- * @brief
+ * @brief Parse the identifier expression.
  * @return
  * identifierexpr
  *   ::= identifier
@@ -170,7 +170,7 @@ std::unique_ptr<ExprAST> Parser::ParseIdentifierExpr() {
 }
 
 /**
- * @brief
+ * @brief Parse the `if` expression.
  * @return
  * ifexpr ::= 'if' expression 'then' expression 'else' expression
  */
@@ -222,7 +222,7 @@ std::unique_ptr<IfExprAST> Parser::ParseIfExpr() {
 }
 
 /**
- * @brief
+ * @brief Parse the `for` expression.
  * @return
  * forexpr ::= 'for' identifier '=' expr ',' expr (',' expr)? 'in' expression
  */
@@ -284,7 +284,7 @@ std::unique_ptr<ForExprAST> Parser::ParseForExpr() {
 }
 
 /**
- * @brief
+ * @brief Parse the `var` declaration expression.
  * @return
  * varexpr ::= 'var' identifier ('=' expression)?
  *                    (',' identifier ('=' expression)?)* 'in' expression
@@ -343,7 +343,7 @@ std::unique_ptr<VarExprAST> Parser::ParseVarExpr() {
 }
 
 /**
- * @brief
+ * @brief Parse the primary expression.
  * @return
  * primary
  *   ::= identifierexpr
@@ -382,7 +382,7 @@ std::unique_ptr<ExprAST> Parser::ParsePrimary() {
 }
 
 /**
- * @brief
+ * @brief Parse a unary expression.
  * @return
  * unary
  *   ::= primary
@@ -405,9 +405,9 @@ std::unique_ptr<ExprAST> Parser::ParseUnary() {
 }
 
 /**
- * @brief
- * @param ExprPrec
- * @param LHS
+ * @brief Parse a binary expression.
+ * @param ExprPrec Expression Pression (deprecated)
+ * @param LHS Left hand side Expression
  * @return
  * binoprhs
  *   ::= ('+' unary)*
@@ -452,7 +452,7 @@ std::unique_ptr<ExprAST> Parser::ParseBinOpRHS(
 }
 
 /**
- * @brief
+ * @brief Parse an expression.
  * @return
  * expression
  *   ::= unary binoprhs
@@ -468,7 +468,7 @@ std::unique_ptr<ExprAST> Parser::ParseExpression() {
 }
 
 /**
- * @brief
+ * @brief Parse an extern prototype expression.
  * @return
  * prototype
  *   ::= id '(' id* ')'
@@ -511,7 +511,7 @@ std::unique_ptr<PrototypeAST> Parser::ParseExternPrototype() {
 }
 
 /**
- * @brief
+ * @brief Parse the prototype expression.
  * @return
  * prototype
  *   ::= id '(' id* ')'
@@ -561,7 +561,7 @@ std::unique_ptr<PrototypeAST> Parser::ParsePrototype() {
 }
 
 /**
- * @brief
+ * @brief Parse the function definition expression.
  * @return
  * definition ::= 'function' prototype expression
  */
@@ -579,7 +579,7 @@ std::unique_ptr<FunctionAST> Parser::ParseDefinition() {
 }
 
 /**
- * @brief
+ * @brief Parse the top level expression.
  * @return
  * toplevelexpr ::= expression
  */
@@ -595,7 +595,7 @@ std::unique_ptr<FunctionAST> Parser::ParseTopLevelExpr() {
 }
 
 /**
- * @brief
+ * @brief Parse the extern expression;
  * @return
  * external ::= 'extern' prototype
  */
@@ -621,13 +621,13 @@ auto Parser::parse() -> TreeAST* {
         // ignore top-level semicolons.
         break;
       case tok_function:
-        ast->nodes.emplace_back(std::move(Parser::ParseDefinition()));
+        ast->nodes.emplace_back(Parser::ParseDefinition());
         break;
       case tok_extern:
-        ast->nodes.emplace_back(std::move(Parser::ParseExtern()));
+        ast->nodes.emplace_back(Parser::ParseExtern());
         break;
       default:
-        ast->nodes.emplace_back(std::move(Parser::ParseTopLevelExpr()));
+        ast->nodes.emplace_back(Parser::ParseTopLevelExpr());
         break;
     }
   }
diff --git a/src/parser.h b/src/parser.h
index 4e55c87..358aa7e 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -58,7 +58,7 @@ class ExprAST {
   SourceLocation Loc;
 
   /**
-   * @param Loc
+   * @param Loc The token location
    */
   ExprAST(SourceLocation Loc = Lexer::CurLoc) : Loc(Loc) {
     this->kind = ExprKind::GenericKind;
@@ -84,10 +84,6 @@ class ExprAST {
  */
 class NumberExprAST : public ExprAST {
  public:
-  /**
-   *
-   * @return
-   */
   double Val;
 
   NumberExprAST(double Val) : Val(Val) {
@@ -104,8 +100,8 @@ class VariableExprAST : public ExprAST {
   std::string Name;
 
   /**
-   * @param Loc
-   * @param Name
+   * @param Loc The token location
+   * @param Name The variable name
    */
   VariableExprAST(SourceLocation Loc, std::string Name)
       : ExprAST(Loc), Name(std::move(Name)) {
@@ -127,8 +123,8 @@ class UnaryExprAST : public ExprAST {
   std::unique_ptr<ExprAST> Operand;
 
   /**
-   * @param Opcode
-   * @param Operand
+   * @param Opcode The operator code
+   * @param Operand The operand expression
    */
   UnaryExprAST(char Opcode, std::unique_ptr<ExprAST> Operand)
       : Opcode(Opcode), Operand(std::move(Operand)) {
@@ -146,10 +142,10 @@ class BinaryExprAST : public ExprAST {
   std::unique_ptr<ExprAST> LHS, RHS;
 
   /**
-   * @param Loc
-   * @param Op
-   * @param LHS
-   * @param RHS
+   * @param Loc The token location
+   * @param Op The operator
+   * @param LHS The left hand side expression
+   * @param RHS The right hand side expression
    */
   BinaryExprAST(
     SourceLocation Loc,
@@ -171,9 +167,9 @@ class CallExprAST : public ExprAST {
   std::vector<std::unique_ptr<ExprAST>> Args;
 
   /**
-   * @param Loc
-   * @param Callee
-   * @param Args
+   * @param Loc The token location
+   * @param Callee The function name
+   * @param Args The function arguments
    */
   CallExprAST(
     SourceLocation Loc,
@@ -193,10 +189,10 @@ class IfExprAST : public ExprAST {
   std::unique_ptr<ExprAST> Cond, Then, Else;
 
   /**
-   * @param Loc
-   * @param Cond
-   * @param Then
-   * @param Else
+   * @param Loc The token location
+   * @param Cond The conditional expression
+   * @param Then The `then` branch expression
+   * @param Else The `else` branch expression
    */
   IfExprAST(
     SourceLocation Loc,
@@ -222,11 +218,11 @@ class ForExprAST : public ExprAST {
   std::unique_ptr<ExprAST> Start, End, Step, Body;
 
   /**
-   * @param VarName
-   * @param Start
-   * @param End
-   * @param Step
-   * @param Body
+   * @param VarName The variable name
+   * @param Start The `start` parameter for the loop
+   * @param End The `end` parameter for the loop
+   * @param Step The incremental value for the loop
+   * @param Body The body of the for the loop.
    */
   ForExprAST(
     std::string VarName,
@@ -254,8 +250,8 @@ class VarExprAST : public ExprAST {
   std::unique_ptr<ExprAST> Body;
 
   /**
-   * @param VarNames
-   * @param Body
+   * @param VarNames Variable names
+   * @param Body Body of the variables
    */
   VarExprAST(
     std::vector<std::pair<std::string, std::unique_ptr<ExprAST>>> VarNames,
@@ -278,9 +274,9 @@ class PrototypeAST : public ExprAST {
   int Line;
 
   /**
-   * @param Loc
-   * @param Name
-   * @param Args
+   * @param Loc The token location
+   * @param Name The prototype name
+   * @param Args The prototype arguments
    */
   PrototypeAST(
     SourceLocation Loc, std::string Name, std::vector<VariableExprAST*> Args)
@@ -308,8 +304,8 @@ class FunctionAST : public ExprAST {
   std::unique_ptr<ExprAST> Body;
 
   /**
-   * @param Proto
-   * @param Body
+   * @param Proto The function prototype
+   * @param Body The function body
    */
   FunctionAST(
     std::unique_ptr<PrototypeAST> Proto, std::unique_ptr<ExprAST> Body)
diff --git a/src/utils.cpp b/src/utils.cpp
index 1f855d7..0cea0a4 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -8,10 +8,10 @@
 extern std::string ARX_VERSION;
 
 /**
- * @brief
- * @param O
- * @param size
- * @return
+ * @brief Ident the output.
+ * @param O Buffer used by the indentation.
+ * @param size Buffer size.
+ * @return a buffer with the indentation with given width.
  *
  */
 auto indent(llvm::raw_ostream& O, int size) -> llvm::raw_ostream& {
@@ -19,7 +19,7 @@ auto indent(llvm::raw_ostream& O, int size) -> llvm::raw_ostream& {
 }
 
 /**
- * @brief
+ * @brief Show the Arx version.
  *
  */
 auto show_version() -> void {
diff --git a/tests/main-objects/print-star.cpp b/tests/main-objects/print-star.cpp
index a600b06..5e99b77 100644
--- a/tests/main-objects/print-star.cpp
+++ b/tests/main-objects/print-star.cpp
@@ -5,7 +5,7 @@ double print_star(double);
 }
 
 extern "C" auto putchard(double X) -> double {
-  fputc((char) X, stderr);
+  fputc(static_cast<char>(X), stderr);
   return 0;
 }