build: remove dependency on fmt library, using std::format instead (#929)

This bumps the standard version to C++23, so that the `formattable`
concept becomes available.

This removes the color support from `diff.cpp`, since that is not
available in std::format.

Author: mizvekov

.github/workflows/ci.yml

@@ -288,26 +288,6 @@ jobs:
           run-tests: false
           trace-commands: true
 
-      - name: Install Fmt
-        uses: alandefreitas/cpp-actions/cmake-workflow@v1.8.10
-        with:
-          source-dir: ../third-party/fmt
-          git-repository: https://github.com/fmtlib/fmt
-          git-tag: 10.2.1
-          build-dir: ${sourceDir}/build
-          cc: ${{ steps.setup-cpp.outputs.cc }}
-          cxx: ${{ steps.setup-cpp.outputs.cxx }}
-          ccflags: ${{ matrix.ccflags }}
-          cxxflags: ${{ matrix.cxxflags }}
-          build-type: ${{ matrix.build-type }}
-          extra-args: |
-            -D FMT_DOC=OFF
-            -D FMT_TEST=OFF
-          install: true
-          install-prefix: ${sourceDir}/install
-          run-tests: false
-          trace-commands: true
-
       - name: Install Libxml2
         uses: alandefreitas/cpp-actions/cmake-workflow@v1.8.10
         if: matrix.compiler == 'msvc'
@@ -385,7 +365,6 @@ jobs:
             -D Clang_ROOT=../third-party/llvm-project/install
             -D duktape_ROOT=../third-party/duktape/install
             -D Duktape_ROOT=../third-party/duktape/install
-            -D fmt_ROOT=../third-party/fmt/install
             ${{ runner.os == 'Windows' && '-D libxml2_ROOT=../third-party/libxml2/install' || '' }}
             ${{ runner.os == 'Windows' && '-D LibXml2_ROOT=../third-party/libxml2/install' || '' }}
           export-compile-commands: true

CMakeLists.txt

@@ -118,9 +118,6 @@ llvm_map_components_to_libnames(llvm_libs all)
 string(REGEX REPLACE " /W[0-4]" "" CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
 string(REGEX REPLACE " /W[0-4]" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
 
-# fmt
-find_package(fmt REQUIRED CONFIG)
-
 # Duktape
 find_package(duktape CONFIG)
 if (NOT DUKTAPE_FOUND)
@@ -213,7 +210,7 @@ list(APPEND LIB_SOURCES
     ${CMAKE_CURRENT_BINARY_DIR}/src/lib/Lib/PublicSettings.cpp
 )
 add_library(mrdocs-core ${LIB_SOURCES})
-target_compile_features(mrdocs-core PUBLIC cxx_std_20)
+target_compile_features(mrdocs-core PUBLIC cxx_std_23)
 target_include_directories(mrdocs-core
     PUBLIC
     "$<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include/>"
@@ -233,7 +230,6 @@ target_compile_definitions(
 # Dependencies
 target_include_directories(mrdocs-core SYSTEM PUBLIC ${LLVM_INCLUDE_DIRS})
 target_include_directories(mrdocs-core SYSTEM PUBLIC ${CLANG_INCLUDE_DIRS})
-target_link_libraries(mrdocs-core PUBLIC fmt::fmt)
 target_include_directories(mrdocs-core SYSTEM PRIVATE ${DUKTAPE_INCLUDE_DIRS})
 target_link_libraries(mrdocs-core PRIVATE ${DUKTAPE_LIBRARY})
 

docs/modules/ROOT/pages/install.adoc

@@ -125,27 +125,6 @@ These instructions assume all dependencies are installed in the `third-party` di
 Feel free to install them anywhere you want and adjust the main MrDocs configuration command later.
 ====
 
-[#install-fmt]
-=== Fmt
-
-MrDocs uses the `fmt` library for formatting strings.
-From the `third-party` directory, you can clone the `fmt` repository and install it with the following commands:
-
-[source,bash]
-----
-git clone https://github.com/fmtlib/fmt --branch 10.2.1 --depth 1 <.>
-cd fmt
-cmake -S . -B ./build -DCMAKE_BUILD_TYPE=Release -D FMT_DOC=OFF -D FMT_TEST=OFF <.>
-cmake --build ./build --config Release <.>
-cmake --install ./build --prefix ./install <.>
-cd ..
-----
-
-<.> Shallow clones the fmt repository.
-<.> Configure the fmt library with CMake, excluding the documentation and tests.
-<.> Builds the fmt library in the `build` directory.
-<.> Installs the fmt library in the `install` directory.
-
 [IMPORTANT]
 ====
 All instructions in this document assume you are using a CMake version above 3.26.
@@ -385,7 +364,7 @@ cd ../..
 
 The MrDocs repository also includes a `CMakePresets.json` file that contains the parameters to configure MrDocs with CMake.
 
-To specify the installation directories, you can use the `LLVM_ROOT`, `DUKTAPE_ROOT`, `FMT_ROOT`, and `LIBXML2_ROOT` environment variables.
+To specify the installation directories, you can use the `LLVM_ROOT`, `DUKTAPE_ROOT`, and `LIBXML2_ROOT` environment variables.
 To specify a generator (`-G`) and platform name (`-A`), you can use the `CMAKE_GENERATOR` and `CMAKE_GENERATOR_PLATFORM` environment variables.
 
 You can also customize the presets by duplicating and editing the `CMakeUserPresets.json.example` file in the `mrdocs` directory.

include/mrdocs/Dom/Object.ipp

@@ -149,14 +149,15 @@ Object::visit(F&& fn) const
 //------------------------------------------------
 
 template<>
-struct fmt::formatter<clang::mrdocs::dom::Object>
-    : fmt::formatter<std::string>
+struct std::formatter<clang::mrdocs::dom::Object>
+    : std::formatter<std::string>
 {
+    template <class FmtContext>
     auto format(
         clang::mrdocs::dom::Object const& value,
-        fmt::format_context& ctx) const
+        FmtContext& ctx) const
     {
-        return fmt::formatter<std::string>::format(
+        return std::formatter<std::string>::format(
             toString(value), ctx);
     }
 };

include/mrdocs/Dom/String.hpp

@@ -11,9 +11,9 @@
 #ifndef MRDOCS_API_DOM_STRING_HPP
 #define MRDOCS_API_DOM_STRING_HPP
 
+#include <format>
 #include <mrdocs/Platform.hpp>
 #include <mrdocs/Support/String.hpp>
-#include <fmt/format.h>
 
 namespace clang {
 namespace mrdocs {
@@ -341,17 +341,13 @@ class MRDOCS_DECL
 
 //------------------------------------------------
 
-template<>
-struct fmt::formatter<clang::mrdocs::dom::String>
-    : fmt::formatter<std::string_view>
-{
-    auto format(
-        clang::mrdocs::dom::String const& value,
-        fmt::format_context& ctx) const
-    {
-        return fmt::formatter<std::string_view>::format(
-            value.get(), ctx);
-    }
+template <>
+struct std::formatter<clang::mrdocs::dom::String>
+    : std::formatter<std::string_view> {
+  template <class FmtContext>
+  auto format(clang::mrdocs::dom::String const &value, FmtContext &ctx) const {
+    return std::formatter<std::string_view>::format(value.get(), ctx);
+  }
 };
 
 #endif

include/mrdocs/Dom/Value.hpp

@@ -11,18 +11,19 @@
 #ifndef MRDOCS_API_DOM_VALUE_HPP
 #define MRDOCS_API_DOM_VALUE_HPP
 
-#include <mrdocs/Platform.hpp>
+#include <charconv>
+#include <compare>
+#include <format>
+#include <mrdocs/ADT/Optional.hpp>
 #include <mrdocs/Dom/Array.hpp>
-#include <mrdocs/Dom/Kind.hpp>
 #include <mrdocs/Dom/Function.hpp>
+#include <mrdocs/Dom/Kind.hpp>
 #include <mrdocs/Dom/Object.hpp>
 #include <mrdocs/Dom/String.hpp>
-#include <mrdocs/ADT/Optional.hpp>
+#include <mrdocs/Platform.hpp>
 #include <mrdocs/Support/Error.hpp>
 #include <optional> // BAD
 #include <string>
-#include <charconv>
-#include <compare>
 
 namespace clang {
 namespace mrdocs {
@@ -849,17 +850,13 @@ safeString(SV const& str) {
 
 //------------------------------------------------
 
-template<>
-struct fmt::formatter<clang::mrdocs::dom::Value>
-    : public fmt::formatter<std::string>
-{
-    auto format(
-        clang::mrdocs::dom::Value const& value,
-        fmt::format_context& ctx) const
-    {
-        return fmt::formatter<std::string>::format(
-            toString(value), ctx);
-    }
+template <>
+struct std::formatter<clang::mrdocs::dom::Value>
+    : public std::formatter<std::string> {
+  template <class FmtContext>
+  auto format(clang::mrdocs::dom::Value const &value, FmtContext &ctx) const {
+    return std::formatter<std::string>::format(toString(value), ctx);
+  }
 };
 
 #endif

include/mrdocs/Metadata/Javadoc.hpp

@@ -13,15 +13,16 @@
 #ifndef MRDOCS_API_METADATA_JAVADOC_HPP
 #define MRDOCS_API_METADATA_JAVADOC_HPP
 
-#include <mrdocs/Platform.hpp>
-#include <mrdocs/Metadata/SymbolID.hpp>
-#include <mrdocs/Support/Visitor.hpp>
-#include <mrdocs/Support/Concepts.hpp>
+#include <algorithm>
+#include <memory>
 #include <mrdocs/ADT/Polymorphic.hpp>
-#include <mrdocs/Dom/String.hpp>
-#include <mrdocs/Dom/LazyObject.hpp>
 #include <mrdocs/Dom/LazyArray.hpp>
-#include <memory>
+#include <mrdocs/Dom/LazyObject.hpp>
+#include <mrdocs/Dom/String.hpp>
+#include <mrdocs/Metadata/SymbolID.hpp>
+#include <mrdocs/Platform.hpp>
+#include <mrdocs/Support/Concepts.hpp>
+#include <mrdocs/Support/Visitor.hpp>
 #include <string>
 #include <type_traits>
 #include <utility>

include/mrdocs/Support/Error.hpp

@@ -12,17 +12,18 @@
 #ifndef MRDOCS_API_SUPPORT_ERROR_HPP
 #define MRDOCS_API_SUPPORT_ERROR_HPP
 
-#include <mrdocs/Platform.hpp>
-#include <mrdocs/Support/source_location.hpp>
-#include <fmt/format.h>
 #include <exception>
+#include <format>
+#include <functional>
 #include <memory>
+#include <mrdocs/Platform.hpp>
+#include <mrdocs/Support/source_location.hpp>
 #include <string>
 #include <string_view>
+#include <system_error>
 #include <type_traits>
 #include <utility>
 #include <vector>
-#include <functional>
 
 namespace clang::mrdocs {
 
@@ -256,28 +257,20 @@ struct std::hash<::clang::mrdocs::Error>
     }
 };
 
-template<>
-struct fmt::formatter<clang::mrdocs::Error>
-    : fmt::formatter<std::string_view>
-{
-    auto format(
-        clang::mrdocs::Error const& err,
-        fmt::format_context& ctx) const
-    {
-        return fmt::formatter<std::string_view>::format(err.message(), ctx);
-    }
+template <>
+struct std::formatter<clang::mrdocs::Error> : std::formatter<std::string_view> {
+  template <class FmtContext>
+  auto format(clang::mrdocs::Error const &err, FmtContext &ctx) const {
+    return std::formatter<std::string_view>::format(err.message(), ctx);
+  }
 };
 
-template<>
-struct fmt::formatter<std::error_code>
-    : fmt::formatter<std::string_view>
-{
-    auto format(
-        std::error_code const& ec,
-        fmt::format_context& ctx) const
-    {
-        return fmt::formatter<std::string_view>::format(ec.message(), ctx);
-    }
+template <>
+struct std::formatter<std::error_code> : std::formatter<std::string_view> {
+  template <class FmtContext>
+  auto format(std::error_code const &ec, FmtContext &ctx) const {
+    return std::formatter<std::string_view>::format(ec.message(), ctx);
+  }
 };
 
 namespace clang::mrdocs {
@@ -353,9 +346,8 @@ formatError(
     Args&&... args)
 {
     std::string s;
-    fmt::vformat_to(
-        std::back_inserter(s),
-        fs.fs, fmt::make_format_args(args...));
+    std::vformat_to(std::back_inserter(s), fs.fs,
+                    std::make_format_args(args...));
     return Error(std::move(s), fs.loc);
 }
 

include/mrdocs/Support/Expected.hpp

@@ -12,19 +12,18 @@
 #ifndef MRDOCS_API_SUPPORT_EXPECTED_HPP
 #define MRDOCS_API_SUPPORT_EXPECTED_HPP
 
-#include <mrdocs/Platform.hpp>
-#include <mrdocs/Support/source_location.hpp>
-#include <mrdocs/Support/Error.hpp>
-#include <fmt/format.h>
 #include <exception>
+#include <functional>
 #include <iterator>
 #include <memory>
+#include <mrdocs/Platform.hpp>
+#include <mrdocs/Support/Error.hpp>
+#include <mrdocs/Support/source_location.hpp>
 #include <string>
 #include <string_view>
 #include <type_traits>
 #include <utility>
 #include <vector>
-#include <functional>
 
 namespace clang::mrdocs {
 

include/mrdocs/Support/Handlebars.hpp

@@ -11,14 +11,15 @@
 #ifndef MRDOCS_TOOL_SUPPORT_PATH_HPP
 #define MRDOCS_TOOL_SUPPORT_PATH_HPP
 
-#include <mrdocs/Support/String.hpp>
+#include <format>
+#include <functional>
 #include <mrdocs/Dom.hpp>
+#include <mrdocs/Support/String.hpp>
 #include <string_view>
-#include <unordered_map>
-#include <functional>
 #include <type_traits>
-#include <vector>
+#include <unordered_map>
 #include <variant>
+#include <vector>
 
 namespace clang {
 namespace mrdocs {
@@ -45,15 +46,10 @@ struct HandlebarsError
     HandlebarsError(std::string_view msg)
         : std::runtime_error(std::string(msg)) {}
 
-    HandlebarsError(
-        std::string_view msg,
-        std::size_t line_,
-        std::size_t column_,
-        std::size_t pos_)
-        : std::runtime_error(fmt::format("{} - {}:{}", msg, line_, column_))
-        , line(line_)
-        , column(column_)
-        , pos(pos_) {}
+    HandlebarsError(std::string_view msg, std::size_t line_,
+                    std::size_t column_, std::size_t pos_)
+        : std::runtime_error(std::format("{} - {}:{}", msg, line_, column_)),
+          line(line_), column(column_), pos(pos_) {}
 };
 
 namespace detail {
@@ -218,9 +214,9 @@ class MRDOCS_DECL OutputRef
         @return A reference to this object
      */
     template <class T>
-      requires fmt::is_formattable<T>::value
+      requires std::formattable<T, char>
     friend OutputRef &operator<<(OutputRef &os, T v) {
-      std::string s = fmt::format("{}", v);
+      std::string s = std::format("{}", v);
       return os.write_impl(s);
     }