gn: migrate to Conan v2

recipes/gn/all/conanfile.py

@@ -1,128 +1,153 @@
-from conans import ConanFile, tools
-from conans.errors import ConanInvalidConfiguration
-from contextlib import contextmanager
-import conan.tools.files as tools_files
-import conan.tools.scm as tools_scm
 import os
+import shutil
 import sys
 import textwrap
 import time
 
-required_conan_version = ">=1.46.0"
+from conan import ConanFile
+from conan.errors import ConanInvalidConfiguration
+from conan.tools.apple import is_apple_os, XCRun
+from conan.tools.build import check_min_cppstd
+from conan.tools.env import VirtualBuildEnv, Environment
+from conan.tools.files import chdir, copy, get, load, save, replace_in_file
+from conan.tools.layout import basic_layout
+from conan.tools.microsoft import is_msvc, VCVars
+from conan.tools.scm import Version
+
+required_conan_version = ">=1.47.0"
 
 
 class GnConan(ConanFile):
     name = "gn"
     description = "GN is a meta-build system that generates build files for Ninja."
-    url = "https://github.com/conan-io/conan-center-index"
-    topics = ("gn", "build", "system", "ninja")
     license = "BSD-3-Clause"
+    url = "https://github.com/conan-io/conan-center-index"
     homepage = "https://gn.googlesource.com/"
+    topics = ("build system", "ninja")
+
+    package_type = "application"
     settings = "os", "arch", "compiler", "build_type"
 
-    @property
-    def _source_subfolder(self):
-        return "source_subfolder"
+    def layout(self):
+        basic_layout(self, src_folder="src")
+
+    def package_id(self):
+        del self.info.settings.compiler
 
     @property
     def _minimum_compiler_version_supporting_cxx17(self):
         return {
             "Visual Studio": 15,
+            "msvc": 191,
             "gcc": 7,
             "clang": 4,
             "apple-clang": 10,
         }.get(str(self.settings.compiler))
 
     def validate(self):
         if self.settings.compiler.cppstd:
-            tools.check_min_cppstd(self, 17)
+            check_min_cppstd(self, 17)
         else:
             if self._minimum_compiler_version_supporting_cxx17:
-                if tools_scm.Version(self.settings.compiler.version) < self._minimum_compiler_version_supporting_cxx17:
+                if Version(self.settings.compiler.version) < self._minimum_compiler_version_supporting_cxx17:
                     raise ConanInvalidConfiguration("gn requires a compiler supporting c++17")
             else:
-                self.output.warn("gn recipe does not recognize the compiler. gn requires a compiler supporting c++17. Assuming it does.")
-
-    def package_id(self):
-        del self.info.settings.compiler
-
-    def source(self):
-        tools_files.get(self, **self.conan_data["sources"][self.version], destination=self._source_subfolder)
+                self.output.warning(
+                    "gn recipe does not recognize the compiler. gn requires a compiler supporting c++17."
+                    " Assuming it does."
+                )
 
     def build_requirements(self):
         # FIXME: add cpython build requirements for `build/gen.py`.
-        self.build_requires("ninja/1.10.2")
+        self.build_requires("ninja/1.11.1")
 
-    @contextmanager
-    def _build_context(self):
-        if self.settings.compiler == "Visual Studio":
-            with tools.vcvars(self.settings):
-                yield
-        else:
-            compiler_defaults = {}
-            if self.settings.compiler == "gcc":
-                compiler_defaults = {
-                    "CC": "gcc",
-                    "CXX": "g++",
-                    "AR": "ar",
-                    "LD": "g++",
-                }
-            elif self.settings.compiler == "clang":
-                compiler_defaults = {
-                    "CC": "clang",
-                    "CXX": "clang++",
-                    "AR": "ar",
-                    "LD": "clang++",
-                }
-            env = {}
-            for k in ("CC", "CXX", "AR", "LD"):
-                v = tools.get_env(k, compiler_defaults.get(k, None))
-                if v:
-                    env[k] = v
-            with tools.environment_append(env):
-                yield
-
-    @staticmethod
-    def _to_gn_platform(os_, compiler):
-        if tools.is_apple_os(os_):
+    def source(self):
+        get(self, **self.conan_data["sources"][self.version])
+
+    @property
+    def _gn_platform(self):
+        if is_apple_os(self):
             return "darwin"
-        if compiler == "Visual Studio":
+        if is_msvc(self):
             return "msvc"
         # Assume gn knows about the os
-        return str(os_).lower()
+        return str(self.settings.os).lower()
+
+    @property
+    def _cxx(self):
+        compilers_by_conf = self.conf.get("tools.build:compiler_executables", default={}, check_type=dict)
+        cxx = compilers_by_conf.get("cpp") or VirtualBuildEnv(self).vars().get("CXX")
+        if cxx:
+            return cxx
+        if self.settings.compiler == "apple-clang":
+            return XCRun(self).cxx
+        compiler_version = self.settings.compiler.version
+        major = Version(compiler_version).major
+        if self.settings.compiler == "gcc":
+            return shutil.which(f"g++-{compiler_version}") or shutil.which(f"g++-{major}") or shutil.which("g++") or ""
+        if self.settings.compiler == "clang":
+            return shutil.which(f"clang++-{compiler_version}") or shutil.which(f"clang++-{major}") or shutil.which("clang++") or ""
+        return ""
+
+    def generate(self):
+        env = VirtualBuildEnv(self)
+        env.generate()
+
+        # Make sure CXX env var is set, otherwise gn defaults it to clang++
+        # https://gn.googlesource.com/gn/+/refs/heads/main/build/gen.py#386
+        env = Environment()
+        env.define("CXX", self._cxx)
+        env.vars(self).save_script("conanbuild_gn")
+
+        if is_msvc(self):
+            vcvars = VCVars(self)
+            vcvars.generate()
+
+        configure_args = [
+            "--no-last-commit-position",
+            f"--host={self._gn_platform}",
+        ]
+        if self.settings.build_type in ["Debug", "RelWithDebInfo"]:
+            configure_args.append("-d")
+        save(self, os.path.join(self.source_folder, "configure_args"), " ".join(configure_args))
 
     def build(self):
-        with tools.chdir(self._source_subfolder):
-            with self._build_context():
-                # Generate dummy header to be able to run `build/ben.py` with `--no-last-commit-position`. This allows running the script without the tree having to be a git checkout.
-                tools.save(os.path.join("src", "gn", "last_commit_position.h"),
-                           textwrap.dedent("""\
-                                #pragma once
-                                #define LAST_COMMIT_POSITION "1"
-                                #define LAST_COMMIT_POSITION_NUM 1
-                                """))
-                conf_args = [
-                    "--no-last-commit-position",
-                    "--host={}".format(self._to_gn_platform(self.settings.os, self.settings.compiler)),
-                ]
-                if self.settings.build_type == "Debug":
-                    conf_args.append("-d")
-                self.run("{} build/gen.py {}".format(sys.executable, " ".join(conf_args)), run_environment=True)
-                # Try sleeping one second to avoid time skew of the generated ninja.build file (and having to re-run build/gen.py)
-                time.sleep(1)
-                build_args = [
-                    "-C", "out",
-                    "-j{}".format(tools.cpu_count()),
-                ]
-                self.run("ninja {}".format(" ".join(build_args)), run_environment=True)
+        with chdir(self, self.source_folder):
+            # Generate dummy header to be able to run `build/gen.py` with `--no-last-commit-position`.
+            # This allows running the script without the tree having to be a git checkout.
+            save(self, os.path.join(self.source_folder, "src", "gn", "last_commit_position.h"),
+                textwrap.dedent("""\
+                    #pragma once
+                    #define LAST_COMMIT_POSITION "1"
+                    #define LAST_COMMIT_POSITION_NUM 1
+                    """),
+            )
+
+            # Disable GenerateLastCommitPosition()
+            replace_in_file(self, os.path.join(self.source_folder, "build/gen.py"),
+                            "def GenerateLastCommitPosition(host, header):",
+                            "def GenerateLastCommitPosition(host, header):\n  return")
+
+            self.run(f"{sys.executable} build/gen.py " + load(self, "configure_args"))
+            self.run(f"ninja -C out -j{os.cpu_count()} -v")
 
     def package(self):
-        self.copy("LICENSE", src=self._source_subfolder, dst="licenses")
-        self.copy("gn", src=os.path.join(self._source_subfolder, "out"), dst="bin")
-        self.copy("gn.exe", src=os.path.join(self._source_subfolder, "out"), dst="bin")
+        copy(self, "LICENSE", src=self.source_folder, dst=os.path.join(self.package_folder, "licenses"))
+        if self.settings.os == "Windows":
+            copy(self, "gn.exe",
+                 src=os.path.join(self.source_folder, "out"),
+                 dst=os.path.join(self.package_folder, "bin"))
+        else:
+            copy(self, "gn",
+                 src=os.path.join(self.source_folder, "out"),
+                 dst=os.path.join(self.package_folder, "bin"))
 
     def package_info(self):
+        self.cpp_info.includedirs = []
+        self.cpp_info.frameworkdirs = []
+        self.cpp_info.libdirs = []
+        self.cpp_info.resdirs = []
+
         bin_path = os.path.join(self.package_folder, "bin")
-        self.output.info("Appending PATH environment variable: {}".format(bin_path))
+        self.output.info(f"Appending PATH environment variable: {bin_path}")
         self.env_info.PATH.append(bin_path)
-        self.cpp_info.includedirs = []

recipes/gn/all/test_package/conanfile.py

@@ -1,46 +1,28 @@
-from conans import ConanFile, CMake, tools
-from contextlib import contextmanager
 import os
 
+from conan import ConanFile
+from conan.tools.apple import is_apple_os
+from conan.tools.build import can_run, cross_building
+from conan.tools.env import VirtualRunEnv, VirtualBuildEnv
+from conan.tools.layout import basic_layout
+from conan.tools.microsoft import unix_path
+
 
 class TestPackageConan(ConanFile):
-    settings = "os", "compiler", "build_type", "arch"
+    settings = "os", "arch", "compiler", "build_type"
+    generators = "VCVars"
+    test_type = "explicit"
 
     def build_requirements(self):
-        self.build_requires("ninja/1.10.2")
+        self.tool_requires(self.tested_reference_str)
+        self.tool_requires("ninja/1.11.1")
 
-    @contextmanager
-    def _build_context(self):
-        if self.settings.compiler == "Visual Studio":
-            with tools.vcvars(self.settings):
-                yield
-        else:
-            compiler_defaults = {}
-            if self.settings.compiler == "gcc":
-                compiler_defaults = {
-                    "CC": "gcc",
-                    "CXX": "g++",
-                    "AR": "ar",
-                    "LD": "g++",
-                }
-            elif self.settings.compiler in ("apple-clang", "clang"):
-                compiler_defaults = {
-                    "CC": "clang",
-                    "CXX": "clang++",
-                    "AR": "ar",
-                    "LD": "clang++",
-                }
-            env = {}
-            for k in ("CC", "CXX", "AR", "LD"):
-                v = tools.get_env(k, compiler_defaults.get(k, None))
-                if v:
-                    env[k] = v
-            with tools.environment_append(env):
-                yield
+    def layout(self):
+        basic_layout(self)
 
     @property
     def _target_os(self):
-        if tools.is_apple_os(self.settings.os):
+        if is_apple_os(self):
             return "mac"
         # Assume gn knows about the os
         return {
@@ -53,17 +35,22 @@ def _target_cpu(self):
             "x86_64": "x64",
         }.get(str(self.settings.arch), str(self.settings.arch))
 
+    def generate(self):
+        VirtualBuildEnv(self).generate()
+        VirtualRunEnv(self).generate(scope="run")
+        VirtualRunEnv(self).generate(scope="build")
+
     def build(self):
-        if not tools.cross_building(self.settings):
-            with tools.chdir(self.source_folder):
-                gn_args = [
-                    os.path.relpath(os.path.join(self.build_folder, "bin"), os.getcwd()).replace("\\", "/"),
-                    "--args=\"target_os=\\\"{os_}\\\" target_cpu=\\\"{cpu}\\\"\"".format(os_=self._target_os, cpu=self._target_cpu),
-                ]
-                self.run("gn gen {}".format(" ".join(gn_args)), run_environment=True)
-            with self._build_context():
-                self.run("ninja -v -j{} -C bin".format(tools.cpu_count()), run_environment=True)
+        if not cross_building(self):
+            rel_bindir = unix_path(self, os.path.relpath(os.path.join(self.cpp.build.bindir), os.getcwd()))
+            gn_args = [
+                rel_bindir,
+                f'--args="target_os=\\"{self._target_os}\\" target_cpu=\\"{self._target_cpu}\\""',
+            ]
+            self.run("gn gen " + " ".join(gn_args))
+            self.run(f"ninja -v -j{os.cpu_count()} -C {rel_bindir}")
 
     def test(self):
-        if not tools.cross_building(self.settings):
-            self.run(os.path.join("bin", "test_package"), run_environment=True)
+        if can_run(self):
+            bin_path = os.path.join(self.cpp.build.bindir, "test_package")
+            self.run(bin_path, env="conanrun")

recipes/gn/all/test_package/test_package.cpp

@@ -3,7 +3,7 @@
 
 #include <iostream>
 
-int main(int argc, char* argv[]) {
+int main() {
     std::cout << get_test_shared_text() << "\n";
     std::cout << get_test_static_text() << "\n";
     return 0;