proposal for source() buildenv discussion

conan/tools/env/__init__.py

@@ -1,3 +1,4 @@
 from conan.tools.env.environment import Environment
 from conan.tools.env.virtualbuildenv import VirtualBuildEnv
 from conan.tools.env.virtualrunenv import VirtualRunEnv
+from conan.tools.env.virtualbuildenv import buildenv

conan/tools/env/virtualbuildenv.py

@@ -1,8 +1,16 @@
+from contextlib import contextmanager
+
 from conan.internal import check_duplicated_generator
 from conan.tools.env import Environment
 from conan.tools.env.virtualrunenv import runenv_from_cpp_info
 
 
+@contextmanager
+def buildenv(conanfile):
+    with VirtualBuildEnv(conanfile).vars().apply():
+        yield
+
+
 class VirtualBuildEnv:
     """ Calculates the environment variables of the build time context and produces a conanbuildenv
         .bat or .sh script
@@ -12,21 +20,27 @@ def __init__(self, conanfile):
         self._conanfile = conanfile
         self._conanfile.virtualbuildenv = False
         self.basename = "conanbuildenv"
-        # TODO: Make this use the settings_build
-        self.configuration = conanfile.settings.get_safe("build_type")
-        if self.configuration:
-            self.configuration = self.configuration.lower()
-        self.arch = conanfile.settings.get_safe("arch")
-        if self.arch:
-            self.arch = self.arch.lower()
+        self.configuration = None
+        self.arch = None
 
     @property
     def _filename(self):
+        if not self.configuration:
+            # TODO: Make this use the settings_build
+            configuration = self._conanfile.settings.get_safe("build_type")
+            configuration = configuration.lower() if configuration else None
+        else:
+            configuration = self.configuration
+        if not self.arch:
+            arch = self._conanfile.settings.get_safe("arch")
+            arch = arch.lower() if arch else None
+        else:
+            arch = self.arch
         f = self.basename
-        if self.configuration:
-            f += "-" + self.configuration.replace(".", "_")
-        if self.arch:
-            f += "-" + self.arch.replace(".", "_")
+        if configuration:
+            f += "-" + configuration.replace(".", "_")
+        if arch:
+            f += "-" + arch.replace(".", "_")
         return f
 
     def environment(self):

conans/client/source.py

@@ -67,7 +67,6 @@ def config_source(export_source_folder, conanfile, hook_manager):
             # First of all get the exported scm sources (if auto) or clone (if fixed)
             # Now move the export-sources to the right location
             merge_directories(export_source_folder, conanfile.folders.base_source)
-
             run_source_method(conanfile, hook_manager)
 
 

conans/test/integration/build_requires/test_build_requires_source_method.py

@@ -0,0 +1,91 @@
+import textwrap
+
+from conans.test.utils.tools import TestClient
+
+
+def test_build_requires_source():
+    c = TestClient()
+    tool = textwrap.dedent(r"""
+        import os
+        from conan import ConanFile
+        from conan.tools.files import chdir, save
+
+        class Tool(ConanFile):
+            name = "tool"
+            version = "0.1"
+            def package(self):
+                with chdir(self, self.package_folder):
+                    echo = f"@echo off\necho MY-TOOL! {self.name}/{self.version}!!"
+                    save(self, "bin/mytool.bat", echo)
+                    save(self, "bin/mytool.sh", echo)
+                    os.chmod("bin/mytool.sh", 0o777)
+        """)
+    pkg = textwrap.dedent("""
+        from conan import ConanFile
+        from conan.tools.env import buildenv
+        import platform
+
+        class Pkg(ConanFile):
+            name = "pkg"
+            version = "0.1"
+            tool_requires = "tool/0.1"
+
+            def source(self):
+                cmd = "mytool.bat" if platform.system() == "Windows" else "mytool.sh"
+                with buildenv(self):
+                    self.run(cmd)
+        """)
+    c.save({"tool/conanfile.py": tool,
+            "pkg/conanfile.py": pkg})
+    c.run("create tool")
+    c.run("create pkg")
+    assert "MY-TOOL! tool/0.1" in c.out
+
+    c.run("install pkg")  # to generate conanbuild script first, so it is available
+    c.run("source pkg")
+    assert "MY-TOOL! tool/0.1" in c.out
+
+
+"""
+ALTERNATIVE 1: in recipe, explicit
+def source(self):
+    cmd = "mytool.bat" if platform.system() == "Windows" else "mytool.sh"
+    with VirtualBuildEnv(conanfile).vars().apply():
+        self.run(cmd)
+
+- Need to bypass ``settings`` restriction in ``source()``
+- we can make a nice helper ``with buildenv``
+"""
+
+"""
+ALTERNATIVE 2: in recipe, attribute
+inject_source_buildenv = True
+
+def source(self):
+    cmd = "mytool.bat" if platform.system() == "Windows" else "mytool.sh"
+    self.run(cmd)
+
+- No need to bypass ``settings`` restriction in ``source()``
+"""
+
+"""
+ALTERNATIVE 3: always, this should be the expected default behavior
+
+def source(self):
+    cmd = "mytool.bat" if platform.system() == "Windows" else "mytool.sh"
+    self.run(cmd)
+
+- No need to bypass ``settings`` restriction in ``source()``
+- We might want to do an opt-out, just in case?
+"""
+
+"""
+ALTERNATIVE 4: global, controlled by conf
+
+def source(self):
+    cmd = "mytool.bat" if platform.system() == "Windows" else "mytool.sh"
+    self.run(cmd)
+
+- No need to bypass ``settings`` restriction in ``source()``
+- [conf] core.source:inject_buildenv=True/False
+"""