backport of <host_version> to 1.X

conans/client/graph/graph_builder.py

@@ -404,6 +404,18 @@ def _config_node(node, down_ref, down_options):
 
     def _resolve_recipe(self, current_node, dep_graph, requirement, check_updates,
                         update, remotes, profile, graph_lock, original_ref=None):
+
+        ref = requirement.ref
+        if ref.version == "<host_version>":
+            if not requirement.build_require:
+                raise ConanException(f"{current_node.ref} uses '<host_version>' in requires, "
+                                     "it is only allowed in tool_requires")
+            transitive = current_node._public_deps.get(ref.name, context="host")
+            if transitive is None:
+                raise ConanException(
+                    f"{current_node.ref} require '{ref}': didn't find a matching host dependency")
+            requirement.ref = transitive.ref
+
         try:
             result = self._proxy.get_recipe(requirement.ref, check_updates, update,
                                             remotes, self._recorder)

conans/model/ref.py

@@ -153,7 +153,7 @@ def validate_name(name, reference_token=None):
     @staticmethod
     def validate_version(version, pkg_name):
         ConanName.validate_string(version)
-        if version == "*":
+        if version == "*" or version == "<host_version>":
             return
         if ConanName._validation_pattern.match(version) is None:
             if (

conans/test/integration/build_requires/build_requires_test.py

@@ -1,7 +1,9 @@
+import json
 import os
 import textwrap
 import unittest
 
+import pytest
 from parameterized.parameterized import parameterized
 
 from conans.model.ref import ConanFileReference
@@ -527,3 +529,102 @@ class BuildReqConan(ConanFile):
     client.save({"conanfile.txt": consumer}, clean_first=True)
     client.run("install . --build=missing")
     assert "Applying build-requirement: build_req/1.0@test/test" in client.out
+
+
+class TestBuildTrackHost:
+
+    @pytest.mark.parametrize("build_profile", [False, True])
+    def test_overriden_host_version(self, build_profile):
+        """
+        Make the tool_requires follow the regular require with the expression "<host_version>"
+        """
+        c = TestClient()
+        pkg = textwrap.dedent("""
+            from conan import ConanFile
+            class ProtoBuf(ConanFile):
+                name = "pkg"
+                version = "0.1"
+                def requirements(self):
+                    self.requires("protobuf/1.0")
+                def build_requirements(self):
+                    self.tool_requires("protobuf/<host_version>")
+            """)
+        c.save({"protobuf/conanfile.py": GenConanfile("protobuf"),
+                "pkg/conanfile.py": pkg,
+                "app/conanfile.py": GenConanfile().with_requires("pkg/0.1")
+                                                  .with_requirement("protobuf/1.1", override=True)})
+        c.run("create protobuf 1.0@")
+        c.run("create protobuf 1.1@")
+        build_profile = "-pr:b default" if build_profile else ""
+        c.run(f"create pkg {build_profile}")
+        c.run(f"install pkg {build_profile}")  # make sure it doesn't crash
+        c.run(f"install app {build_profile}")
+        assert "protobuf/1.1" in c.out
+        assert "protobuf/1.0:" not in c.out
+
+        # verify locks work
+        c.run(f"lock create app/conanfile.py {build_profile}")
+        lock = c.load("conan.lock")
+        assert "protobuf/1.1" in lock
+        assert "protobuf/1.0" not in lock
+        # lock can be used
+        c.run(f"install app --lockfile=conan.lock")
+        assert "protobuf/1.1" in c.out
+        assert "protobuf/1.0:" not in c.out
+
+    @pytest.mark.parametrize("build_profile", [False, True])
+    def test_overriden_host_version_version_range(self, build_profile):
+        """
+        same as above, but using version ranges instead of overrides
+        """
+        build_profile = "-pr:b default" if build_profile else ""
+        c = TestClient()
+        c.save({"protobuf/conanfile.py": GenConanfile("protobuf"),
+                "pkg/conanfile.py": GenConanfile("pkg", "0.1").with_requirement("protobuf/[*]")
+               .with_build_requirement("protobuf/<host_version>"),
+                "app/conanfile.py": GenConanfile().with_requires("pkg/0.1")})
+        c.run("create protobuf 1.0@")
+        c.run(f"create pkg {build_profile}")
+        c.run(f"install pkg {build_profile}")  # make sure it doesn't crash
+        c.run(f"install app {build_profile}")
+        assert "protobuf/1.0" in c.out
+        assert "protobuf/1.1" not in c.out
+
+        c.run("create protobuf 1.1@")
+        c.run(f"install pkg {build_profile}")  # make sure it doesn't crash
+        c.run(f"install app {build_profile}")
+        assert "protobuf/1.1" in c.out
+        assert "protobuf/1.0" not in c.out
+
+        # verify locks work
+        c.run(f"lock create app/conanfile.py {build_profile}")
+        lock = c.load("conan.lock")
+        assert "protobuf/1.1" in lock
+        assert "protobuf/1.0" not in lock
+        # lock can be used
+        c.run("install app --lockfile=conan.lock")
+        assert "protobuf/1.1" in c.out
+        assert "protobuf/1.0:" not in c.out
+
+    @pytest.mark.parametrize("build_profile", [False, True])
+    def test_track_host_error_nothost(self, build_profile):
+        """
+        if no host requirement is defined, it will be an error
+        """
+        build_profile = "-pr:b default" if build_profile else ""
+        c = TestClient()
+        c.save({"conanfile.py":
+                GenConanfile("pkg").with_build_requirement("protobuf/<host_version>")})
+        c.run(f"install . {build_profile}", assert_error=True)
+        assert "'protobuf/<host_version>': didn't find a matching host dependency" in c.out
+
+    @pytest.mark.parametrize("build_profile", [False, True])
+    def test_track_host_error_wrong_context(self, build_profile):
+        """
+        it can only be used by tool_requires, not regular requires
+        """
+        build_profile = "-pr:b default" if build_profile else ""
+        c = TestClient()
+        c.save({"conanfile.py": GenConanfile("pkg").with_requirement("protobuf/<host_version>")})
+        c.run(f"install . {build_profile}", assert_error=True)
+        assert "uses '<host_version>' in requires" in c.out