solve build_scripts context issue with lockfiles

conan/cli/commands/create.py

@@ -49,10 +49,11 @@ def create(conan_api, parser, *args):
                                              lockfile=lockfile,
                                              remotes=remotes)
 
+    # FIXME: Dirty: package type still raw, not processed yet
+    is_build = args.build_require or conanfile.package_type == "build-scripts"
     # The package_type is not fully processed at export
     is_python_require = conanfile.package_type == "python-require"
-    lockfile = conan_api.lockfile.update_lockfile_export(lockfile, conanfile, ref,
-                                                         args.build_require)
+    lockfile = conan_api.lockfile.update_lockfile_export(lockfile, conanfile, ref, is_build)
 
     print_profiles(profile_host, profile_build)
     if args.build is not None and args.build_test is None:
@@ -66,13 +67,8 @@ def create(conan_api, parser, *args):
                                                          remotes=remotes, update=args.update,
                                                          python_requires=[ref])
     else:
-        requires = [ref] if not args.build_require else None
-        tool_requires = [ref] if args.build_require else None
-        # FIXME: Dirty: package type still raw, not processed yet
-        # TODO: Why not for package_type = "application" like cmake to be used as build-require?
-        if conanfile.package_type == "build-scripts" and not args.build_require:
-            # swap them
-            requires, tool_requires = tool_requires, requires
+        requires = [ref] if not is_build else None
+        tool_requires = [ref] if is_build else None
         deps_graph = conan_api.graph.load_graph_requires(requires, tool_requires,
                                                          profile_host=profile_host,
                                                          profile_build=profile_build,

conans/test/integration/lockfile/test_lock_requires.py

@@ -628,3 +628,19 @@ def test_error_test_explicit():
                  "test_package/conanfile.py": test})
     client.run("lock create conanfile.py --lockfile-out=my.lock")
     client.run("create . --lockfile=my.lock")
+
+
+def test_lock_error_create():
+    # https://github.com/conan-io/conan/issues/15801
+    c = TestClient()
+    c.save({"conanfile.py": GenConanfile("pkg", "0.1").with_package_type("build-scripts")})
+    c.run("lock create . -u --lockfile-out=none.lock")
+    lock = json.loads(c.load("none.lock"))
+    assert lock["requires"] == []
+    assert lock["build_requires"] == []
+    c.run("create . --lockfile=none.lock --lockfile-out=none_updated.lock")
+    # It doesn't crash, it used to
+    lock = json.loads(c.load("none_updated.lock"))
+    assert lock["requires"] == []
+    assert len(lock["build_requires"]) == 1
+    assert "pkg/0.1#4e9dba5c3041ba4c87724486afdb7eb4" in lock["build_requires"][0]