Add config variable 'general.error_on_override' (CONAN_ERROR_ON_OVERRIDE)

conans/client/conf/__init__.py

@@ -94,6 +94,7 @@
 # sysrequires_mode = enabled          # environment CONAN_SYSREQUIRES_MODE (allowed modes enabled/verify/disabled)
 # vs_installation_preference = Enterprise, Professional, Community, BuildTools # environment CONAN_VS_INSTALLATION_PREFERENCE
 # verbose_traceback = False           # environment CONAN_VERBOSE_TRACEBACK
+# error_on_override = False           # environment CONAN_ERROR_ON_OVERRIDE
 # bash_path = ""                      # environment CONAN_BASH_PATH (only windows)
 # recipe_linter = False               # environment CONAN_RECIPE_LINTER
 # read_only_cache = True              # environment CONAN_READ_ONLY_CACHE
@@ -184,6 +185,7 @@ def env_vars(self):
                "CONAN_USER_HOME_SHORT": self._env_c("general.user_home_short", "CONAN_USER_HOME_SHORT", None),
                "CONAN_USE_ALWAYS_SHORT_PATHS": self._env_c("general.use_always_short_paths", "CONAN_USE_ALWAYS_SHORT_PATHS", None),
                "CONAN_VERBOSE_TRACEBACK": self._env_c("general.verbose_traceback", "CONAN_VERBOSE_TRACEBACK", None),
+               "CONAN_ERROR_ON_OVERRIDE": self._env_c("general.error_on_override", "CONAN_ERROR_ON_OVERRIDE", "False"),
                # http://www.vtk.org/Wiki/CMake_Cross_Compiling
                "CONAN_CMAKE_GENERATOR": self._env_c("general.cmake_generator", "CONAN_CMAKE_GENERATOR", None),
                "CONAN_CMAKE_GENERATOR_PLATFORM": self._env_c("general.cmake_generator_platform", "CONAN_CMAKE_GENERATOR_PLATFORM", None),

conans/model/requires.py

@@ -4,6 +4,7 @@
 
 from conans.errors import ConanException
 from conans.model.ref import ConanFileReference
+from conans.util.env_reader import get_env
 
 
 class Requirement(object):
@@ -112,6 +113,8 @@ def update(self, down_reqs, output, own_ref, down_ref):
         assert isinstance(own_ref, ConanFileReference) if own_ref else True
         assert isinstance(down_ref, ConanFileReference) if down_ref else True
 
+        error_on_override = get_env("CONAN_ERROR_ON_OVERRIDE", False)
+
         new_reqs = down_reqs.copy()
         if own_ref:
             new_reqs.pop(own_ref.name, None)
@@ -123,9 +126,14 @@ def update(self, down_reqs, output, own_ref, down_ref):
                 # update dependency
                 other_ref = other_req.ref
                 if other_ref and other_ref != req.ref:
-                    output.info("%s requirement %s overridden by %s to %s "
-                                % (own_ref, req.ref, down_ref or "your conanfile",
-                                   other_ref))
+                    msg = "requirement %s overridden by %s to %s " \
+                          % (req.ref, down_ref or "your conanfile", other_ref)
+
+                    if error_on_override and not other_req.override:
+                        raise ConanException(msg)
+
+                    msg = "%s %s" % (own_ref, msg)
+                    output.warn(msg)
                     req.ref = other_ref
 
             new_reqs[name] = req

conans/test/functional/graph/conflict_diamond_test.py

@@ -1,38 +1,98 @@
+import os
+import textwrap
 import unittest
 
+from conans.client.tools import environment_append
 from conans.paths import CONANFILE
-from conans.test.utils.tools import TestClient
+from conans.test.utils.tools import TestClient, load
+import json
 
 
 class ConflictDiamondTest(unittest.TestCase):
+    conanfile = textwrap.dedent("""
+        from conans import ConanFile
 
-    def setUp(self):
-        self.client = TestClient()
+        class HelloReuseConan(ConanFile):
+            name = "%s"
+            version = "%s"
+            requires = %s
+        """)
 
     def _export(self, name, version, deps=None, export=True):
         deps = ", ".join(['"%s"' % d for d in deps or []]) or '""'
-        conanfile = """
-from conans import ConanFile, CMake
-import os
-
-class HelloReuseConan(ConanFile):
-    name = "%s"
-    version = "%s"
-    requires = %s
-""" % (name, version, deps)
+        conanfile = self.conanfile % (name, version, deps)
         files = {CONANFILE: conanfile}
         self.client.save(files, clean_first=True)
         if export:
             self.client.run("export . lasote/stable")
 
-    def reuse_test(self):
+    def setUp(self):
+        self.client = TestClient()
         self._export("Hello0", "0.1")
         self._export("Hello0", "0.2")
         self._export("Hello1", "0.1", ["Hello0/0.1@lasote/stable"])
         self._export("Hello2", "0.1", ["Hello0/0.2@lasote/stable"])
+
+    def test_conflict(self):
+        """ There is a conflict in the graph: branches with requirement in different
+            version, Conan will raise
+        """
         self._export("Hello3", "0.1", ["Hello1/0.1@lasote/stable", "Hello2/0.1@lasote/stable"],
                      export=False)
-
         self.client.run("install . --build missing", assert_error=True)
         self.assertIn("Conflict in Hello2/0.1@lasote/stable", self.client.user_io.out)
         self.assertNotIn("Generated conaninfo.txt", self.client.user_io.out)
+
+    def test_override_silent(self):
+        """ There is a conflict in the graph, but the consumer project depends on the conflicting
+            library, so all the graph will use the version from the consumer project
+        """
+        self._export("Hello3", "0.1",
+                     ["Hello1/0.1@lasote/stable", "Hello2/0.1@lasote/stable",
+                      "Hello0/0.1@lasote/stable"], export=False)
+        self.client.run("install . --build missing", assert_error=False)
+        self.assertIn("Hello2/0.1@lasote/stable requirement Hello0/0.2@lasote/stable overridden"
+                      " by Hello3/0.1@None/None to Hello0/0.1@lasote/stable",
+                      self.client.user_io.out)
+
+    def test_error_on_override(self):
+        """ Given a conflict in dependencies that is overridden by the consumer project, instead
+            of silently output a message, the user can force an error using
+            the env variable 'CONAN_ERROR_ON_OVERRIDE'
+        """
+        with environment_append({'CONAN_ERROR_ON_OVERRIDE': "True"}):
+            self._export("Hello3", "0.1",
+                         ["Hello1/0.1@lasote/stable", "Hello2/0.1@lasote/stable",
+                          "Hello0/0.1@lasote/stable"], export=False)
+            self.client.run("install . --build missing", assert_error=True)
+            self.assertIn("ERROR: Hello2/0.1@lasote/stable: requirement Hello0/0.2@lasote/stable"
+                          " overridden by Hello3/0.1@None/None to Hello0/0.1@lasote/stable",
+                          self.client.user_io.out)
+
+    def test_override_explicit(self):
+        """ Given a conflict in dependencies that is overridden by the consumer project (with
+            the explicit keyword 'override'), it won't raise because it is explicit, even if the
+            user has set env variable 'CONAN_ERROR_ON_OVERRIDE' to True
+        """
+        with environment_append({'CONAN_ERROR_ON_OVERRIDE': "True"}):
+            conanfile = self.conanfile % ("Hello3", "0.1",
+                                          '(("Hello1/0.1@lasote/stable"), '
+                                          '("Hello2/0.1@lasote/stable"), '
+                                          '("Hello0/0.1@lasote/stable", "override"),)')
+            self.client.save({CONANFILE: conanfile})
+            self.client.run("install . --build missing")
+            self.assertIn("Hello2/0.1@lasote/stable requirement Hello0/0.2@lasote/stable overridden"
+                          " by Hello3/0.1@None/None to Hello0/0.1@lasote/stable",
+                          self.client.user_io.out)
+
+            # ...but there is no way to tell Conan that 'Hello3' wants to depend also on 'Hello0'.
+            json_file = os.path.join(self.client.current_folder, 'tmp.json')
+            self.client.run('info . --only=requires --json="{}"'.format(json_file))
+            data = json.loads(load(json_file))
+            hello0 = data[0]
+            self.assertEqual(hello0["reference"], "Hello0/0.1@lasote/stable")
+            self.assertListEqual(sorted(hello0["required_by"]),
+                                 sorted(["Hello2/0.1@lasote/stable", "Hello1/0.1@lasote/stable"]))
+
+
+