Fix 2 assert regressions for graph compatibility

conan/internal/graph/graph_binaries.py

@@ -164,8 +164,9 @@ def _compatible_find_existing_binaries(self, node, compatibles, remotes, update)
             for package_id, compatible_package in compatibles.items():
                 node._package_id = package_id  # Modifying package id under the hood, FIXME
                 node.binary = None  # Invalidate it
-                self._compatible_process_node_cache(node)  # Doesn't check remotes
-                if node.binary == BINARY_CACHE:
+                cache_latest_prev = self._compatible_cache_latest_prev(node)  # not check remotes
+                if cache_latest_prev:
+                    self._binary_in_cache(node, cache_latest_prev)
                     self._compatible_found(conanfile, package_id, compatible_package)
                     return
             # If not found in the cache, then look first one in servers
@@ -185,9 +186,9 @@ def _compatible_find_existing_binaries(self, node, compatibles, remotes, update)
                                       f"{conanfile.info.dump_diff(compatible_package)}")
                 node._package_id = package_id  # Modifying package id under the hood, FIXME
                 node.binary = None  # Invalidate it
-                self._compatible_process_node_cache(node)  # Doesn't check remotes
-                if node.binary == BINARY_CACHE:
-                    self._evaluate_cache_update(node.pref, node, remotes, update)
+                cache_latest_prev = self._compatible_cache_latest_prev(node)  # Not check remotes
+                if cache_latest_prev:
+                    self._evaluate_cache_update(cache_latest_prev, node, remotes, update)
                 else:
                     self._evaluate_download(node, remotes, update)
                 if node.binary in (BINARY_CACHE, BINARY_UPDATE, BINARY_DOWNLOAD):
@@ -198,7 +199,7 @@ def _compatible_find_existing_binaries(self, node, compatibles, remotes, update)
         node.binary = original_binary
         node._package_id = original_package_id
 
-    def _compatible_process_node_cache(self, node):
+    def _compatible_cache_latest_prev(self, node):
         """ simplified checking of compatible_packages, that should be found existing, but
         will never be built, for example. They cannot be editable either at this point.
         """
@@ -220,14 +221,16 @@ def _compatible_process_node_cache(self, node):
             if not self._evaluate_clean_pkg_folder_dirty(node, package_layout):
                 break
 
-        if cache_latest_prev is not None:
-            # This binary already exists in the cache, maybe can be updated
-            assert cache_latest_prev.revision
-            assert node.binary is None
-            node.binary = BINARY_CACHE
-            node.binary_remote = None
-            node.prev = cache_latest_prev.revision
-            node.pref_timestamp = cache_latest_prev.timestamp
+        return cache_latest_prev
+
+    @staticmethod
+    def _binary_in_cache(node, cache_latest_prev):
+        assert cache_latest_prev.revision
+        assert node.binary is None
+        node.binary = BINARY_CACHE
+        node.binary_remote = None
+        node.prev = cache_latest_prev.revision
+        node.pref_timestamp = cache_latest_prev.timestamp
 
     def _compatible_find_build_binary(self, node, compatibles):
         original_binary = node.binary

test/integration/package_id/test_cache_compatibles.py

@@ -180,6 +180,15 @@ def compatibility(conanfile):
     c.assert_listed_binary({"dep/0.1": ("ce92fac7c26ace631e30875ddbb3a58a190eb601",
                                         "Download (default)")})
 
+    # Now what happens if we have it in cache already
+    c.run(f"install consumer {base_settings} -s compiler.cppstd=17 --update")
+    assert "dep/0.1: Checking 3 compatible configurations" in c.out
+    assert "dep/0.1: Main binary package '6179018ccb6b15e6443829bf3640e25f2718b931' missing" in c.out
+    assert "Found compatible package 'ce92fac7c26ace631e30875ddbb3a58a190eb601': " \
+           "compiler.cppstd=14" in c.out
+    c.assert_listed_binary({"dep/0.1": ("ce92fac7c26ace631e30875ddbb3a58a190eb601",
+                                        "Cache")})
+
 
 class TestDefaultCompat:
 
@@ -475,3 +484,14 @@ def test_remove_plugin_file(self):
         c.save({"conanfile.txt": ""})
         c.run("install .", assert_error=True)
         assert "ERROR: The 'compatibility.py' plugin file doesn't exist" in c.out
+
+
+def test_compatible_prev_from_cache():
+    tc = TestClient()
+    tc.save({"conanfile.py": GenConanfile("pkg", "0.1").with_settings("compiler")})
+    settings = ("-s os=Linux -s arch=x86_64 -s compiler=gcc -s compiler.version=8 "
+                "-s compiler.libcxx=libstdc++11")
+    tc.run(f"create . {settings} -s=compiler.cppstd=17")
+    tc.run(f"install --requires=pkg/0.1 {settings} -s=compiler.cppstd=14 -u")
+    tc.assert_listed_binary({"pkg/0.1": ("6179018ccb6b15e6443829bf3640e25f2718b931",
+                                         "Cache")})