From a67fea45926fb4dd57054c160eb95360a220d03c Mon Sep 17 00:00:00 2001
From: Tzu-ping Chung <uranusjr@gmail.com>
Date: Mon, 18 Jan 2021 15:54:43 +0800
Subject: [PATCH] Include both sources in inconsistency error

---
 news/9186.feature.rst                         |  3 +++
 src/pip/_internal/exceptions.py               | 13 +++++++-----
 .../resolution/resolvelib/candidates.py       | 21 +++++++++++++------
 tests/functional/test_install.py              |  2 +-
 4 files changed, 27 insertions(+), 12 deletions(-)
 create mode 100644 news/9186.feature.rst

diff --git a/news/9186.feature.rst b/news/9186.feature.rst
new file mode 100644
index 00000000000..175b5a883ac
--- /dev/null
+++ b/news/9186.feature.rst
@@ -0,0 +1,3 @@
+New resolver: Error message shown when a wheel contains inconsistent metadata
+is made more helpful by including both values from the file name and internal
+metadata.
diff --git a/src/pip/_internal/exceptions.py b/src/pip/_internal/exceptions.py
index 43d083205a0..2720b95f524 100644
--- a/src/pip/_internal/exceptions.py
+++ b/src/pip/_internal/exceptions.py
@@ -123,17 +123,20 @@ class MetadataInconsistent(InstallationError):
     that do not match the information previously obtained from sdist filename
     or user-supplied ``#egg=`` value.
     """
-    def __init__(self, ireq, field, built):
-        # type: (InstallRequirement, str, Any) -> None
+    def __init__(self, ireq, field, f_val, m_val):
+        # type: (InstallRequirement, str, str, str) -> None
         self.ireq = ireq
         self.field = field
-        self.built = built
+        self.f_val = f_val
+        self.m_val = m_val
 
     def __str__(self):
         # type: () -> str
-        return "Requested {} has different {} in metadata: {!r}".format(
-            self.ireq, self.field, self.built,
+        template = (
+            "Requested {} has inconsistent {}: "
+            "filename has {!r}, but metadata has {!r}"
         )
+        return template.format(self.ireq, self.field, self.f_val, self.m_val)
 
 
 class InstallationSubprocessError(InstallationError):
diff --git a/src/pip/_internal/resolution/resolvelib/candidates.py b/src/pip/_internal/resolution/resolvelib/candidates.py
index 6725684a515..91662b326b7 100644
--- a/src/pip/_internal/resolution/resolvelib/candidates.py
+++ b/src/pip/_internal/resolution/resolvelib/candidates.py
@@ -204,12 +204,21 @@ def _prepare_distribution(self):
     def _check_metadata_consistency(self, dist):
         # type: (Distribution) -> None
         """Check for consistency of project name and version of dist."""
-        name = canonicalize_name(dist.project_name)
-        if self._name is not None and self._name != name:
-            raise MetadataInconsistent(self._ireq, "name", dist.project_name)
-        version = dist.parsed_version
-        if self._version is not None and self._version != version:
-            raise MetadataInconsistent(self._ireq, "version", dist.version)
+        canonical_name = canonicalize_name(dist.project_name)
+        if self._name is not None and self._name != canonical_name:
+            raise MetadataInconsistent(
+                self._ireq,
+                "name",
+                self._name,
+                dist.project_name,
+            )
+        if self._version is not None and self._version != dist.parsed_version:
+            raise MetadataInconsistent(
+                self._ireq,
+                "version",
+                str(self._version),
+                dist.version,
+            )
 
     def _prepare(self):
         # type: () -> Distribution
diff --git a/tests/functional/test_install.py b/tests/functional/test_install.py
index 9c36fef0ecb..1c0650c6f5f 100644
--- a/tests/functional/test_install.py
+++ b/tests/functional/test_install.py
@@ -1455,7 +1455,7 @@ def test_install_editable_with_wrong_egg_name(script, resolver_variant):
             "for project name pkga. Fix your #egg=pkgb "
             "fragments.") in result.stderr
     if resolver_variant == "2020-resolver":
-        assert "has different name in metadata" in result.stderr, str(result)
+        assert "has inconsistent" in result.stderr, str(result)
     else:
         assert "Successfully installed pkga" in str(result), str(result)