Improve error/warning messages

3 files changed, 10 insertions, 7 deletions

diff --git a/setuptools/config/_apply_pyprojecttoml.py b/setuptools/config/_apply_pyprojecttoml.py
index 2a046a78..421368af 100644
--- a/setuptools/config/_apply_pyprojecttoml.py
+++ b/setuptools/config/_apply_pyprojecttoml.py
@@ -332,13 +332,16 @@ _PREVIOUSLY_DEFINED = {
 
 
 class _WouldIgnoreField(UserWarning):
-    """Inform users that ``pyproject.toml`` would overwrite previously defined metadata.
+    """Inform users that ``pyproject.toml`` would overwrite previously defined metadata:
     !!\n\n
     ##############################################
     # field would be ignored by `pyproject.toml` #
     ##############################################
 
-    `{field} = {value!r}` seems to be defined outside of `pyproject.toml`.
+    The following seems to be defined outside of `pyproject.toml`:
+
+    `{field} = {value!r}`
+
     According to the spec (see the link bellow), however, setuptools CANNOT
     consider this value unless {field!r} is listed as `dynamic`.
 
diff --git a/setuptools/config/pyprojecttoml.py b/setuptools/config/pyprojecttoml.py
index d4e1460c..a712a258 100644
--- a/setuptools/config/pyprojecttoml.py
+++ b/setuptools/config/pyprojecttoml.py
@@ -285,9 +285,9 @@ class _ConfigExpander:
         previous = _PREVIOUSLY_DEFINED[field](dist)
         if not previous and not self.ignore_option_errors:
             msg = (
-                f"No configuration found for dynamic {field!r}. "
-                "Some fields need to be specified via `tool.setuptools.dynamic` "
-                "others must be specified via the equivalent attribute in `setup.py`."
+                f"No configuration found for dynamic {field!r}.\n"
+                "Some dynamic fields need to be specified via `tool.setuptools.dynamic`"
+                "\nothers must be specified via the equivalent attribute in `setup.py`."
             )
             raise OptionError(msg)
 
@@ -400,7 +400,7 @@ class _ExperimentalProjectMetadata(UserWarning):
 
 
 class _InvalidFile(UserWarning):
-    """Inform users that the given `pyproject.toml` is experimental.
+    """Inform users that the given `pyproject.toml` is experimental:
     !!\n\n
     ############################
     # Invalid `pyproject.toml` #
diff --git a/setuptools/tests/config/test_apply_pyprojecttoml.py b/setuptools/tests/config/test_apply_pyprojecttoml.py
index 42ec0f71..c09ff3e6 100644
--- a/setuptools/tests/config/test_apply_pyprojecttoml.py
+++ b/setuptools/tests/config/test_apply_pyprojecttoml.py
@@ -228,7 +228,7 @@ class TestPresetField:
         """
         pyproject = self.pyproject(tmp_path, [])
         dist = makedist(tmp_path, **{attr: value})
-        msg = f"{field}.*seems to be defined outside of .pyproject.toml."
+        msg = re.compile(f"defined outside of `pyproject.toml`:.*{field}", re.S)
         with pytest.warns(_WouldIgnoreField, match=msg):
             dist = pyprojecttoml.apply_configuration(dist, pyproject)