From 9fbd394884198e00ee9b1463c8dc7171b7b5ec78 Mon Sep 17 00:00:00 2001
From: Ronny Pfannschmidt <opensource@ronnypfannschmidt.de>
Date: Thu, 27 Apr 2023 07:24:35 +0200
Subject: [PATCH 1/2] chore: add debug to internal api entrypoint

---
 src/setuptools_scm/__init__.py | 33 ++++++++++++++++++---------------
 src/setuptools_scm/_log.py     |  6 ++++++
 2 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/src/setuptools_scm/__init__.py b/src/setuptools_scm/__init__.py
index b29273c4..96c83495 100644
--- a/src/setuptools_scm/__init__.py
+++ b/src/setuptools_scm/__init__.py
@@ -143,23 +143,26 @@ def get_version(
 
 
 def _get_version(config: Configuration) -> str | None:
-    parsed_version = _do_parse(config)
-    if parsed_version is None:
-        return None
-    version_string = _format_version(
-        parsed_version,
-        version_scheme=config.version_scheme,
-        local_scheme=config.local_scheme,
-    )
-    if config.write_to is not None:
-        dump_version(
-            root=config.root,
-            version=version_string,
-            write_to=config.write_to,
-            template=config.write_to_template,
+    from ._log import magic_debug
+
+    with magic_debug():
+        parsed_version = _do_parse(config)
+        if parsed_version is None:
+            return None
+        version_string = _format_version(
+            parsed_version,
+            version_scheme=config.version_scheme,
+            local_scheme=config.local_scheme,
         )
+        if config.write_to is not None:
+            dump_version(
+                root=config.root,
+                version=version_string,
+                write_to=config.write_to,
+                template=config.write_to_template,
+            )
 
-    return version_string
+        return version_string
 
 
 # Public API
diff --git a/src/setuptools_scm/_log.py b/src/setuptools_scm/_log.py
index 35c050d0..abbdd0c2 100644
--- a/src/setuptools_scm/_log.py
+++ b/src/setuptools_scm/_log.py
@@ -92,3 +92,9 @@ def enable_debug(handler: logging.Handler = _default_handler) -> Iterator[None]:
         handler.setLevel(old_handler_level)
         if handler is not _default_handler:
             log.removeHandler(handler)
+
+
+@contextlib.contextmanager
+def magic_debug() -> Iterator[None]:
+    with enable_debug():
+        yield

From 8af496d3f58fc20bc5e005e2e99d6eb2bc3d8d43 Mon Sep 17 00:00:00 2001
From: Ronny Pfannschmidt <opensource@ronnypfannschmidt.de>
Date: Thu, 27 Apr 2023 07:26:39 +0200
Subject: [PATCH 2/2] fix #838: handle incorrectly passed empty tag regex as
 default

---
 src/setuptools_scm/__init__.py | 11 ++++++++++-
 src/setuptools_scm/version.py  | 21 ++++++++++++++-------
 testing/test_basic_api.py      |  7 +++++++
 3 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/src/setuptools_scm/__init__.py b/src/setuptools_scm/__init__.py
index 96c83495..faea673b 100644
--- a/src/setuptools_scm/__init__.py
+++ b/src/setuptools_scm/__init__.py
@@ -6,6 +6,7 @@
 
 import os
 import re
+import warnings
 from typing import Any
 from typing import Pattern
 from typing import TYPE_CHECKING
@@ -133,7 +134,15 @@ def get_version(
     version_cls = _validate_version_cls(version_cls, normalize)
     del normalize
     if isinstance(tag_regex, str):
-        tag_regex = re.compile(tag_regex)
+        if tag_regex == "":
+            warnings.warn(
+                DeprecationWarning(
+                    "empty regex for tag regex is invalid, using default"
+                )
+            )
+            tag_regex = DEFAULT_TAG_REGEX
+        else:
+            tag_regex = re.compile(tag_regex)
     config = Configuration(**locals())
     maybe_version = _get_version(config)
 
diff --git a/src/setuptools_scm/version.py b/src/setuptools_scm/version.py
index 128533cd..8cf48e82 100644
--- a/src/setuptools_scm/version.py
+++ b/src/setuptools_scm/version.py
@@ -38,10 +38,8 @@
 def _parse_version_tag(
     tag: str | object, config: _config.Configuration
 ) -> dict[str, str] | None:
-    tagstring = tag if isinstance(tag, str) else str(tag)
-    match = config.tag_regex.match(tagstring)
+    match = config.tag_regex.match(str(tag))
 
-    result = None
     if match:
         key: str | int
         if len(match.groups()) == 1:
@@ -49,14 +47,23 @@ def _parse_version_tag(
         else:
             key = "version"
 
+        full = match.group(0)
+        log.debug("%r %r %s", tag, config.tag_regex, match)
+        log.debug(
+            "key %s data %s, %s, %r", key, match.groupdict(), match.groups(), full
+        )
         result = {
             "version": match.group(key),
-            "prefix": match.group(0)[: match.start(key)],
-            "suffix": match.group(0)[match.end(key) :],
+            "prefix": full[: match.start(key)],
+            "suffix": full[match.end(key) :],
         }
 
-    log.debug(f"tag '{tag}' parsed to {result}")
-    return result
+        log.debug("tag %r parsed to %r", tag, result)
+        return result
+    else:
+        log.debug("tag %r did not parse", tag)
+
+        return None
 
 
 def callable_or_entrypoint(group: str, callable_or_name: str | Any) -> Any:
diff --git a/testing/test_basic_api.py b/testing/test_basic_api.py
index f1b4c4f1..6fd39bde 100644
--- a/testing/test_basic_api.py
+++ b/testing/test_basic_api.py
@@ -121,6 +121,13 @@ def test_empty_pretend_version_named(
     assert res.stdout == "12.34"
 
 
+def test_get_version_blank_tag_regex() -> None:
+    with pytest.warns(
+        DeprecationWarning, match="empty regex for tag regex is invalid, using default"
+    ):
+        setuptools_scm.get_version(tag_regex="")
+
+
 @pytest.mark.parametrize(
     "version", ["1.0", "1.2.3.dev1+ge871260", "1.2.3.dev15+ge871260.d20180625", "2345"]
 )