fix: remove the fallback backend for editable build error (#3159)

news/3159.removal.md

@@ -0,0 +1 @@
+PDM no longer falls back to `setuptools-pep660` when the build backend doesn't support PEP 660.

src/pdm/builders/editable.py

@@ -1,47 +1,27 @@
 from __future__ import annotations
 
 import os
-from typing import Any, ClassVar
-
-from pyproject_hooks import HookMissing
 
 from pdm.builders.base import EnvBuilder, wrap_error
-from pdm.termui import logger
 
 
 class EditableBuilder(EnvBuilder):
     """Build egg-info in isolated env with managed Python."""
 
-    FALLBACK_BACKEND: ClassVar[dict[str, Any]] = {
-        "build-backend": "setuptools_pep660",
-        "requires": ["setuptools_pep660"],
-    }
-
     @wrap_error
     def prepare_metadata(self, out_dir: str) -> str:
         if self.isolated:
             self.install(self._requires, shared=True)
-        try:
-            if self.isolated:
-                requires = self._hook.get_requires_for_build_editable(self.config_settings)
-                self.install(requires)
-            filename = self._hook.prepare_metadata_for_build_editable(out_dir, self.config_settings)
-        except HookMissing:
-            self.init_build_system(self.FALLBACK_BACKEND)
-            return self.prepare_metadata(out_dir)
+            requires = self._hook.get_requires_for_build_editable(self.config_settings)
+            self.install(requires)
+        filename = self._hook.prepare_metadata_for_build_editable(out_dir, self.config_settings)
         return os.path.join(out_dir, filename)
 
     @wrap_error
     def build(self, out_dir: str, metadata_directory: str | None = None) -> str:
         if self.isolated:
             self.install(self._requires, shared=True)
-        try:
-            if self.isolated:
-                requires = self._hook.get_requires_for_build_editable(self.config_settings)
-                self.install(requires)
-            filename = self._hook.build_editable(out_dir, self.config_settings, metadata_directory)
-        except HookMissing:
-            logger.warning("The build backend doesn't support PEP 660, falling back to setuptools-pep660")
-            self.init_build_system(self.FALLBACK_BACKEND)
-            return self.build(out_dir, metadata_directory=metadata_directory)
+            requires = self._hook.get_requires_for_build_editable(self.config_settings)
+            self.install(requires)
+        filename = self._hook.build_editable(out_dir, self.config_settings, metadata_directory)
         return os.path.join(out_dir, filename)