quiet: clarify implementation

Author: davidhewitt

setuptools_rust/_utils.py

@@ -4,6 +4,11 @@
 def format_called_process_error(e: subprocess.CalledProcessError) -> str:
     """Helper to convert a CalledProcessError to an error message.
 
+
+    >>> format_called_process_error(subprocess.CalledProcessError(
+    ...     777, ['ls', '-la'], None, None
+    ... ))
+    '`ls -la` failed with code 777'
     >>> format_called_process_error(subprocess.CalledProcessError(
     ...     1, ['cargo', 'foo bar'], 'message', None
     ... ))
@@ -14,7 +19,9 @@ def format_called_process_error(e: subprocess.CalledProcessError) -> str:
     '`cargo` failed with code -1\\n-- Output captured from stdout:\\nstdout\\n-- Output captured from stderr:\\nstderr'
     """
     command = " ".join(_quote_whitespace(arg) for arg in e.cmd)
-    message = f"""`{command}` failed with code {e.returncode}
+    message = f"`{command}` failed with code {e.returncode}"
+    if e.stdout is not None:
+        message += f"""
 -- Output captured from stdout:
 {e.stdout}"""
 

setuptools_rust/build.py

@@ -207,8 +207,13 @@ def build_extension(
 
         # Execute cargo
         try:
+            # If quiet, capture all output and only show it in the exception
+            # If not quiet, forward all cargo output to stderr
+            stdout = subprocess.PIPE if quiet else sys.stderr.fileno()
             stderr = subprocess.PIPE if quiet else None
-            output = subprocess.check_output(command, env=env, stderr=stderr, text=True)
+            subprocess.run(
+                command, env=env, stdout=stdout, stderr=stderr, text=True, check=True
+            )
         except subprocess.CalledProcessError as e:
             raise CompileError(format_called_process_error(e))
 
@@ -218,10 +223,6 @@ def build_extension(
                 "requires Rust to be installed and cargo to be on the PATH"
             )
 
-        if not quiet:
-            if output:
-                print(output, file=sys.stderr)
-
         # Find the shared library that cargo hopefully produced and copy
         # it into the build directory as if it were produced by build_ext.
 

setuptools_rust/extension.py

@@ -232,7 +232,7 @@ def install_script(self, module_name: str, exe_path: str) -> None:
                 f.write(_SCRIPT_TEMPLATE.format(executable=repr(executable)))
 
     def _metadata(self, *, quiet: bool) -> "_CargoMetadata":
-        """Returns cargo metedata for this extension package.
+        """Returns cargo metadata for this extension package.
 
         Cached - will only execute cargo on first invocation.
         """
@@ -249,6 +249,8 @@ def _metadata(self, *, quiet: bool) -> "_CargoMetadata":
                 metadata_command.extend(self.cargo_manifest_args)
 
             try:
+                # If quiet, capture stderr and only show it on exceptions
+                # If not quiet, let stderr be inherited
                 stderr = subprocess.PIPE if quiet else None
                 payload = subprocess.check_output(
                     metadata_command, stderr=stderr, encoding="latin-1"