Enable --pretty by default for better error messages

docs/source/command_line.rst

@@ -937,6 +937,7 @@ in error messages.
 
     Use visually nicer output in error messages: use soft word wrap,
     show source code snippets, and show error location markers.
+    This is enabled by default. Use ``--no-pretty`` to disable.
 
 .. option:: --no-color-output
 

mypy/main.py

@@ -524,16 +524,9 @@ def add_invertible_flag(
         if help is not argparse.SUPPRESS:
             help += f" (inverse: {inverse})"
 
-        arg = group.add_argument(
-            flag, action="store_false" if default else "store_true", dest=dest, help=help
-        )
+        arg = group.add_argument(flag, action="store_true", dest=dest, help=help)
         dest = arg.dest
-        group.add_argument(
-            inverse,
-            action="store_true" if default else "store_false",
-            dest=dest,
-            help=argparse.SUPPRESS,
-        )
+        group.add_argument(inverse, action="store_false", dest=dest, help=argparse.SUPPRESS)
         if strict_flag:
             assert dest is not None
             strict_flag_names.append(flag)
@@ -1007,7 +1000,7 @@ def add_invertible_flag(
     )
     add_invertible_flag(
         "--pretty",
-        default=False,
+        default=True,
         help="Use visually nicer output in error messages:"
         " Use soft word wrap, show source code snippets,"
         " and show error location markers",

mypy/options.py

@@ -365,7 +365,7 @@ def __init__(self) -> None:
         self.hide_error_codes = False
         self.show_error_code_links = False
         # Use soft word wrap and show trimmed source snippets with error location markers.
-        self.pretty = False
+        self.pretty = True
         self.dump_graph = False
         self.dump_deps = False
         self.logical_deps = False

mypy/stubtest.py

@@ -2286,6 +2286,7 @@ def test_stubs(args: _Arguments, use_builtins_fixtures: bool = False) -> int:
 
     options = Options()
     options.incremental = False
+    options.pretty = False
     options.custom_typeshed_dir = args.custom_typeshed_dir
     if options.custom_typeshed_dir:
         options.abs_custom_typeshed_dir = os.path.abspath(options.custom_typeshed_dir)

mypy/test/helpers.py

@@ -352,11 +352,14 @@ def parse_options(
             raise RuntimeError("Specifying targets via the flags pragma is not supported.")
         if "--show-error-codes" not in flag_list:
             options.hide_error_codes = True
+        if "--pretty" not in flag_list:
+            options.pretty = False
     else:
         flag_list = []
         options = Options()
         options.error_summary = False
         options.hide_error_codes = True
+        options.pretty = False
 
     # Allow custom python version to override testfile_pyversion.
     if all(flag.split("=")[0] != "--python-version" for flag in flag_list):

mypy/test/testcmdline.py

@@ -66,6 +66,8 @@ def test_python_cmdline(testcase: DataDrivenTestCase, step: int) -> None:
         args.append("--hide-error-codes")
     if "--disallow-empty-bodies" not in args:
         args.append("--allow-empty-bodies")
+    if "--pretty" not in args:
+        args.append("--no-pretty")
     # Type check the program.
     fixed = [python3_path, "-m", "mypy"]
     env = os.environ.copy()

mypy/test/testdaemon.py

@@ -79,6 +79,18 @@ def parse_script(input: list[str]) -> list[list[str]]:
 def run_cmd(input: str) -> tuple[int, str]:
     if input[1:].startswith("mypy run --") and "--show-error-codes" not in input:
         input += " --hide-error-codes"
+    if "--pretty" not in input:
+        if input.startswith("dmypy ") and " -- " in input:
+            # For dmypy commands, mypy flags come after --, so append at end
+            input += " --no-pretty"
+        elif input.startswith("mypy ") and " -- " in input:
+            # For mypy commands, options come before --, so insert before --
+            input = input.replace(" -- ", " --no-pretty -- ", 1)
+        elif input.startswith("dmypy run ") or input.startswith("dmypy start"):
+            # dmypy commands without -- need the separator added
+            input += " -- --no-pretty"
+        elif input.startswith("mypy "):
+            input += " --no-pretty"
     if input.startswith("dmypy "):
         input = sys.executable + " -m mypy." + input
     if input.startswith("mypy "):

mypy/test/testerrorstream.py

@@ -27,6 +27,7 @@ def test_error_stream(testcase: DataDrivenTestCase) -> None:
     options = Options()
     options.show_traceback = True
     options.hide_error_codes = True
+    options.pretty = False
 
     logged_messages: list[str] = []
 

mypy/test/testpep561.py

@@ -124,7 +124,7 @@ def test_pep561(testcase: DataDrivenTestCase) -> None:
                     f.write(f"{s}\n")
             cmd_line.append(program)
 
-        cmd_line.extend(["--no-error-summary", "--hide-error-codes"])
+        cmd_line.extend(["--no-error-summary", "--hide-error-codes", "--no-pretty"])
         if python_executable != sys.executable:
             cmd_line.append(f"--python-executable={python_executable}")
 

mypy/test/testpythoneval.py

@@ -52,6 +52,7 @@ def test_python_evaluation(testcase: DataDrivenTestCase, cache_dir: str) -> None
         "--no-error-summary",
         "--hide-error-codes",
         "--allow-empty-bodies",
+        "--no-pretty",
         "--test-env",  # Speeds up some checks
     ]
     interpreter = python3_path

mypyc/test/test_commandline.py

@@ -50,7 +50,7 @@ def run_case(self, testcase: DataDrivenTestCase) -> None:
         try:
             # Compile program
             cmd = subprocess.run(
-                [sys.executable, "-m", "mypyc", *args],
+                [sys.executable, "-m", "mypyc", "--no-pretty", *args],
                 stdout=subprocess.PIPE,
                 stderr=subprocess.STDOUT,
                 cwd="tmp",