have verbose logging imply printing stack traces

docs/notes/2.34.x.md

@@ -26,6 +26,8 @@ Published Pants binaries are now compiled with a new `dist` Cargo profile that e
 
 Pants option config files are now parsed as TOML 1.1 rather than TOML 1.0. This covers `pants.toml` and any other file named by `[GLOBAL].pants_config_files`, the rcfiles named by `[GLOBAL].pantsrc_files` (`/etc/pantsrc`, `~/.pants.rc` and `.pants.rc` by default), and `.toml` files referenced by `@fromfile` option values. Inline tables may now span multiple lines and end with a trailing comma, strings may use the `\e` and `\xHH` escapes, and times may omit their seconds. TOML 1.1 only adds syntax to TOML 1.0, so existing files continue to parse unchanged. TOML files read by backends, such as `pyproject.toml`, are unaffected.
 
+Full exception stack traces are now printed automatically when running at a verbose log level (`-ldebug` or `-ltrace`), unless `--no-print-stacktrace` is passed explicitly. In other words these logging levels imply `--print-stacktrace` by default.
+
 ### Goals
 
 ### Backends

src/python/pants/bin/local_pants_runner_integration_test.py

@@ -20,3 +20,11 @@ def run(args: Sequence[str]) -> PantsResult:
     assert "Traceback" in print_stacktrace.stderr
     assert "Engine traceback:" in print_stacktrace.stderr
     assert list_rule_name in print_stacktrace.stderr
+
+    debug = run(["-ldebug"])
+    assert "Traceback" in debug.stderr
+    assert "Engine traceback:" in debug.stderr
+    assert list_rule_name in debug.stderr
+
+    debug_no_stacktrace = run(["-ldebug", "--no-print-stacktrace"])
+    assert "Traceback" not in debug_no_stacktrace.stderr

src/python/pants/init/engine_initializer.py

@@ -228,7 +228,7 @@ def setup_graph(
             ca_certs_path=bootstrap_options.ca_certs_path,
             build_root=build_root,
             pants_workdir=bootstrap_options.pants_workdir,
-            include_trace_on_error=bootstrap_options.print_stacktrace,
+            include_trace_on_error=GlobalOptions.should_print_stacktrace(bootstrap_options),
             engine_visualize_to=bootstrap_options.engine_visualize_to,
             watch_filesystem=bootstrap_options.watch_filesystem,
             is_bootstrap=is_bootstrap,

src/python/pants/init/logging.py

@@ -16,6 +16,7 @@
 
 import pants.util.logging as pants_logging
 from pants.engine.internals import native_engine
+from pants.option.global_options import GlobalOptions
 from pants.option.option_value_container import OptionValueContainer
 from pants.util.dirutil import safe_mkdir_for
 from pants.util.docutil import doc_url
@@ -176,7 +177,7 @@ def initialize_stdio(global_bootstrap_options: OptionValueContainer) -> Iterator
         global_bootstrap_options.log_show_rust_3rdparty,
         global_bootstrap_options.show_log_target,
         _get_log_levels_by_target(global_bootstrap_options),
-        global_bootstrap_options.print_stacktrace,
+        GlobalOptions.should_print_stacktrace(global_bootstrap_options),
         global_bootstrap_options.ignore_warnings,
         global_bootstrap_options.pants_workdir,
     ):

src/python/pants/option/global_options.py

@@ -368,6 +368,17 @@ def compute_pantsd_invalidation_globs(
         )
         return tuple(invalidation_globs)
 
+    @staticmethod
+    def should_print_stacktrace(bootstrap_options: OptionValueContainer) -> bool:
+        """Whether full stack traces should be shown for errors.
+
+        An explicit `--[no-]print-stacktrace` always wins. Otherwise, stack traces are shown
+        implicitly at verbose log levels (`-ldebug` / `-ltrace`).
+        """
+        if not bootstrap_options.is_default("print_stacktrace"):
+            return bootstrap_options.print_stacktrace
+        return bootstrap_options.level in (LogLevel.DEBUG, LogLevel.TRACE)
+
     @memoized_classmethod
     def get_options_flags(cls) -> GlobalOptionsFlags:
         return GlobalOptionsFlags.create(cast("Type[GlobalOptions]", cls))

src/python/pants/option/global_options_test.py

@@ -15,10 +15,13 @@
 from pants.option.bootstrap_options import DynamicRemoteOptions, ExecutionOptions, RemoteProvider
 from pants.option.errors import OptionsError
 from pants.option.global_options import GlobalOptions
+from pants.option.option_value_container import OptionValueContainerBuilder
 from pants.option.options_bootstrapper import OptionsBootstrapper
+from pants.option.ranked_value import Rank, RankedValue
 from pants.testutil.option_util import create_dynamic_remote_options
 from pants.testutil.pytest_util import no_exception
 from pants.util.dirutil import safe_mkdir_for
+from pants.util.logging import LogLevel
 from pants.version import VERSION
 
 
@@ -144,6 +147,29 @@ def test_invalidation_globs() -> None:
         assert suffix not in glob
 
 
+@pytest.mark.parametrize(
+    "print_stacktrace, rank, level, expected",
+    [
+        (False, Rank.HARDCODED, LogLevel.INFO, False),
+        (False, Rank.HARDCODED, LogLevel.DEBUG, True),
+        (False, Rank.HARDCODED, LogLevel.TRACE, True),
+        (True, Rank.FLAG, LogLevel.INFO, True),
+        (True, Rank.FLAG, LogLevel.ERROR, True),
+        (False, Rank.FLAG, LogLevel.DEBUG, False),
+        (False, Rank.FLAG, LogLevel.TRACE, False),
+        (True, Rank.CONFIG, LogLevel.INFO, True),
+        (False, Rank.CONFIG, LogLevel.DEBUG, False),
+    ],
+)
+def test_should_print_stacktrace(
+    print_stacktrace: bool, rank: Rank, level: LogLevel, expected: bool
+) -> None:
+    builder = OptionValueContainerBuilder()
+    builder.print_stacktrace = RankedValue(rank, print_stacktrace)
+    builder.level = RankedValue(Rank.FLAG, level)
+    assert GlobalOptions.should_print_stacktrace(builder.build()) is expected
+
+
 @pytest.mark.parametrize(
     ("provider", "address", "expect_raises"),
     [