[libcxx-commits] [PATCH] D110334: [libcxx][pretty printers] Check GDB Python scripting support

[David Spickett via Phabricator via libcxx-commits]

DavidSpickett created this revision.
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I found this after upgrading from Ubuntu bionic (gdb 8.1.1) to
Focal (gdb 9.2). (where this test fails, but that's for a
different patch)

9.2 allows you to set breakpoint commands from
Python, which was added in 8.3.
(bintutils a913fffbdee21fdd50e8de0596358be425775678
"Allow breakpoint commands to be set from Python")

The reason this test never failed before was because it did so
silently. "source <python file>" doesn't fail even if that script
raises an Exception.

To fix this extend the gdb lit feature to check that:

- gdb exists
- has Python support
- allows you to set breakpoint commands


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D110334

Files:
  libcxx/test/libcxx/gdb/gdb_pretty_printer_test.py
  libcxx/test/libcxx/gdb/gdb_pretty_printer_test.sh.cpp
  libcxx/utils/libcxx/test/features.py


Index: libcxx/utils/libcxx/test/features.py
===================================================================
--- libcxx/utils/libcxx/test/features.py
+++ libcxx/utils/libcxx/test/features.py
@@ -10,6 +10,7 @@
 import re
 import shutil
 import sys
+from subprocess import check_output, CalledProcessError, DEVNULL
 
 _isClang      = lambda cfg: '__clang__' in compilerMacros(cfg) and '__apple_build_version__' not in compilerMacros(cfg)
 _isAppleClang = lambda cfg: '__apple_build_version__' in compilerMacros(cfg)
@@ -159,10 +160,34 @@
   Feature(name='buildhost=windows', when=lambda cfg: platform.system().lower().startswith('windows'))
 ]
 
-# Detect whether GDB is on the system, and if so add a substitution to access it.
+# Detect whether GDB is on the system, has Python scripting and supports
+# adding breakpoint commands. If so add a substitution to access it.
+def check_gdb(cfg):
+  gdb_path = shutil.which('gdb')
+  if gdb_path is None:
+    return False
+
+  # Check that we can set breakpoint commands, which was added in 8.3
+  test_src = """\
+try:
+  gdb.Breakpoint(\"main\").commands=\"foo\"
+except AttributeError:
+  gdb.execute(\"quit 1\")
+gdb.execute(\"quit\")"""
+
+  try:
+    stdout = check_output([gdb_path, "-ex", "python " + test_src, "--batch"],
+                          stderr=DEVNULL, universal_newlines=True)
+  except CalledProcessError:
+    # We can't set breakpoint commands
+    return False
+
+  # Check we actually ran the Python
+  return not "Python scripting is not supported" in stdout
+
 DEFAULT_FEATURES += [
-  Feature(name='host-has-gdb',
-    when=lambda cfg: shutil.which('gdb') is not None,
+  Feature(name='host-has-gdb-with-python',
+    when=check_gdb,
     actions=[AddSubstitution('%{gdb}', lambda cfg: shutil.which('gdb'))]
   )
 ]
Index: libcxx/test/libcxx/gdb/gdb_pretty_printer_test.sh.cpp
===================================================================
--- libcxx/test/libcxx/gdb/gdb_pretty_printer_test.sh.cpp
+++ libcxx/test/libcxx/gdb/gdb_pretty_printer_test.sh.cpp
@@ -7,7 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-// REQUIRES: host-has-gdb
+// REQUIRES: host-has-gdb-with-python
 // UNSUPPORTED: libcpp-has-no-localization
 // UNSUPPORTED: c++03
 
Index: libcxx/test/libcxx/gdb/gdb_pretty_printer_test.py
===================================================================
--- libcxx/test/libcxx/gdb/gdb_pretty_printer_test.py
+++ libcxx/test/libcxx/gdb/gdb_pretty_printer_test.py
@@ -105,6 +105,7 @@
 test_bp.enabled = True
 test_bp.silent = True
 test_bp.commands = "print_and_compare\ncontinue"
+
 # "run" won't return if the program exits; ensure the script regains control.
 gdb.events.exited.connect(exit_handler)
 gdb.execute("run")


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