[3.12] gh-109972: Enhance test_gdb (#110026) (#110351)

* gh-109972: Enhance test_gdb (#110026)

* Split test_pycfunction.py: add test_cfunction_full.py.
  Split the function into the following 6 functions. In verbose
  mode, these "pycfunction" tests now log each tested call.

  * test_pycfunction_noargs()
  * test_pycfunction_o()
  * test_pycfunction_varargs()
  * test_pycfunction_varargs_keywords()
  * test_pycfunction_fastcall()
  * test_pycfunction_fastcall_keywords()

* Move get_gdb_repr() to PrettyPrintTests.
* Replace DebuggerTests.get_sample_script() with SAMPLE_SCRIPT.
* Rename checkout_hook_path to CHECKOUT_HOOK_PATH.
* Rename gdb_version to GDB_VERSION_TEXT.
* Replace (gdb_major_version, gdb_minor_version) with GDB_VERSION.
* run_gdb() uses "backslashreplace" error handler instead of "replace".
* Add check_gdb() function to util.py.
* Enhance support.check_cflags_pgo(): check also for sysconfig
  PGO_PROF_USE_FLAG (if available) in compiler flags.
* Move some SkipTest checks to test_gdb/__init__.py.
* Elaborate why gdb cannot be tested on Windows: gdb doesn't support
  PDB debug symbol files.

(cherry picked from commit 757cbd4)

* gh-104736: Fix test_gdb tests on ppc64le with clang (#109360)

Fix test_gdb on Python built with LLVM clang 16 on Linux ppc64le (ex:
Fedora 38). Search patterns in gdb "bt" command output to detect
when gdb fails to retrieve the traceback. For example, skip a test if
"Backtrace stopped: frame did not save the PC" is found.

(cherry picked from commit 44d9a71)

* gh-110166: Fix gdb CFunctionFullTests on ppc64le clang build (#110331)

CFunctionFullTests now also runs "bt" command before "py-bt-full",
similar to CFunctionTests which also runs "bt" command before
"py-bt". So test_gdb can skip the test if patterns like "?? ()" are
found in the gdb output.

(cherry picked from commit 1de9406)

Lib/test/support/__init__.py

@@ -785,14 +785,17 @@ def check_cflags_pgo():
     # Check if Python was built with ./configure --enable-optimizations:
     # with Profile Guided Optimization (PGO).
     cflags_nodist = sysconfig.get_config_var('PY_CFLAGS_NODIST') or ''
-    pgo_options = (
+    pgo_options = [
         # GCC
         '-fprofile-use',
         # clang: -fprofile-instr-use=code.profclangd
         '-fprofile-instr-use',
         # ICC
         "-prof-use",
-    )
+    ]
+    PGO_PROF_USE_FLAG = sysconfig.get_config_var('PGO_PROF_USE_FLAG')
+    if PGO_PROF_USE_FLAG:
+        pgo_options.append(PGO_PROF_USE_FLAG)
     return any(option in cflags_nodist for option in pgo_options)
 
 

Lib/test/test_gdb/__init__.py

@@ -4,7 +4,27 @@
 # Lib/test/test_jit_gdb.py
 
 import os
-from test.support import load_package_tests
+import sysconfig
+import unittest
+from test import support
+
+
+MS_WINDOWS = (os.name == 'nt')
+if MS_WINDOWS:
+    # On Windows, Python is usually built by MSVC. Passing /p:DebugSymbols=true
+    # option to MSBuild produces PDB debug symbols, but gdb doesn't support PDB
+    # debug symbol files.
+    raise unittest.SkipTest("test_gdb doesn't work on Windows")
+
+if support.PGO:
+    raise unittest.SkipTest("test_gdb is not useful for PGO")
+
+if not sysconfig.is_python_build():
+    raise unittest.SkipTest("test_gdb only works on source builds at the moment.")
+
+if support.check_cflags_pgo():
+    raise unittest.SkipTest("test_gdb is not reliable on PGO builds")
+
 
 def load_tests(*args):
-    return load_package_tests(os.path.dirname(__file__), *args)
+    return support.load_package_tests(os.path.dirname(__file__), *args)

Lib/test/test_gdb/test_backtrace.py

@@ -3,7 +3,7 @@
 from test import support
 from test.support import python_is_optimized
 
-from .util import setup_module, DebuggerTests, CET_PROTECTION
+from .util import setup_module, DebuggerTests, CET_PROTECTION, SAMPLE_SCRIPT
 
 
 def setUpModule():
@@ -15,7 +15,7 @@ class PyBtTests(DebuggerTests):
                      "Python was compiled with optimizations")
     def test_bt(self):
         'Verify that the "py-bt" command works'
-        bt = self.get_stack_trace(script=self.get_sample_script(),
+        bt = self.get_stack_trace(script=SAMPLE_SCRIPT,
                                   cmds_after_breakpoint=['py-bt'])
         self.assertMultilineMatches(bt,
                                     r'''^.*
@@ -35,7 +35,7 @@ def test_bt(self):
                      "Python was compiled with optimizations")
     def test_bt_full(self):
         'Verify that the "py-bt-full" command works'
-        bt = self.get_stack_trace(script=self.get_sample_script(),
+        bt = self.get_stack_trace(script=SAMPLE_SCRIPT,
                                   cmds_after_breakpoint=['py-bt-full'])
         self.assertMultilineMatches(bt,
                                     r'''^.*

Lib/test/test_gdb/test_cfunction.py

@@ -1,8 +1,6 @@
-import re
 import textwrap
 import unittest
 from test import support
-from test.support import python_is_optimized
 
 from .util import setup_module, DebuggerTests
 
@@ -11,10 +9,22 @@ def setUpModule():
     setup_module()
 
 
-@unittest.skipIf(python_is_optimized(),
+@unittest.skipIf(support.python_is_optimized(),
                  "Python was compiled with optimizations")
 @support.requires_resource('cpu')
 class CFunctionTests(DebuggerTests):
+    def check(self, func_name, cmd):
+        # Verify with "py-bt":
+        gdb_output = self.get_stack_trace(
+            cmd,
+            breakpoint=func_name,
+            cmds_after_breakpoint=['bt', 'py-bt'],
+            # bpo-45207: Ignore 'Function "meth_varargs" not
+            # defined.' message in stderr.
+            ignore_stderr=True,
+        )
+        self.assertIn(f'<built-in method {func_name}', gdb_output)
+
     # Some older versions of gdb will fail with
     #  "Cannot find new threads: generic error"
     # unless we add LD_PRELOAD=PATH-TO-libpthread.so.1 as a workaround
@@ -24,60 +34,52 @@ class CFunctionTests(DebuggerTests):
     # This is because we are calling functions from an "external" module
     # (_testcapimodule) rather than compiled-in functions. It seems difficult
     # to suppress these. See also the comment in DebuggerTests.get_stack_trace
-    def test_pycfunction(self):
+    def check_pycfunction(self, func_name, args):
         'Verify that "py-bt" displays invocations of PyCFunction instances'
-        # bpo-46600: If the compiler inlines _null_to_none() in meth_varargs()
-        # (ex: clang -Og), _null_to_none() is the frame #1. Otherwise,
-        # meth_varargs() is the frame #1.
-        expected_frame = r'#(1|2)'
+
+        if support.verbose:
+            print()
+
         # Various optimizations multiply the code paths by which these are
         # called, so test a variety of calling conventions.
-        for func_name, args in (
-            ('meth_varargs', ''),
-            ('meth_varargs_keywords', ''),
-            ('meth_o', '[]'),
-            ('meth_noargs', ''),
-            ('meth_fastcall', ''),
-            ('meth_fastcall_keywords', ''),
+        for obj in (
+            '_testcapi',
+            '_testcapi.MethClass',
+            '_testcapi.MethClass()',
+            '_testcapi.MethStatic()',
+
+            # XXX: bound methods don't yet give nice tracebacks
+            # '_testcapi.MethInstance()',
         ):
-            for obj in (
-                '_testcapi',
-                '_testcapi.MethClass',
-                '_testcapi.MethClass()',
-                '_testcapi.MethStatic()',
-
-                # XXX: bound methods don't yet give nice tracebacks
-                # '_testcapi.MethInstance()',
-            ):
-                with self.subTest(f'{obj}.{func_name}'):
-                    cmd = textwrap.dedent(f'''
-                        import _testcapi
-                        def foo():
-                            {obj}.{func_name}({args})
-                        def bar():
-                            foo()
-                        bar()
-                    ''')
-                    # Verify with "py-bt":
-                    gdb_output = self.get_stack_trace(
-                        cmd,
-                        breakpoint=func_name,
-                        cmds_after_breakpoint=['bt', 'py-bt'],
-                        # bpo-45207: Ignore 'Function "meth_varargs" not
-                        # defined.' message in stderr.
-                        ignore_stderr=True,
-                    )
-                    self.assertIn(f'<built-in method {func_name}', gdb_output)
-
-                    # Verify with "py-bt-full":
-                    gdb_output = self.get_stack_trace(
-                        cmd,
-                        breakpoint=func_name,
-                        cmds_after_breakpoint=['py-bt-full'],
-                        # bpo-45207: Ignore 'Function "meth_varargs" not
-                        # defined.' message in stderr.
-                        ignore_stderr=True,
-                    )
-                    regex = expected_frame
-                    regex += re.escape(f' <built-in method {func_name}')
-                    self.assertRegex(gdb_output, regex)
+            with self.subTest(f'{obj}.{func_name}'):
+                call = f'{obj}.{func_name}({args})'
+                cmd = textwrap.dedent(f'''
+                    import _testcapi
+                    def foo():
+                        {call}
+                    def bar():
+                        foo()
+                    bar()
+                ''')
+                if support.verbose:
+                    print(f'  test call: {call}', flush=True)
+
+                self.check(func_name, cmd)
+
+    def test_pycfunction_noargs(self):
+        self.check_pycfunction('meth_noargs', '')
+
+    def test_pycfunction_o(self):
+        self.check_pycfunction('meth_o', '[]')
+
+    def test_pycfunction_varargs(self):
+        self.check_pycfunction('meth_varargs', '')
+
+    def test_pycfunction_varargs_keywords(self):
+        self.check_pycfunction('meth_varargs_keywords', '')
+
+    def test_pycfunction_fastcall(self):
+        self.check_pycfunction('meth_fastcall', '')
+
+    def test_pycfunction_fastcall_keywords(self):
+        self.check_pycfunction('meth_fastcall_keywords', '')

Lib/test/test_gdb/test_cfunction_full.py

@@ -0,0 +1,36 @@
+"""
+Similar to test_cfunction but test "py-bt-full" command.
+"""
+
+import re
+
+from .util import setup_module
+from .test_cfunction import CFunctionTests
+
+
+def setUpModule():
+    setup_module()
+
+
+class CFunctionFullTests(CFunctionTests):
+    def check(self, func_name, cmd):
+        # Verify with "py-bt-full":
+        gdb_output = self.get_stack_trace(
+            cmd,
+            breakpoint=func_name,
+            cmds_after_breakpoint=['bt', 'py-bt-full'],
+            # bpo-45207: Ignore 'Function "meth_varargs" not
+            # defined.' message in stderr.
+            ignore_stderr=True,
+        )
+
+        # bpo-46600: If the compiler inlines _null_to_none() in
+        # meth_varargs() (ex: clang -Og), _null_to_none() is the
+        # frame #1. Otherwise, meth_varargs() is the frame #1.
+        regex = r'#(1|2)'
+        regex += re.escape(f' <built-in method {func_name}')
+        self.assertRegex(gdb_output, regex)
+
+
+# Delete the test case, otherwise it's executed twice
+del CFunctionTests

Lib/test/test_gdb/test_misc.py

@@ -2,7 +2,7 @@
 import unittest
 from test.support import python_is_optimized
 
-from .util import run_gdb, setup_module, DebuggerTests
+from .util import run_gdb, setup_module, DebuggerTests, SAMPLE_SCRIPT
 
 
 def setUpModule():
@@ -32,7 +32,7 @@ def assertListing(self, expected, actual):
 
     def test_basic_command(self):
         'Verify that the "py-list" command works'
-        bt = self.get_stack_trace(script=self.get_sample_script(),
+        bt = self.get_stack_trace(script=SAMPLE_SCRIPT,
                                   cmds_after_breakpoint=['py-list'])
 
         self.assertListing('   5    \n'
@@ -47,7 +47,7 @@ def test_basic_command(self):
 
     def test_one_abs_arg(self):
         'Verify the "py-list" command with one absolute argument'
-        bt = self.get_stack_trace(script=self.get_sample_script(),
+        bt = self.get_stack_trace(script=SAMPLE_SCRIPT,
                                   cmds_after_breakpoint=['py-list 9'])
 
         self.assertListing('   9    def baz(*args):\n'
@@ -58,7 +58,7 @@ def test_one_abs_arg(self):
 
     def test_two_abs_args(self):
         'Verify the "py-list" command with two absolute arguments'
-        bt = self.get_stack_trace(script=self.get_sample_script(),
+        bt = self.get_stack_trace(script=SAMPLE_SCRIPT,
                                   cmds_after_breakpoint=['py-list 1,3'])
 
         self.assertListing('   1    # Sample script for use by test_gdb\n'
@@ -101,15 +101,15 @@ def test_pyup_command(self):
     @unittest.skipUnless(HAS_PYUP_PYDOWN, "test requires py-up/py-down commands")
     def test_down_at_bottom(self):
         'Verify handling of "py-down" at the bottom of the stack'
-        bt = self.get_stack_trace(script=self.get_sample_script(),
+        bt = self.get_stack_trace(script=SAMPLE_SCRIPT,
                                   cmds_after_breakpoint=['py-down'])
         self.assertEndsWith(bt,
                             'Unable to find a newer python frame\n')
 
     @unittest.skipUnless(HAS_PYUP_PYDOWN, "test requires py-up/py-down commands")
     def test_up_at_top(self):
         'Verify handling of "py-up" at the top of the stack'
-        bt = self.get_stack_trace(script=self.get_sample_script(),
+        bt = self.get_stack_trace(script=SAMPLE_SCRIPT,
                                   cmds_after_breakpoint=['py-up'] * 5)
         self.assertEndsWith(bt,
                             'Unable to find an older python frame\n')
@@ -150,15 +150,15 @@ def test_print_after_up(self):
     @unittest.skipIf(python_is_optimized(),
                      "Python was compiled with optimizations")
     def test_printing_global(self):
-        bt = self.get_stack_trace(script=self.get_sample_script(),
+        bt = self.get_stack_trace(script=SAMPLE_SCRIPT,
                                   cmds_after_breakpoint=['py-up', 'py-print __name__'])
         self.assertMultilineMatches(bt,
                                     r".*\nglobal '__name__' = '__main__'\n.*")
 
     @unittest.skipIf(python_is_optimized(),
                      "Python was compiled with optimizations")
     def test_printing_builtin(self):
-        bt = self.get_stack_trace(script=self.get_sample_script(),
+        bt = self.get_stack_trace(script=SAMPLE_SCRIPT,
                                   cmds_after_breakpoint=['py-up', 'py-print len'])
         self.assertMultilineMatches(bt,
                                     r".*\nbuiltin 'len' = <built-in method len of module object at remote 0x-?[0-9a-f]+>\n.*")
@@ -167,7 +167,7 @@ class PyLocalsTests(DebuggerTests):
     @unittest.skipIf(python_is_optimized(),
                      "Python was compiled with optimizations")
     def test_basic_command(self):
-        bt = self.get_stack_trace(script=self.get_sample_script(),
+        bt = self.get_stack_trace(script=SAMPLE_SCRIPT,
                                   cmds_after_breakpoint=['py-up', 'py-locals'])
         self.assertMultilineMatches(bt,
                                     r".*\nargs = \(1, 2, 3\)\n.*")
@@ -176,7 +176,7 @@ def test_basic_command(self):
     @unittest.skipIf(python_is_optimized(),
                      "Python was compiled with optimizations")
     def test_locals_after_up(self):
-        bt = self.get_stack_trace(script=self.get_sample_script(),
+        bt = self.get_stack_trace(script=SAMPLE_SCRIPT,
                                   cmds_after_breakpoint=['py-up', 'py-up', 'py-locals'])
         self.assertMultilineMatches(bt,
                                     r'''^.*