Print tracebacks for errors other than UserError and StopError. (Gary Oberbrunner)

6 files changed, 94 insertions, 9 deletions

diff --git a/doc/man/scons.1 b/doc/man/scons.1
index d4f2103..c63a23a 100644
--- a/doc/man/scons.1
+++ b/doc/man/scons.1
@@ -562,6 +562,11 @@ Building myprog.o with action(s):
 .EE
 
 .TP
+--debug=stacktrace
+Prints an internal Python stack trace
+when encountering an otherwise unexplained error.
+
+.TP
 --debug=time
 Prints various time profiling information: the time spent
 executing each build command, the total build time, the total time spent
diff --git a/src/CHANGES.txt b/src/CHANGES.txt
index b035acb..1965c61 100644
--- a/src/CHANGES.txt
+++ b/src/CHANGES.txt
@@ -73,6 +73,9 @@ RELEASE 0.97 - XXX
   - Add a PRINT_CMD_LINE_FUNC construction variable to allow people
     to filter (or log) command-line output.
 
+  - Print an internal Python stack trace in response to an otherwise
+    unexplained error when --debug=stacktrace is specified.
+
   From Kevin Quick:
 
   - Fix the Builder name returned from ListBuilders and other instances
diff --git a/src/engine/SCons/Script/__init__.py b/src/engine/SCons/Script/__init__.py
index dfee767..160fae3 100644
--- a/src/engine/SCons/Script/__init__.py
+++ b/src/engine/SCons/Script/__init__.py
@@ -141,8 +141,12 @@ class BuildTask(SCons.Taskmaster.Task):
         # is to display the various types of Errors and Exceptions
         # appropriately.
         status = 2
-        t, e = self.exc_info()[:2]
-        tb = None
+        exc_info = self.exc_info()
+        try:
+            t, e, tb = exc_info
+        except ValueError:
+            t, e = exc_info
+            tb = None
         if t is None:
             # The Taskmaster didn't record an exception for this Task;
             # see if the sys module has one.
@@ -166,7 +170,7 @@ class BuildTask(SCons.Taskmaster.Task):
                 s = s + '  Stop.'
             sys.stderr.write("scons: *** %s\n" % s)
 
-            if tb:
+            if tb and print_stacktrace:
                 sys.stderr.write("scons: internal stack trace:\n")
                 traceback.print_tb(tb, file=sys.stderr)
 
@@ -240,6 +244,7 @@ print_dtree = 0
 print_explanations = 0
 print_includes = 0
 print_objects = 0
+print_stacktrace = 0
 print_time = 0
 print_tree = 0
 memory_stats = None
@@ -400,7 +405,8 @@ def _set_globals(options):
     global repositories, keep_going_on_error, ignore_errors
     global print_count, print_dtree
     global print_explanations, print_includes
-    global print_objects, print_time, print_tree
+    global print_objects, print_stacktrace
+    global print_time, print_tree
     global memory_outf, memory_stats
 
     if options.repository:
@@ -423,6 +429,8 @@ def _set_globals(options):
                 print_objects = 1
             elif options.debug == "presub":
                 SCons.Action.print_actions_presub = 1
+            elif options.debug == "stacktrace":
+                print_stacktrace = 1
             elif options.debug == "time":
                 print_time = 1
             elif options.debug == "tree":
@@ -520,7 +528,8 @@ class OptParser(OptionParser):
 
         debug_options = ["count", "dtree", "explain",
                          "includes", "memory", "objects",
-                         "pdb", "presub", "time", "tree"]
+                         "pdb", "presub", "stacktrace",
+                         "time", "tree"]
 
         def opt_debug(option, opt, value, parser, debug_options=debug_options):
             if value in debug_options:
diff --git a/src/engine/SCons/Taskmaster.py b/src/engine/SCons/Taskmaster.py
index dab5026..84eb08d 100644
--- a/src/engine/SCons/Taskmaster.py
+++ b/src/engine/SCons/Taskmaster.py
@@ -461,5 +461,10 @@ class Taskmaster:
         self.pending = []
 
     def exception_raise(self, exception):
-        exc_type, exc_value = exception[:2]
-        raise exc_type, exc_value
+        exc = exception[:]
+        try:
+            exc_type, exc_value, exc_traceback = exc
+        except ValueError:
+            exc_type, exc_value = exc
+            exc_traceback = None
+        raise exc_type, exc_value, exc_traceback
diff --git a/src/engine/SCons/TaskmasterTests.py b/src/engine/SCons/TaskmasterTests.py
index 8865e09..a908192 100644
--- a/src/engine/SCons/TaskmasterTests.py
+++ b/src/engine/SCons/TaskmasterTests.py
@@ -921,7 +921,25 @@ class TaskmasterTestCase(unittest.TestCase):
         else:
             assert 0, "did not catch expected exception"
 
-        t.exception_set(("exception 3", "XYZZY"))
+        try:
+            1/0
+        except:
+            tb = sys.exc_info()[2]
+        t.exception_set(("exception 3", "arg", tb))
+        try:
+            t.exception_raise()
+        except:
+            exc_type, exc_value, exc_tb = sys.exc_info()
+            assert exc_type == 'exception 3', exc_type
+            assert exc_value == "arg", exc_value
+            import traceback
+            x = traceback.extract_tb(tb)[-1]
+            y = traceback.extract_tb(exc_tb)[-1]
+            assert x == y, "x = %s, y = %s" % (x, y)
+        else:
+            assert 0, "did not catch expected exception"
+
+        t.exception_set(("exception 4", "XYZZY"))
         def fw_exc(exc):
             raise 'exception_forwarded', exc
         tm.exception_raise = fw_exc 
@@ -930,7 +948,7 @@ class TaskmasterTestCase(unittest.TestCase):
         except:
             exc_type, exc_value = sys.exc_info()[:2]
             assert exc_type == 'exception_forwarded', exc_type
-            assert exc_value[0] == "exception 3", exc_value[0]
+            assert exc_value[0] == "exception 4", exc_value[0]
             assert exc_value[1] == "XYZZY", exc_value[1]
         else:
             assert 0, "did not catch expected exception"
diff --git a/test/option--debug.py b/test/option--debug.py
index 64cc424..e3d9960 100644
--- a/test/option--debug.py
+++ b/test/option--debug.py
@@ -384,4 +384,49 @@ test.must_match('file16.out', "file16.in\n")
 test.must_match('file17.out', "file17.in\n")
 test.must_match('file18.out', "file18.in\n")
 
+############################
+# test --debug=stacktrace
+
+test.write('SConstruct', """\
+def kfile_scan(node, env, target):
+    raise "kfile_scan error"
+
+kscan = Scanner(name = 'kfile',
+                function = kfile_scan,
+                skeys = ['.k'])
+
+env = Environment()
+env.Append(SCANNERS = [kscan])
+
+env.Command('foo', 'foo.k', Copy('$TARGET', '$SOURCE'))
+""")
+
+test.write('foo.k', "foo.k\n")
+
+test.run(status = 2, stderr = "scons: *** kfile_scan error\n")
+
+test.run(arguments = "--debug=stacktrace",
+         status = 2,
+         stderr = None)
+
+stderr = test.stderr()
+
+lines = [
+    "scons: *** kfile_scan error",
+    "scons: internal stack trace:",
+    'raise "kfile_scan error"',
+]
+
+missing = []
+for line in lines:
+    if string.find(stderr, line) == -1:
+        missing.append(line)
+
+if missing:
+    print "STDERR is missing the following lines:"
+    print "\t" + string.join(lines, "\n\t")
+    print "STDERR ====="
+    print stderr
+    test.fail_test(1)
+
 test.pass_test()