bpo-37500: Make sure dead code does not generate bytecode but also detect syntax errors (GH-14612)

https://bugs.python.org/issue37500

Add a new field to the compiler structure that allows to be configured
so no bytecode is emitted. In this way is possible to detect errors by
walking the nodes while preserving optimizations.


https://bugs.python.org/issue37500

1 files changed, 41 insertions, 7 deletions

diff --git a/Lib/test/test_sys_settrace.py b/Lib/test/test_sys_settrace.py
index 112ea87720..fdd789475d 100644
--- a/Lib/test/test_sys_settrace.py
+++ b/Lib/test/test_sys_settrace.py
@@ -53,22 +53,52 @@ basic.events = [(0, 'call'),
 # following that clause?
 
 
-# The entire "while 0:" statement is optimized away.  No code
-# exists for it, so the line numbers skip directly from "del x"
-# to "x = 1".
-def arigo_example():
+# Some constructs like "while 0:", "if 0:" or "if 1:...else:..." are optimized
+# away.  No code # exists for them, so the line numbers skip directly from
+# "del x" to "x = 1".
+def arigo_example0():
     x = 1
     del x
     while 0:
         pass
     x = 1
 
-arigo_example.events = [(0, 'call'),
+arigo_example0.events = [(0, 'call'),
                         (1, 'line'),
                         (2, 'line'),
                         (5, 'line'),
                         (5, 'return')]
 
+def arigo_example1():
+    x = 1
+    del x
+    if 0:
+        pass
+    x = 1
+
+arigo_example1.events = [(0, 'call'),
+                        (1, 'line'),
+                        (2, 'line'),
+                        (5, 'line'),
+                        (5, 'return')]
+
+def arigo_example2():
+    x = 1
+    del x
+    if 1:
+        x = 1
+    else:
+        pass
+    return None
+
+arigo_example2.events = [(0, 'call'),
+                        (1, 'line'),
+                        (2, 'line'),
+                        (4, 'line'),
+                        (7, 'line'),
+                        (7, 'return')]
+
+
 # check that lines consisting of just one instruction get traced:
 def one_instr_line():
     x = 1
@@ -349,8 +379,12 @@ class TraceTestCase(unittest.TestCase):
 
     def test_01_basic(self):
         self.run_test(basic)
-    def test_02_arigo(self):
-        self.run_test(arigo_example)
+    def test_02_arigo0(self):
+        self.run_test(arigo_example0)
+    def test_02_arigo1(self):
+        self.run_test(arigo_example1)
+    def test_02_arigo2(self):
+        self.run_test(arigo_example2)
     def test_03_one_instr(self):
         self.run_test(one_instr_line)
     def test_04_no_pop_blocks(self):