python · isidentical · Aug 13, 2019 · Aug 13, 2019 · Aug 13, 2019 · Aug 13, 2019
diff --git a/Include/compile.h b/Include/compile.h
@@ -97,4 +97,9 @@ PyAPI_FUNC(int) _PyAST_Optimize(struct _mod *, PyArena *arena, int optimize);
 #define Py_eval_input 258
 #define Py_func_type_input 345
 
+/* Compiler Return Flags */
+#define CR_FALSE 0
+#define CR_TRUE 1
+#define CR_IGNORE 2 /* ignore do_not_return */
+
 #endif /* !Py_COMPILE_H */
diff --git a/Lib/test/test_dis.py b/Lib/test/test_dis.py
@@ -977,7 +977,7 @@ def jumpy():
   Instruction(opname='LOAD_CONST', opcode=100, arg=6, argval='Who let lolcatz into this test suite?', argrepr="'Who let lolcatz into this test suite?'", offset=96, starts_line=None, is_jump_target=False),
   Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=98, starts_line=None, is_jump_target=False),
   Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=100, starts_line=None, is_jump_target=False),
-  Instruction(opname='SETUP_FINALLY', opcode=122, arg=70, argval=174, argrepr='to 174', offset=102, starts_line=20, is_jump_target=True),
+  Instruction(opname='SETUP_FINALLY', opcode=122, arg=70, argval=174, argrepr='to 174', offset=102, starts_line=28, is_jump_target=True),
   Instruction(opname='SETUP_FINALLY', opcode=122, arg=12, argval=118, argrepr='to 118', offset=104, starts_line=None, is_jump_target=False),
   Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=1, argrepr='1', offset=106, starts_line=21, is_jump_target=False),
   Instruction(opname='LOAD_CONST', opcode=100, arg=7, argval=0, argrepr='0', offset=108, starts_line=None, is_jump_target=False),

diff --git a/Lib/test/test_grammar.py b/Lib/test/test_grammar.py
@@ -916,6 +916,16 @@ def test_break_in_finally(self):
                 break
         self.assertEqual(count, 0)
 
+        def g1():
+            for count in [0, 1]:
+                for count in [0, 1]:
+                    try:
+                        return count
+                    finally:
+                        break
+            return 3
+        self.assertEqual(g1(), 3)
+
     def test_continue_in_finally(self):
         count = 0
         while count < 2:
@@ -969,6 +979,15 @@ def test_continue_in_finally(self):
             break
         self.assertEqual(count, 1)
 
+        def g1():
+            for count in [0, 1]:
+                try:
+                    return count
+                finally:
+                    continue
+            return 3
+        self.assertEqual(g1(), 3)
+
     def test_return_in_finally(self):
         def g1():
             try:
@@ -991,6 +1010,17 @@ def g3():
                 return 4
         self.assertEqual(g3(), 4)
 
+        def g4():
+            for number in range(2):
+                try:
+                    return 1/number
+                finally:
+                    if number > 0:
+                        return number
+                    else:
+                        continue
+        self.assertEqual(g4(), 1)
+
     def test_yield(self):
         # Allowed as standalone statement
         def g(): yield 1

diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-08-13-09-41-55.bpo-37830.Zpn3R3.rst b/Misc/NEWS.d/next/Core and Builtins/2019-08-13-09-41-55.bpo-37830.Zpn3R3.rst
@@ -0,0 +1,3 @@
+Fix segfaults when continue/break inside of finally with a return inside of
+try. Also optimizes bytecode by cutting pieces that never going to be
+executed. (Contributed by Batuhan Taskaya)
diff --git a/Python/compile.c b/Python/compile.c
@@ -166,6 +166,8 @@ struct compiler {
                                     This can be used to temporarily visit
                                     nodes without emitting bytecode to
                                     check only errors. */
+    int c_do_not_return;         /* The compiler won't do anything except
+                                    syntax check when it sees a return */
 
     PyObject *c_const_cache;     /* Python dict holding all constants,
                                     including names tuple */
@@ -346,6 +348,7 @@ PyAST_CompileObject(mod_ty mod, PyObject *filename, PyCompilerFlags *flags,
     c.c_optimize = (optimize == -1) ? config->optimization_level : optimize;
     c.c_nestlevel = 0;
     c.c_do_not_emit_bytecode = 0;
+    c.c_do_not_return = CR_FALSE;
 
     if (!_PyAST_Optimize(mod, arena, c.c_optimize)) {
         goto finally;
@@ -2780,23 +2783,24 @@ compiler_return(struct compiler *c, stmt_ty s)
             return compiler_error(
                 c, "'return' with value in async generator");
     }
-    if (preserve_tos) {
-        VISIT(c, expr, s->v.Return.value);
-    }
-    for (int depth = c->u->u_nfblocks; depth--;) {
-        struct fblockinfo *info = &c->u->u_fblock[depth];
+    if (c->c_do_not_return != CR_TRUE){
+        if (preserve_tos) {
+            VISIT(c, expr, s->v.Return.value);
+        }
+        for (int depth = c->u->u_nfblocks; depth--;) {
+            struct fblockinfo *info = &c->u->u_fblock[depth];
 
-        if (!compiler_unwind_fblock(c, info, preserve_tos))
-            return 0;
-    }
-    if (s->v.Return.value == NULL) {
-        ADDOP_LOAD_CONST(c, Py_None);
-    }
-    else if (!preserve_tos) {
-        VISIT(c, expr, s->v.Return.value);
+            if (!compiler_unwind_fblock(c, info, preserve_tos))
+                return 0;
+        }
+        if (s->v.Return.value == NULL) {
+            ADDOP_LOAD_CONST(c, Py_None);
+        }
+        else if (!preserve_tos) {
+            VISIT(c, expr, s->v.Return.value);
+        }
+        ADDOP(c, RETURN_VALUE);
     }
-    ADDOP(c, RETURN_VALUE);
-
     return 1;
 }
 
@@ -2812,6 +2816,9 @@ compiler_break(struct compiler *c)
             ADDOP_JABS(c, JUMP_ABSOLUTE, info->fb_exit);
             return 1;
         }
+        if (info->fb_type == FINALLY_END && c->c_do_not_return == CR_FALSE){
+            c->c_do_not_return = CR_TRUE;
+        }
     }
     return compiler_error(c, "'break' outside loop");
 }
@@ -2826,6 +2833,9 @@ compiler_continue(struct compiler *c)
             ADDOP_JABS(c, JUMP_ABSOLUTE, info->fb_block);
             return 1;
         }
+        if (info->fb_type == FINALLY_END && c->c_do_not_return == CR_FALSE){
+            c->c_do_not_return = CR_TRUE;
+        }
         if (!compiler_unwind_fblock(c, info, 0))
             return 0;
     }
@@ -2876,6 +2886,13 @@ compiler_try_finally(struct compiler *c, stmt_ty s)
     if (body == NULL || end == NULL)
         return 0;
 
+    if (!compiler_push_fblock(c, FINALLY_END, body, end))
+        return 0;
+    c->c_do_not_emit_bytecode = 1;
+    VISIT_SEQ(c, stmt, s->v.Try.finalbody);
+    c->c_do_not_emit_bytecode = 0;
+    compiler_pop_fblock(c, FINALLY_END, body);
+
     /* `try` block */
     ADDOP_JREL(c, SETUP_FINALLY, end);
     compiler_use_next_block(c, body);
@@ -2894,10 +2911,12 @@ compiler_try_finally(struct compiler *c, stmt_ty s)
 
     /* `finally` block */
     compiler_use_next_block(c, end);
+    c->c_do_not_return = CR_IGNORE;
     if (!compiler_push_fblock(c, FINALLY_END, end, NULL))
         return 0;
     VISIT_SEQ(c, stmt, s->v.Try.finalbody);
     ADDOP(c, END_FINALLY);
+    c->c_do_not_return = CR_FALSE; /* be sure it is turned off */
     compiler_pop_fblock(c, FINALLY_END, end);
     return 1;
 }

diff --git a/Python/importlib.h b/Python/importlib.h
diff --git a/Python/importlib_zipimport.h b/Python/importlib_zipimport.h
@@ -723,7 +723,7 @@ const unsigned char _Py_M__zipimport[] = {
     0,0,0,114,9,0,0,0,114,9,0,0,0,114,10,0,
     0,0,218,20,95,103,101,116,95,100,101,99,111,109,112,114,
     101,115,115,95,102,117,110,99,254,1,0,0,115,24,0,0,
-    0,0,2,4,3,10,1,8,2,4,1,4,1,16,1,14,
+    0,0,2,4,3,10,1,8,2,4,7,4,251,16,1,14,
     1,10,1,18,2,6,2,10,1,114,144,0,0,0,99,2,
     0,0,0,0,0,0,0,0,0,0,0,17,0,0,0,9,
     0,0,0,67,0,0,0,115,128,1,0,0,124,1,92,8,