Hi all,
I'm stumbling with an issue where the co_firstlineno behavior changed from
Python 3.9 to Python 3.10 and I was wondering if this was intentional or
not.
i.e.: Whenever a code is compiled in Python 3.10, the `code.co_firstlineno`
is now always 1, whereas previously it was equal to the first statement.
Also, does anyone know if there is any way to restore the old behavior in
Python 3.10? I tried setting the `module.lineno` but it didn't really make
any difference...
As an example, given the code below:
import dis
source = '''
print(1)
print(2)
'''
initial_module = compile(source, '<nofilename>', 'exec', PyCF_ONLY_AST, 1)
import sys
print(sys.version)
for i in range(2):
module = Module([initial_module.body[i]], [])
module_code = compile(module, '<no filename>', 'exec')
print(' --> First lineno:', module_code.co_firstlineno)
print(' --> Line starts :', list(lineno for offset, lineno in
dis.findlinestarts(module_code)))
print('---- dis ---')
dis.dis(module_code)
I have the following outputs for Pyhon 3.9/Python 3.10:
3.9.6 (default, Jul 30 2021, 11:42:22) [MSC v.1916 64 bit (AMD64)]
--> First lineno: 2
--> Line starts : [2]
---- dis ---
2 0 LOAD_NAME 0 (print)
2 LOAD_CONST 0 (1)
4 CALL_FUNCTION 1
6 POP_TOP
8 LOAD_CONST 1 (None)
10 RETURN_VALUE
--> First lineno: 4
--> Line starts : [4]
---- dis ---
4 0 LOAD_NAME 0 (print)
2 LOAD_CONST 0 (2)
4 CALL_FUNCTION 1
6 POP_TOP
8 LOAD_CONST 1 (None)
10 RETURN_VALUE
3.10.0 (tags/v3.10.0:b494f59, Oct 4 2021, 19:00:18) [MSC v.1929 64 bit (AMD64)]
--> First lineno: 1
--> Line starts : [2]
---- dis ---
2 0 LOAD_NAME 0 (print)
2 LOAD_CONST 0 (1)
4 CALL_FUNCTION 1
6 POP_TOP
8 LOAD_CONST 1 (None)
10 RETURN_VALUE
--> First lineno: 1
--> Line starts : [4]
---- dis ---
4 0 LOAD_NAME 0 (print)
2 LOAD_CONST 0 (2)
4 CALL_FUNCTION 1
6 POP_TOP
8 LOAD_CONST 1 (None)
10 RETURN_VALUE
Thanks,
Fabio
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