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In current FunctionMaker.create, if the function to create from is an async function and if the function body contains any occurrence of return, it will blindly replace it with return await. This will raise a SyntaxError in edge cases where return is present not as the keyword return but a substring.
Reproduce
from decorator import FunctionMaker
async def IDENTITY(return_value):
return return_value
FunctionMaker.create('WILL_RAISE_SYNTAX_ERROR()', 'return IDENTITY(return_value=actual_return_value)', dict(IDENTITY=IDENTITY, _call_=IDENTITY, actual_return_value=10), addsource=True)Error Message
Error in generated code:
async def WILL_RAISE_SYNTAX_ERROR():
return await IDENTITY(return await_value=actual_return await_value)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/opt/conda/lib/python3.9/site-packages/decorator.py", line 196, in create
return self.make(body, evaldict, addsource, **attrs)
File "/opt/conda/lib/python3.9/site-packages/decorator.py", line 159, in make
code = compile(src, filename, 'single')
File "<decorator-gen-0>", line 2
return await IDENTITY(return await_value=actual_return await_value)
^
SyntaxError: invalid syntax
Analysis
FunctionMaker.create has the following:
if caller and iscoroutinefunction(caller):
body = ('async def %(name)s(%(signature)s):\n' + ibody).replace(
'return', 'return await')However, this replacement is blind, if a parameter is named like return_value, it will be also replaced as it contains return (like the above example).
Moreover, the following lines can produce similar errors:
return_value = ...A simple assignment statement"This is a long message containing a return word"
Fix
To fix, we need to match return as a keyword rather than as any substring. A straightforward fix looks like the following (not fully tested):
if caller and iscoroutinefunction(caller):
rawbody = "async def %(name)s(%(signature)s):\n" + ibody
body = re.sub(r"(^|\s)return(\s)", r"\1return await\2", rawbody)Metadata
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