[Adjust Rule] SIM904 false positive

[navotarad]

Desired change

• Rule(s): SIM904
• Adjustment: It should not trigger for "create or update" logic when it comes to dictionaries

Explanation

The warning points at the wrong line in the code, and is unavoidable in some situations

Example 1

In this example the warning message is confusing as it is raised against the a = {'b': 'c'} line, which is what the rule recommends writing

def f(a=None):
    if a is None:
        a = {"b": "c"}
    else:
        a["b"] = "c"

scratch.py:3:9: SIM904 Initialize dictionary 'a' directly

The warning can be avoided by writing the logic as

def f(a=None):
    if a is None:
        a = {}
    a['b'] = 'c'

which could be argued is better but it does not solve the issue of the next example.

Example 2

Here the creation logic for the dictionary is distinct from the update logic, and it also triggers the warning

def f(a=None):
    if a is None:
        a = {"b": "x"}
    else:
        a["b"] = "c"

scratch.py:3:9: SIM904 Initialize dictionary 'a' directly

Again the code can be rewritten as

def f(a=None):
    if a is None:
        a = {}
        b = "x"
    else:
        b = "c"
    a["b"] = b

to avoid the warning, but I certainly don't think this is better