Thankfully, the world is changing. You have languages where variables are immutable by default or can be declared so that would prevent issues as http://www.viva64.com/en/d/0108/
Maybe gcc should do better for static analysis of a program. Expressions like `a && a` or `a == 1 || a != 2` should be caught easily.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71345
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77430
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64767
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77444
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And fixes have also started coming in:
https://gcc.gnu.org/viewcvs?rev=239959&root=gcc&view=rev
Kudos for investigating and reporting the issues.
sometimes I may keep overlapping expressions in a statement to remind me of the triggers I'm looking for at this point - and would likely use some meaningful constant names for the 1 and 2
statements aren't just logic - they're often documentation too - especially on code you might not look at again for months
I used to have many arguments with a professor whose code I was working on - he would factor out everything in an expression - removing all the parentheses and rely on operator precedence - it was often impenetrable (for me) - so I'd unpack it, wrap parentheses everywhere, change single letter vars to meaningful ones etc. - he'd be in my office an hour later ranting
Yes, it needs a warning because it's kind of obvious that there is something amiss about this expression. Only the author could tell what was specifically wrong.
I would advocate for the maintenance of both expressions if the comparison is tricky
If this is a hot path that must absolutely be optimized then a comment explaining the conditions is needed
And of course, the != 2 question might change (either because of a bug or logic change) but the == 1 might still be valid, however, if you took the first one your change will break the code
If it were a blog describing a 0-day vulnerability in a given software, I wouldn't have assumed that it would have been reported.