NoQ added inline comments.
================
Comment at:
clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp:1123-1124
+ "abs", Summary(ArgTypes{IntTy}, RetType{IntTy}, EvalCallAsPure)
+ .Case({ArgumentCondition(0, WithinRange, SingleValue(0)),
+ ReturnValueCondition(WithinRange, SingleValue(0))})
+ .Case({ArgumentCondition(0, WithinRange, Range(1, IntMax)),
----------------
NoQ wrote:
> The three-way state split is unjustified here. Usage of `abs` is not a
> sufficient indication that the value may be 0, otherwise:
> ```lang=c++
> int foo(int x, int y) {
> int z = abs(y); // Assuming 'abs' has taken branch on which y == 0...
> return x / z; // ... we'll be forced to emit a division by zero warning
> here.
> }
> ```
>
> Generally, there are very few cases when state splits upon function calls are
> justified. The common cases are:
> - The function returns bool and finding that bool is the only reason to ever
> call this function. Eg., `isalpha()` and such.
> - The function can at any time completely unpredictably take any of the
> branches, in other words, taint is involved. Eg., `scanf()` can always fail
> simply because the user of the program wrote something special into stdin.
> returns bool
Or something that kinda resembles bool (eg., `isalpha()` returns a variety of
different ints in practice due to its static lookup table implementation
strategy but the user only cares about whether it's zero or non-zero).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D79432/new/
https://reviews.llvm.org/D79432
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