Szelethus added inline comments.
================
Comment at: clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp:107
+ /// This value applies to all error states in ErrorState except FEOF.
+ /// An EOF+indeterminate state is the same as EOF state.
+ bool FilePositionIndeterminate = false;
----------------
Szelethus wrote:
> What does this mean? "An EOF+indeterminate state is the same as EOF state." I
> don't understand the message you want to convey here -- is it that we cannot
> have an indeterminate file position indicator if we hit EOF, hence we regard
> a stream that is **known** to be EOF to have its file position indicator
> determinate?
>
> A good followup question for the uninitiated would be that "Well why is it
> ever legal to construct a `StreamState` object that can both have the
> `FilePositionIndeterminate` set to true and the `ErrorState` indicate that
> the steam is **known** to be in EOF?" Well, the answer is that we may only
> realize later that the error state can only be EOF, like in here:
> ```lang=c++
> void f() {
> FILE *F = fopen(...);
> if (fseek(F, ...)) {
> // Could be either EOF, ERROR, and ofc indeterminate
> if (eof(F)) {
> // This is where we have a seemingly impossible stream state, but its
> not a programming error, its a design decision.
> }
> }
> ```
> This might warrant a bit on explanation either here, or in
> `ensureNoFilePositionIndeterminate`. Probably the latter.
>
> With that said, can `SteamState`'s constructor ensure that we do not create a
> known to be EOF stream that is indeterminate?
Actually, not enforcing this could leave to false positives:
```
void f() {
FILE *F = fopen(...);
if (fseek(F, ...)) {
// Could be either EOF, ERROR, and ofc indeterminate
if (eof(F)) {
clearerr(F);
fseek(F, ...); // false positive warning
}
}
```
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D80018/new/
https://reviews.llvm.org/D80018
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