[PATCH] D135247: [clang][analyzer] Add stream functions to StdLibraryFunctionsChecker.

[Balázs Kéri via Phabricator via cfe-commits]

balazske marked 3 inline comments as done.
balazske added a comment.

In D135247#3993351 <https://reviews.llvm.org/D135247#3993351>, @NoQ wrote:

> Also, similarly to `getenv()`, in these cases domain-specific knowledge may help suppress some unwanted reports. Eg., if a file has been opened successfully, this doesn't technically mean that it'll be open successfully again, but it makes it more likely, and the user does not necessarily care about time-of-check-time-of-use races. So maybe it'd make sense to eventually move some of that stuff to StreamChecker anyway. Maybe not, hard to tell, need to see the results.

This knowledge of "call history" can be implemented in an other checker, for the stream functions in `StreamChecker`, for `getenv` in a probably new checker (where the variable name could be stored). This `StdLibraryFunctionChecker` does not create the branch if the conditions (constraints) of a branch (summary case) are not satisfied. If another checker added branches in `evalCall` (for a success and failure case or only one of them) these are "selected" here only, not added.



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Comment at: clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp:1060-1064
+    } else if (NewState == State) {
+      if (const auto *D = dyn_cast_or_null<FunctionDecl>(Call.getDecl()))
+        if (const NoteTag *NT =
+                Case.getErrnoConstraint().describe(C, D->getNameAsString()))
+          C.addTransition(NewState, NT);
----------------
martong wrote:
> balazske wrote:
> > martong wrote:
> > > Why do we need this change?
> > It is possible that only the errno related state is changed, no new constraints are added (if the constraint is already here from `evalCall` but the errno was not set there, for example at `fclose` or other stream functions maybe no new state is created here). In such case the note tag is still needed.
> Okay, please add that as a comment to this new hunk.
The add of NoteTags could be improved. Probably a NoteTag should be displayed here if the return value (the "function call itself") is interesting. A text message should be specified for every function and the errno-related part added to it programatically if needed (if errno is interesting).


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https://reviews.llvm.org/D135247