[clang] 4699789 - [clang][analyzer][NFC] Supplement comments in `evalFtell` of StreamChecker (#74291)

[via cfe-commits]

Author: Ben Shi
Date: 2023-12-06T10:26:30+08:00
New Revision: 4699789249e6945c46cdbecd1fee493cbe553c66

URL: https://github.com/llvm/llvm-project/commit/4699789249e6945c46cdbecd1fee493cbe553c66
DIFF: https://github.com/llvm/llvm-project/commit/4699789249e6945c46cdbecd1fee493cbe553c66.diff

LOG: [clang][analyzer][NFC] Supplement comments in `evalFtell` of StreamChecker (#74291)

Added: 
    

Modified: 
    clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp

Removed: 
    


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diff  --git a/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
index a4799b5f762ca..925fc90e35543 100644
--- a/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
@@ -1072,6 +1072,9 @@ void StreamChecker::evalFtell(const FnDescription *Desc, const CallEvent &Call,
   ProgramStateRef StateFailed = State->BindExpr(
       CE, C.getLocationContext(), SVB.makeIntVal(-1, C.getASTContext().LongTy));
 
+  // This function does not affect the stream state.
+  // Still we add success and failure state with the appropriate return value.
+  // StdLibraryFunctionsChecker can change these states (set the 'errno' state).
   C.addTransition(StateNotFailed);
   C.addTransition(StateFailed);
 }