Szelethus added inline comments.
================
Comment at: clang/lib/StaticAnalyzer/Core/ProgramState.cpp:327
+using ObjCForLctxPair =
+ std::pair<const ObjCForCollectionStmt *, const LocationContext *>;
+
----------------
martong wrote:
> Why it is not enough to simply have ObjCForCollectionStmt* as a key?
`Environment` is the data structure we use to bind **values** to **statements**
(which would ideally be expressions only). The problem is that a statement on
its own isn't enough to identify where we are in the analysis:
```lang=c++
void traverse(Graph &G) {
// SubG may need to be modeled in different stackframes, but has the same Stmt*
for (Graph &SubG : G->successors()) {
traverse(SubG);
}
}
```
`LocationContext` can be thought of as a stack function calls (or anything with
a distinct stack frame). Indeed, if two `(Stmt *, LocationContext *)` pairs are
equal, we're rebinding the same expression (another loop iteration, goto), if
only the statements are the same, we're not in the same function call (//stack
frame//).
Of course `ObjCForCollectionStmt` can not have a value, that is the whole point
of the patch, but we still need a `LocationContext` to correctly identify
precisely which loop we're talking about.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D86736/new/
https://reviews.llvm.org/D86736
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