[clang] [dataflow] CXXForRangeStmt should extend flow condition (PR #80989)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Paul Semel (paulsemel)

<details>
<summary>Changes</summary>

This is needed in order to correctly assume implicit iterator validity in the iterator checker.

---
Full diff: https://github.com/llvm/llvm-project/pull/80989.diff


1 Files Affected:

- (modified) clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp (+6-3) 


``````````diff
diff --git a/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp b/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
index 4c88c46142d64d..f02c65094113ec 100644
--- a/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
+++ b/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp
@@ -103,9 +103,12 @@ class TerminatorVisitor
     return {nullptr, false};
   }
 
-  TerminatorVisitorRetTy VisitCXXForRangeStmt(const CXXForRangeStmt *) {
-    // Don't do anything special for CXXForRangeStmt, because the condition
-    // (being implicitly generated) isn't visible from the loop body.
+  TerminatorVisitorRetTy VisitCXXForRangeStmt(const CXXForRangeStmt *S) {
+    // Even though the condition isn't visible from the loop body, analysis
+    // might depend on the implicit implicit statements implied by the loop.
+    auto *Cond = S->getCond();
+    if (Cond != nullptr)
+      return extendFlowCondition(*Cond);
     return {nullptr, false};
   }
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/80989