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

[Paul Semel via cfe-commits]

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

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

>From b227aa82732cdc087ead5df62077055042d22696 Mon Sep 17 00:00:00 2001
From: Paul Semel <semelpaul at gmail.com>
Date: Wed, 7 Feb 2024 13:06:40 +0000
Subject: [PATCH] [dataflow] CXXForRangeStmt should extend flow condition

This is needed in order to correctly assume implicit iterator validity
in the iterator checker.
---
 .../FlowSensitive/TypeErasedDataflowAnalysis.cpp         | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

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};
   }