[clang] [clang] explicitly check if ParentMap contains key (PR #121736)

[Sameer Sahasrabuddhe via cfe-commits]

https://github.com/ssahasra created https://github.com/llvm/llvm-project/pull/121736

The implementation of ParentMap assumes that the key is absent if it is mapped to nullptr. This breaks when trying to store a tuple as the value type. Remove this assumption by explicit uses of `contains()` and `erase()`.

>From 2cae10eb0b1e94729c26299af018216e729607de Mon Sep 17 00:00:00 2001
From: Sameer Sahasrabuddhe <sameer.sahasrabuddhe at amd.com>
Date: Thu, 2 Jan 2025 14:30:07 +0530
Subject: [PATCH] [clang] explicitly check if ParentMap contains key

The implementation of ParentMap assumes that the key is absent if it is mapped
to nullptr. This breaks when trying to store a tuple as the value type. Remove
this assumption by explicit uses of `contains()` and `erase()`.
---
 clang/lib/AST/ParentMap.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/clang/lib/AST/ParentMap.cpp b/clang/lib/AST/ParentMap.cpp
index fd749b02b758c9..ada7b19487a782 100644
--- a/clang/lib/AST/ParentMap.cpp
+++ b/clang/lib/AST/ParentMap.cpp
@@ -34,13 +34,13 @@ static void BuildParentMap(MapTy& M, Stmt* S,
   case Stmt::PseudoObjectExprClass: {
     PseudoObjectExpr *POE = cast<PseudoObjectExpr>(S);
 
-    if (OVMode == OV_Opaque && M[POE->getSyntacticForm()])
+    if (OVMode == OV_Opaque && M.contains(POE->getSyntacticForm()))
       break;
 
     // If we are rebuilding the map, clear out any existing state.
-    if (M[POE->getSyntacticForm()])
+    if (M.contains(POE->getSyntacticForm()))
       for (Stmt *SubStmt : S->children())
-        M[SubStmt] = nullptr;
+        M.erase(SubStmt);
 
     M[POE->getSyntacticForm()] = S;
     BuildParentMap(M, POE->getSyntacticForm(), OV_Transparent);
@@ -78,7 +78,7 @@ static void BuildParentMap(MapTy& M, Stmt* S,
     // The right thing to do is to give the OpaqueValueExpr its syntactic
     // parent, then not reassign that when traversing the semantic expressions.
     OpaqueValueExpr *OVE = cast<OpaqueValueExpr>(S);
-    if (OVMode == OV_Transparent || !M[OVE->getSourceExpr()]) {
+    if (OVMode == OV_Transparent || !M.contains(OVE->getSourceExpr())) {
       M[OVE->getSourceExpr()] = S;
       BuildParentMap(M, OVE->getSourceExpr(), OV_Transparent);
     }