[clang] [Clang] Prevent null pointer dereference in Sema::CodeCompleteQualifi… (PR #90490)

[via cfe-commits]

https://github.com/smanna12 created https://github.com/llvm/llvm-project/pull/90490

…edId()

The null pointer dereference issue seems happening with in the expression NNS->getAsType().

Although dyn_cast_or_null<TemplateTypeParmType>() correctly handles null pointers, it doesn’t prevent the subsequent dereferencing operation.

The fix ensures that NNS pointer is not null before calling the getAsType() method, thus preventing potential runtime errors caused by attempting to access a null pointer.

>From 0dc9d073224136deb0b1d6518c5876c53fd2574f Mon Sep 17 00:00:00 2001
From: "Manna, Soumi" <soumi.manna at intel.com>
Date: Mon, 29 Apr 2024 08:53:24 -0700
Subject: [PATCH] [Clang] Prevent null pointer dereference in
 Sema::CodeCompleteQualifiedId()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The null pointer dereference issue seems happening with in the expression NNS->getAsType().

Although dyn_cast_or_null<TemplateTypeParmType>() correctly handles null pointers, it doesn’t prevent the subsequent dereferencing operation.

The fix ensures that NNS pointer is not null before calling the getAsType() method, thus preventing potential runtime errors caused by attempting to access a null pointer.
---
 clang/lib/Sema/SemaCodeComplete.cpp | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index c335017f243eb2..3f0ab10646fe5d 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -6714,14 +6714,16 @@ void Sema::CodeCompleteQualifiedId(Scope *S, CXXScopeSpec &SS,
 
   // If the scope is a concept-constrained type parameter, infer nested
   // members based on the constraints.
-  if (const auto *TTPT =
-          dyn_cast_or_null<TemplateTypeParmType>(NNS->getAsType())) {
-    for (const auto &R : ConceptInfo(*TTPT, S).members()) {
-      if (R.Operator != ConceptInfo::Member::Colons)
-        continue;
-      Results.AddResult(CodeCompletionResult(
-          R.render(*this, CodeCompleter->getAllocator(),
-                   CodeCompleter->getCodeCompletionTUInfo())));
+  if (NNS) {
+    if (const auto *TTPT =
+            dyn_cast_or_null<TemplateTypeParmType>(NNS->getAsType())) {
+      for (const auto &R : ConceptInfo(*TTPT, S).members()) {
+        if (R.Operator != ConceptInfo::Member::Colons)
+          continue;
+        Results.AddResult(CodeCompletionResult(
+            R.render(*this, CodeCompleter->getAllocator(),
+                     CodeCompleter->getCodeCompletionTUInfo())));
+      }
     }
   }