[clang] Fix UPCAddressofArraySubscriptGadget::getClaimedVarUseSites() (PR #88406)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-analysis

Author: juan.vazquez (juanvazquez)

<details>
<summary>Changes</summary>

UPCAddressofArraySubscriptGadget::getClaimedVarUseSites should skip parentheses when accessing the DeclRefExpr, otherwise a crash happens with parenthesized references.

---
Full diff: https://github.com/llvm/llvm-project/pull/88406.diff


2 Files Affected:

- (modified) clang/lib/Analysis/UnsafeBufferUsage.cpp (+1-1) 
- (added) clang/test/SemaCXX/warn-unsafe-buffer-usage-suggestions-crashes.cpp (+12) 


``````````diff
diff --git a/clang/lib/Analysis/UnsafeBufferUsage.cpp b/clang/lib/Analysis/UnsafeBufferUsage.cpp
index e03fe1b6830043..c42e70d5b95ac1 100644
--- a/clang/lib/Analysis/UnsafeBufferUsage.cpp
+++ b/clang/lib/Analysis/UnsafeBufferUsage.cpp
@@ -1114,7 +1114,7 @@ class UPCAddressofArraySubscriptGadget : public FixableGadget {
   virtual DeclUseList getClaimedVarUseSites() const override {
     const auto *ArraySubst = cast<ArraySubscriptExpr>(Node->getSubExpr());
     const auto *DRE =
-        cast<DeclRefExpr>(ArraySubst->getBase()->IgnoreImpCasts());
+        cast<DeclRefExpr>(ArraySubst->getBase()->IgnoreParenImpCasts());
     return {DRE};
   }
 };
diff --git a/clang/test/SemaCXX/warn-unsafe-buffer-usage-suggestions-crashes.cpp b/clang/test/SemaCXX/warn-unsafe-buffer-usage-suggestions-crashes.cpp
new file mode 100644
index 00000000000000..bf4faec184ee17
--- /dev/null
+++ b/clang/test/SemaCXX/warn-unsafe-buffer-usage-suggestions-crashes.cpp
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage \
+// RUN:            -fsafe-buffer-usage-suggestions \
+// RUN:            %s -verify %s
+
+char * unsafe_pointer; // expected-warning{{'unsafe_pointer' is an unsafe pointer used for buffer access}}
+
+void test(char * param) {
+}
+
+void dre_parenthesized() {
+  test(&(unsafe_pointer)[1]); // no-crash // expected-note{{used in buffer access here}}
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/88406