Fix UPCAddressofArraySubscriptGadget::getClaimedVarUseSites()

[juanvazquez]

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

[github-actions]

Thank you for submitting a Pull Request (PR) to the LLVM Project!

This PR will be automatically labeled and the relevant teams will be
notified.

If you wish to, you can add reviewers by using the "Reviewers" section on this page.

If this is not working for you, it is probably because you do not have write
permissions for the repository. In which case you can instead tag reviewers by
name in a comment by using @ followed by their GitHub username.

If you have received no comments on your PR for a week, you can request a review
by "ping"ing the PR by adding a comment “Ping”. The common courtesy "ping" rate
is once a week. Please remember that you are asking for valuable time from other developers.

If you have further questions, they may be answered by the LLVM GitHub User Guide.

You can also ask questions in a comment on this PR, on the LLVM Discord or on the forums.

[llvmbot]

@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-analysis

Author: juan.vazquez (juanvazquez)

Changes

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 --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}}
+}

[juanvazquez]

Fixes #88405

[jkorous-apple]

LGTM
Thank you for fixing this!

[juanvazquez]

Ping

A gentle ping in case there is something missing on my side to get this merged. It's my first time contributing to LLVM. Thanks!

[ldionne]

I just approved the CI runs. I think this can be merged once the CI is all green. Whoever sees this first with push access can merge.

[github-actions]

@juanvazquez Congratulations on having your first Pull Request (PR) merged into the LLVM Project!

Your changes will be combined with recent changes from other authors, then tested
by our build bots. If there is a problem with a build, you may receive a report in an email or a comment on this PR.

Please check whether problems have been caused by your change specifically, as
the builds can include changes from many authors. It is not uncommon for your
change to be included in a build that fails due to someone else's changes, or
infrastructure issues.

How to do this, and the rest of the post-merge process, is covered in detail here.

If your change does cause a problem, it may be reverted, or you can revert it yourself.
This is a normal part of LLVM development. You can fix your changes and open a new PR to merge them again.

If you don't get any reports, no action is required from you. Your changes are working as expected, well done!