https://github.com/mxms0 created
https://github.com/llvm/llvm-project/pull/117370
Do not warn if the index is an enum and we an determine statically that it's
within bounds.
>From 8fed333cf4221dbf1826351da80164db5d209c21 Mon Sep 17 00:00:00 2001
From: mxms <m...@google.com>
Date: Fri, 22 Nov 2024 15:09:07 -0500
Subject: [PATCH] [Wunsafe-buffer-usage] Fix false positives in handling enums
Do not warn if the index is an enum and we an determine statically that
it's within bounds.
---
clang/lib/Analysis/UnsafeBufferUsage.cpp | 7 +++++++
.../SemaCXX/warn-unsafe-buffer-usage-array.cpp | 17 +++++++++++++++++
2 files changed, 24 insertions(+)
diff --git a/clang/lib/Analysis/UnsafeBufferUsage.cpp
b/clang/lib/Analysis/UnsafeBufferUsage.cpp
index 5f36ffa926b269..addb724e2e2c9a 100644
--- a/clang/lib/Analysis/UnsafeBufferUsage.cpp
+++ b/clang/lib/Analysis/UnsafeBufferUsage.cpp
@@ -463,6 +463,13 @@ AST_MATCHER(ArraySubscriptExpr, isSafeArraySubscript) {
return true;
}
+ // Array index wasn't an integer literal, let's see if it was an enum or
+ // something similar
+ const auto IntConst =
Node.getIdx()->getIntegerConstantExpr(Finder->getASTContext());
+ if (IntConst && *IntConst > 0 && *IntConst < size) {
+ return true;
+ }
+
return false;
}
diff --git a/clang/test/SemaCXX/warn-unsafe-buffer-usage-array.cpp
b/clang/test/SemaCXX/warn-unsafe-buffer-usage-array.cpp
index c6c93a27e4b969..a65ecdf39edfcc 100644
--- a/clang/test/SemaCXX/warn-unsafe-buffer-usage-array.cpp
+++ b/clang/test/SemaCXX/warn-unsafe-buffer-usage-array.cpp
@@ -39,6 +39,23 @@ void constant_idx_unsafe(unsigned idx) {
buffer[10] = 0; // expected-note{{used in buffer access here}}
}
+enum FooEnum {
+ A = 0,
+ B = 1,
+ C = 2,
+ D
+};
+
+void constant_enum_safe() {
+ int buffer[FooEnum::D] = { 0, 1, 2 };
+ buffer[C] = 0; // no-warning
+}
+
+void constant_enum_unsafe(FooEnum e) {
+ int buffer[FooEnum::D] = { 0, 1, 2 };
+ buffer[e] = 0; // expected-warning{{unsafe buffer access}}
+}
+
void constant_id_string(unsigned idx) {
char safe_char = "abc"[1]; // no-warning
safe_char = ""[0];
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