From d33f199910fa02cf7072f3227913e670c98d03a9 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Endre=20F=C3=BCl=C3=B6p?= <endre.fulop@sigmatechnology.se>
Date: Sun, 22 May 2022 23:28:10 +0200
Subject: [PATCH] [clang-tidy] Extend cert-oop57-cpp to check non-zero memset
 values

Clang Tidy check cert-oop57-cpp now checks for arbitrary-valued
arguments in memset expressions containing non-trivially
default-constructible instances. Previously it only checked literal 0 values.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D126186
---
 .../cert/NonTrivialTypesLibcMemoryCallsCheck.cpp           |  5 ++---
 clang-tools-extra/docs/ReleaseNotes.rst                    |  3 +++
 .../test/clang-tidy/checkers/cert-oop57-cpp.cpp            | 14 ++++++++++++++
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/cert/NonTrivialTypesLibcMemoryCallsCheck.cpp b/clang-tools-extra/clang-tidy/cert/NonTrivialTypesLibcMemoryCallsCheck.cpp
index 8e6acea..5c8da5b 100644
--- a/clang-tools-extra/clang-tidy/cert/NonTrivialTypesLibcMemoryCallsCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cert/NonTrivialTypesLibcMemoryCallsCheck.cpp
@@ -80,7 +80,7 @@ void NonTrivialTypesLibcMemoryCallsCheck::registerMatchers(
   auto IsRecordSizeOf =
       expr(sizeOfExpr(hasArgumentOfType(equalsBoundNode("Record"))));
   auto ArgChecker = [&](Matcher<CXXRecordDecl> RecordConstraint,
-                        BindableMatcher<Stmt> SecondArg) {
+                        BindableMatcher<Stmt> SecondArg = expr()) {
     return allOf(argumentCountIs(3),
                  hasArgument(0, IsStructPointer(RecordConstraint, true)),
                  hasArgument(1, SecondArg), hasArgument(2, IsRecordSizeOf));
@@ -89,8 +89,7 @@ void NonTrivialTypesLibcMemoryCallsCheck::registerMatchers(
   Finder->addMatcher(
       callExpr(callee(namedDecl(hasAnyName(
                    utils::options::parseListPair(BuiltinMemSet, MemSetNames)))),
-               ArgChecker(unless(isTriviallyDefaultConstructible()),
-                          expr(integerLiteral(equals(0)))))
+               ArgChecker(unless(isTriviallyDefaultConstructible())))
           .bind("lazyConstruct"),
       this);
   Finder->addMatcher(
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 5196c53..e21bee6 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -156,6 +156,9 @@ Changes in existing checks
   <clang-tidy/checks/bugprone-sizeof-expression>` when `sizeof(...)` is
   compared against a `__int128_t`.
 
+- Made :doc:`cert-oop57-cpp <clang-tidy/checks/cert-oop57-cpp>` more sensitive
+  by checking for an arbitrary expression in the second argument of `memset`.
+
 - Improved :doc:`cppcoreguidelines-prefer-member-initializer
   <clang-tidy/checks/cppcoreguidelines-prefer-member-initializer>` check.
 
diff --git a/clang-tools-extra/test/clang-tidy/checkers/cert-oop57-cpp.cpp b/clang-tools-extra/test/clang-tidy/checkers/cert-oop57-cpp.cpp
index a5a3873..880c5c3 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/cert-oop57-cpp.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/cert-oop57-cpp.cpp
@@ -88,3 +88,17 @@ void baz(const NonTrivial &Other) {
   mymemcmp(&Data, &Other, sizeof(Data));
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: consider using comparison operators instead of calling 'mymemcmp'
 }
+
+void nonNullSetValue() {
+  NonTrivial Data;
+  // Check non-null-valued second argument.
+  std::memset(&Data, 1, sizeof(Data));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: calling 'memset' on a non-trivially default constructible class is undefined
+}
+
+void nonLiteralSetValue(char C) {
+  NonTrivial Data;
+  // Check non-literal second argument.
+  std::memset(&Data, C, sizeof(Data));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: calling 'memset' on a non-trivially default constructible class is undefined
+}
-- 
2.7.4