From 9b1e4a8218b7fcb8900d0382704fdb4e38b52eb0 Mon Sep 17 00:00:00 2001
From: Artem Dergachev <artem.dergachev@gmail.com>
Date: Mon, 6 Apr 2020 20:27:40 +0300
Subject: [PATCH] [analyzer] Fix NSErrorChecker false positives on
 constructors.

Constructors and delete operators cannot return a boolean value.
Therefore they cannot possibly follow the NS/CFError-related coding
conventions.

Patch by Valeriy Savchenko!

Differential Revision: https://reviews.llvm.org/D77551
---
 .../lib/StaticAnalyzer/Checkers/NSErrorChecker.cpp | 11 +++++++++
 clang/test/Analysis/SpecialFunctionsCFError.cpp    | 28 ++++++++++++++++++++++
 2 files changed, 39 insertions(+)
 create mode 100644 clang/test/Analysis/SpecialFunctionsCFError.cpp

diff --git a/clang/lib/StaticAnalyzer/Checkers/NSErrorChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/NSErrorChecker.cpp
index 2dee1e4..5f68788 100644
--- a/clang/lib/StaticAnalyzer/Checkers/NSErrorChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/NSErrorChecker.cpp
@@ -95,6 +95,15 @@ public:
 };
 }
 
+static bool hasReservedReturnType(const FunctionDecl *D) {
+  if (isa<CXXConstructorDecl>(D))
+    return true;
+
+  // operators delete and delete[] are required to have 'void' return type
+  auto OperatorKind = D->getOverloadedOperator();
+  return OperatorKind == OO_Delete || OperatorKind == OO_Array_Delete;
+}
+
 void CFErrorFunctionChecker::checkASTDecl(const FunctionDecl *D,
                                         AnalysisManager &mgr,
                                         BugReporter &BR) const {
@@ -102,6 +111,8 @@ void CFErrorFunctionChecker::checkASTDecl(const FunctionDecl *D,
     return;
   if (!D->getReturnType()->isVoidType())
     return;
+  if (hasReservedReturnType(D))
+    return;
 
   if (!II)
     II = &D->getASTContext().Idents.get("CFErrorRef");
diff --git a/clang/test/Analysis/SpecialFunctionsCFError.cpp b/clang/test/Analysis/SpecialFunctionsCFError.cpp
new file mode 100644
index 0000000..3517933
--- /dev/null
+++ b/clang/test/Analysis/SpecialFunctionsCFError.cpp
@@ -0,0 +1,28 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=core,osx.coreFoundation.CFError \
+// RUN:   -verify %s
+
+typedef unsigned long size_t;
+struct __CFError {};
+typedef struct __CFError *CFErrorRef;
+void *malloc(size_t);
+
+class Foo {
+public:
+  Foo(CFErrorRef *error) {} // no-warning
+
+  void operator delete(void *pointer, CFErrorRef *error) { // no-warning
+    return;
+  }
+
+  void operator delete[](void *pointer, CFErrorRef *error) { // no-warning
+    return;
+  }
+
+  // Check that we report warnings for operators when it can be useful
+  void operator()(CFErrorRef *error) {} // expected-warning {{Function accepting CFErrorRef* should have a non-void return value to indicate whether or not an error occurred}}
+};
+
+// Check that global delete operator is not bothered as well
+void operator delete(void *pointer, CFErrorRef *error) { // no-warning
+  return;
+}
-- 
2.7.4