[analyzer] PR41269: Add a bit of C++ smart pointer modeling.

Implement cplusplus.SmartPtrModeling, a new checker that doesn't
emit any warnings but models methods of smart pointers more precisely.

For now the only thing it does is make `(bool) P` return false when `P`
is a freshly moved pointer. This addresses a false positive in the
use-after-move-checker.

Differential Revision: https://reviews.llvm.org/D60796

llvm-svn: 358944

1 files changed, 18 insertions, 0 deletions

diff --git a/clang/test/Analysis/smart-ptr.cpp b/clang/test/Analysis/smart-ptr.cpp
new file mode 100644
index 00000000000..3f1782480b4
--- /dev/null
+++ b/clang/test/Analysis/smart-ptr.cpp
@@ -0,0 +1,18 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection\
+// RUN:   -analyzer-checker cplusplus.Move,cplusplus.SmartPtr\
+// RUN:   -std=c++11 -verify %s
+
+#include "Inputs/system-header-simulator-cxx.h"
+
+void clang_analyzer_warnIfReached();
+
+void derefAfterMove(std::unique_ptr<int> P) {
+  std::unique_ptr<int> Q = std::move(P);
+  if (Q)
+    clang_analyzer_warnIfReached(); // expected-warning{{REACHABLE}}
+  *Q.get() = 1; // no-warning
+  if (P)
+    clang_analyzer_warnIfReached(); // no-warning
+  // TODO: Report a null dereference (instead).
+  *P.get() = 1; // expected-warning {{Method called on moved-from object 'P'}}
+}