[PATCH] D75678: [analyzer] Skip analysis of inherited ctor as top-level function

[Gabor Marton via Phabricator via cfe-commits]

martong created this revision.
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Skip analysis of inherited constructors as top-level functions because we
cannot model the parameters.

CXXInheritedCtorInitExpr doesn't take arguments and doesn't model
parameter initialization because there is none: the arguments in the outer
CXXConstructExpr directly initialize the parameters of the base class
constructor, and no copies are made. (Making a copy of the parameter is
incorrect, at least if it's done in an observable way.) The derived class
constructor doesn't even exist in the formal model.
E.g., in:

struct X { X *p = this; ~X() {} };
struct A { A(X x) : b(x.p == &x) {} bool b; };
struct B : A { using A::A; };
B b = X{};

... b.b is initialized to true.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D75678

Files:
  clang/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp
  clang/test/Analysis/cxx-inherited-ctor-init-expr.cpp


Index: clang/test/Analysis/cxx-inherited-ctor-init-expr.cpp
===================================================================
--- clang/test/Analysis/cxx-inherited-ctor-init-expr.cpp
+++ clang/test/Analysis/cxx-inherited-ctor-init-expr.cpp
@@ -57,3 +57,19 @@
   clang_analyzer_eval(b.z == 3); // expected-warning{{TRUE}}
 }
 } // namespace arguments_with_constructors
+
+namespace inherited_constructor_crash {
+class a {
+public:
+  a(int);
+};
+struct b : a {
+  using a::a; // Ihnerited ctor.
+};
+void c() {
+  int d;
+  // This construct expr utilizes the inherited ctor.
+  // Note that d must be uninitialized to cause the crash.
+  (b(d)); // expected-warning{{1st function call argument is an uninitialized value}}
+}
+} // namespace inherited_constructor_crash
Index: clang/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp
===================================================================
--- clang/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp
+++ clang/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp
@@ -504,6 +504,27 @@
   if (VisitedAsTopLevel.count(D))
     return true;
 
+  // Skip analysis of inherited constructors as top-level functions because we
+  // cannot model the parameters.
+  //
+  // CXXInheritedCtorInitExpr doesn't take arguments and doesn't model
+  // parameter initialization because there is none: the arguments in the outer
+  // CXXConstructExpr directly initialize the parameters of the base class
+  // constructor, and no copies are made. (Making a copy of the parameter is
+  // incorrect, at least if it's done in an observable way.) The derived class
+  // constructor doesn't even exist in the formal model.
+  // E.g., in:
+  //
+  // struct X { X *p = this; ~X() {} };
+  // struct A { A(X x) : b(x.p == &x) {} bool b; };
+  // struct B : A { using A::A; };
+  // B b = X{};
+  //
+  // ... b.b is initialized to true.
+  if (const auto *CD = dyn_cast<CXXConstructorDecl>(D))
+    if (CD->isInheritingConstructor())
+      return true;
+
   // We want to re-analyse the functions as top level in the following cases:
   // - The 'init' methods should be reanalyzed because
   //   ObjCNonNilReturnValueChecker assumes that '[super init]' never returns


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