Fix a crash when resolving overloads of C++ virtual methods.

The isOverload() method needs to account for situations where the two
methods being compared don't have the same number of arguments.

rdar://problem/39542960

llvm-svn: 330450

lldb/packages/Python/lldbsuite/test/lang/cpp/virtual-overload/Makefile

@@ -0,0 +1,5 @@
+LEVEL = ../../../make
+
+CXX_SOURCES := main.cpp
+
+include $(LEVEL)/Makefile.rules

lldb/packages/Python/lldbsuite/test/lang/cpp/virtual-overload/TestVirtualOverload.py

@@ -0,0 +1,3 @@
+from lldbsuite.test import lldbinline
+
+lldbinline.MakeInlineTest(__file__, globals())

lldb/packages/Python/lldbsuite/test/lang/cpp/virtual-overload/main.cpp

@@ -0,0 +1,17 @@
+// Test that lldb doesn't get confused by an overload of a virtual
+// function of the same name.
+struct Base {
+  virtual void f(int i) {}
+  virtual ~Base() {}
+};
+
+struct Derived : Base {
+  virtual void f(int i, int j) {}
+};
+
+int main(int argc, char **argv) {
+  Derived obj;
+  obj.f(1, 2); //% self.expect("fr var", "not crashing", substrs = ["obj"])
+  return 0;
+}
+

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

@@ -2170,7 +2170,10 @@ static bool isOverload(clang::CXXMethodDecl *m1, clang::CXXMethodDecl *m2) {
                                  m2p.getUnqualifiedType());
     };
 
-  return !std::equal(m1Type->param_type_begin(), m1Type->param_type_end(),
+  // FIXME: In C++14 and later, we can just pass m2Type->param_type_end()
+  //        as a fourth parameter to std::equal().
+  return (m1->getNumParams() != m2->getNumParams()) ||
+         !std::equal(m1Type->param_type_begin(), m1Type->param_type_end(),
                      m2Type->param_type_begin(), compareArgTypes);
 }