Add testcase for template-spills

We've seen a lot of problems with template instantiations, that IWYU
mistakenly attributes implementation details in the template to the
instantiation location.

This testcase replicates a few common standard library constructs that
keep triggering this:

* Constructor uses unrelated type (Inner<T> does sizeof(detail::Detail))
* Constructor body uses try/catch (Inner<T> catches Inner<T>)
* Constructor body uses range for (Inner<T> iterates over itself)
* Operator overloads returning nested composite types (Outer returns
  Inner<T>::value_type)

There are other type reporting constructs as well, but they are harder
to exercise succinctly. Assume all type reporting is covered by the same
mechanics, so we can use this as a trigger for regressions.

4 files changed, 89 insertions, 0 deletions

diff --git a/tests/cxx/tpl_spill_nested-d1.h b/tests/cxx/tpl_spill_nested-d1.h
new file mode 100644
index 0000000..56da901
--- /dev/null
+++ b/tests/cxx/tpl_spill_nested-d1.h
@@ -0,0 +1,19 @@
+//===--- tpl_spill_nested-d1.h - test input file for iwyu ------*- C++ -*--===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "tests/cxx/tpl_spill_nested-d2.h"
+
+template <class T>
+struct Outer {
+  Inner<T> inner;
+
+  typename Inner<T>::value_type& operator[](int index) {
+    return *(inner.begin() + index);
+  }
+};
diff --git a/tests/cxx/tpl_spill_nested-d2.h b/tests/cxx/tpl_spill_nested-d2.h
new file mode 100644
index 0000000..697e09f
--- /dev/null
+++ b/tests/cxx/tpl_spill_nested-d2.h
@@ -0,0 +1,32 @@
+//===--- tpl_spill_nested-d2.h - test input file for iwyu ------*- C++ -*--===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "tests/cxx/tpl_spill_nested-d3.h"
+
+template <class T>
+struct Inner {
+  typedef T value_type;
+  typedef value_type* iterator;
+  iterator begin();
+  iterator end();
+
+  Inner()
+      // Use an internal type.
+      : size(sizeof(detail::Detail)) {
+    // Throw in a few statements that exercise type reporting.
+    try {
+    } catch (const Inner<T>&) {
+    }
+
+    for (const value_type& x : *this) {
+    }
+  }
+
+  unsigned long long size;
+};
diff --git a/tests/cxx/tpl_spill_nested-d3.h b/tests/cxx/tpl_spill_nested-d3.h
new file mode 100644
index 0000000..5554d7f
--- /dev/null
+++ b/tests/cxx/tpl_spill_nested-d3.h
@@ -0,0 +1,12 @@
+//===--- tpl_spill_nested-d3.h - test input file for iwyu ------*- C++ -*--===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+namespace detail {
+struct Detail {};
+}  // namespace detail
diff --git a/tests/cxx/tpl_spill_nested.cc b/tests/cxx/tpl_spill_nested.cc
new file mode 100644
index 0000000..9ffd1ce
--- /dev/null
+++ b/tests/cxx/tpl_spill_nested.cc
@@ -0,0 +1,26 @@
+//===--- tpl_spill_nested.cc - test input file for iwyu -------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "tests/cxx/tpl_spill_nested-d1.h"
+
+// IWYU_ARGS: -I .
+
+void Instantiate() {
+  // No diagnostic expected.
+  Outer<int> o;
+
+  // No diagnostic expected.
+  o[100] = 1;
+}
+
+/**** IWYU_SUMMARY
+
+(tests/cxx/tpl_spill_nested.cc has correct #includes/fwd-decls)
+
+***** IWYU_SUMMARY */