Have LoopConvert use 'auto &&' where necessary

For iterators where the dereference operator returns by value, LoopConvert
should use 'auto &&' in the range-based for loop expression.

If the dereference operator returns an rvalue reference, this is deemed too
strange and the for loop is not converted.

Moved test case from iterator_failing.cpp to iterator.cpp and added extra
tests.

Fixes PR15437.

Reviewer: gribozavr
llvm-svn: 176631

3 files changed, 55 insertions, 15 deletions

diff --git a/clang-tools-extra/test/cpp11-migrate/LoopConvert/Inputs/structures.h b/clang-tools-extra/test/cpp11-migrate/LoopConvert/Inputs/structures.h
index 3379b05ac1e..e37f2b54794 100644
--- a/clang-tools-extra/test/cpp11-migrate/LoopConvert/Inputs/structures.h
+++ b/clang-tools-extra/test/cpp11-migrate/LoopConvert/Inputs/structures.h
@@ -150,4 +150,27 @@ struct PtrSet {
   iterator end() const;
 };
 
+template <typename T>
+struct TypedefDerefContainer {
+  struct iterator {
+    typedef T &deref_type;
+    bool operator!=(const iterator &other) const;
+    deref_type operator*();
+    iterator &operator++();
+  };
+  iterator begin() const;
+  iterator end() const;
+};
+
+template <typename T>
+struct RValueDerefContainer {
+  struct iterator {
+    typedef T &&deref_type;
+    bool operator!=(const iterator &other) const;
+    deref_type operator*();
+    iterator &operator++();
+  };
+  iterator begin() const;
+  iterator end() const;
+};
 #endif  // STRUCTURES_H
diff --git a/clang-tools-extra/test/cpp11-migrate/LoopConvert/iterator.cpp b/clang-tools-extra/test/cpp11-migrate/LoopConvert/iterator.cpp
index a59a90fbfa1..fc36e07fe8b 100644
--- a/clang-tools-extra/test/cpp11-migrate/LoopConvert/iterator.cpp
+++ b/clang-tools-extra/test/cpp11-migrate/LoopConvert/iterator.cpp
@@ -1,5 +1,5 @@
 // RUN: grep -Ev "// *[A-Z-]+:" %s > %t.cpp
-// RUN: cpp11-migrate -loop-convert %t.cpp -- -I %S/Inputs
+// RUN: cpp11-migrate -loop-convert %t.cpp -- -I %S/Inputs -std=c++11
 // RUN: FileCheck -input-file=%t.cpp %s
 // RUN: cpp11-migrate -loop-convert %t.cpp -risk=risky -- -I %S/Inputs
 // RUN: FileCheck -check-prefix=RISKY -input-file=%t.cpp %s
@@ -101,6 +101,37 @@ void f() {
   }
   // CHECK: for ({{[a-zA-Z_ ]*&? ?}}[[VAR:[a-z_]+]] : intmap)
   // CHECK-NEXT: printf("intmap[%d] = %d", [[VAR]].first, [[VAR]].second);
+
+  // PtrSet's iterator dereferences by value so auto & can't be used.
+  {
+    PtrSet<int*> int_ptrs;
+    for (PtrSet<int*>::iterator I = int_ptrs.begin(),
+         E = int_ptrs.end(); I != E; ++I) {
+      // CHECK: for (auto && int_ptr : int_ptrs) {
+    }
+  }
+
+  // This container uses an iterator where the derefence type is a typedef of
+  // a reference type. Make sure non-const auto & is still used. A failure here
+  // means canonical types aren't being tested.
+  {
+    TypedefDerefContainer<int> int_ptrs;
+    for (TypedefDerefContainer<int>::iterator I = int_ptrs.begin(),
+         E = int_ptrs.end(); I != E; ++I) {
+      // CHECK: for (auto & int_ptr : int_ptrs) {
+    }
+  }
+
+  {
+    // Iterators returning an rvalue reference should disqualify the loop from
+    // transformation.
+    RValueDerefContainer<int> container;
+    for (RValueDerefContainer<int>::iterator I = container.begin(),
+         E = container.end(); I != E; ++I) {
+      // CHECK: for (RValueDerefContainer<int>::iterator I = container.begin(),
+      // CHECK-NEXT: E = container.end(); I != E; ++I) {
+    }
+  }
 }
 
 // Tests to ensure that an implicit 'this' is picked up as the container.
diff --git a/clang-tools-extra/test/cpp11-migrate/LoopConvert/iterator_failing.cpp b/clang-tools-extra/test/cpp11-migrate/LoopConvert/iterator_failing.cpp
deleted file mode 100644
index 5684497f745..00000000000
--- a/clang-tools-extra/test/cpp11-migrate/LoopConvert/iterator_failing.cpp
+++ /dev/null
@@ -1,14 +0,0 @@
-// RUN: grep -Ev "// *[A-Z-]+:" %s > %t.cpp
-// RUN: cpp11-migrate -loop-convert %t.cpp -- -I %S/Inputs
-// RUN: FileCheck -input-file=%t.cpp %s
-// XFAIL: *
-#include "structures.h"
-
-void f() {
-  // See PR15437 for details.
-  PtrSet<int*> int_ptrs;
-  for (PtrSet<int*>::iterator I = int_ptrs.begin(),
-       E = int_ptrs.end(); I != E; ++I) {
-    // CHECK: for (const auto & int_ptr : int_ptrs) {
-  }
-}