1 files changed, 183 insertions, 0 deletions
diff --git a/clang-tools-extra/test/clang-tidy/performance-inefficient-vector-operation.cpp b/clang-tools-extra/test/clang-tidy/performance-inefficient-vector-operation.cpp
new file mode 100644
index 00000000000..f51c4690a25
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/performance-inefficient-vector-operation.cpp
@@ -0,0 +1,183 @@
+// RUN: %check_clang_tidy %s performance-inefficient-vector-operation %t -- -format-style=llvm --
+
+typedef int size_t;
+
+namespace std {
+template <class T>
+class vector {
+ public:
+  typedef T* iterator;
+  typedef const T* const_iterator;
+  typedef T& reference;
+  typedef const T& const_reference;
+  typedef size_t size_type;
+
+  explicit vector();
+  explicit vector(size_type n);
+
+  void push_back(const T& val);
+  void reserve(size_t n);
+  void resize(size_t n);
+
+  size_t size();
+  const_reference operator[] (size_type) const;
+  reference operator[] (size_type);
+};
+} // namespace std
+
+void f(std::vector<int>& t) {
+  {
+    std::vector<int> v;
+    // CHECK-FIXES: v.reserve(10);
+    for (int i = 0; i < 10; ++i)
+      v.push_back(i);
+      // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: 'push_back' is called inside a loop; consider pre-allocating the vector capacity before the loop
+  }
+  {
+    std::vector<int> v;
+    // CHECK-FIXES: v.reserve(10);
+    for (int i = 0; i < 10; i++)
+      v.push_back(i);
+      // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: 'push_back' is called
+  }
+  {
+    std::vector<int> v;
+    // CHECK-FIXES: v.reserve(10);
+    for (int i = 0; i < 10; ++i)
+      v.push_back(0);
+      // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: 'push_back' is called
+  }
+  {
+    std::vector<int> v;
+    // CHECK-FIXES: v.reserve(5);
+    for (int i = 0; i < 5; ++i) {
+      v.push_back(i);
+      // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: 'push_back' is called
+    }
+    // CHECK-FIXES-NOT: v.reserve(10);
+    for (int i = 0; i < 10; ++i) {
+      // No fix for this loop as we encounter the prior loops.
+      v.push_back(i);
+    }
+  }
+  {
+    std::vector<int> v;
+    std::vector<int> v2;
+    v2.reserve(3);
+    // CHECK-FIXES: v.reserve(10);
+    for (int i = 0; i < 10; ++i)
+      v.push_back(i);
+      // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: 'push_back' is called
+  }
+  {
+    std::vector<int> v;
+    // CHECK-FIXES: v.reserve(t.size());
+    for (size_t i = 0; i < t.size(); ++i) {
+      v.push_back(t[i]);
+      // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: 'push_back' is called
+    }
+  }
+  {
+    std::vector<int> v;
+    // CHECK-FIXES: v.reserve(t.size() - 1);
+    for (size_t i = 0; i < t.size() - 1; ++i) {
+      v.push_back(t[i]);
+    } // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: 'push_back' is called
+  }
+
+  // ---- Non-fixed Cases ----
+  {
+    std::vector<int> v;
+    v.reserve(20);
+    // CHECK-FIXES-NOT: v.reserve(10);
+    // There is a "reserve" call already.
+    for (int i = 0; i < 10; ++i) {
+      v.push_back(i);
+    }
+  }
+  {
+    std::vector<int> v;
+    v.reserve(5);
+    // CHECK-FIXES-NOT: v.reserve(10);
+    // There is a "reserve" call already.
+    for (int i = 0; i < 10; ++i) {
+      v.push_back(i);
+    }
+  }
+  {
+    std::vector<int> v;
+    v.resize(5);
+    // CHECK-FIXES-NOT: v.reserve(10);
+    // There is a ref usage of v before the loop.
+    for (int i = 0; i < 10; ++i) {
+      v.push_back(i);
+    }
+  }
+  {
+    std::vector<int> v;
+    v.push_back(0);
+    // CHECK-FIXES-NOT: v.reserve(10);
+    // There is a ref usage of v before the loop.
+    for (int i = 0; i < 10; ++i) {
+      v.push_back(i);
+    }
+  }
+  {
+    std::vector<int> v;
+    f(v);
+    // CHECK-FIXES-NOT: v.reserve(10);
+    // There is a ref usage of v before the loop.
+    for (int i = 0; i < 10; ++i) {
+      v.push_back(i);
+    }
+  }
+  {
+    std::vector<int> v(20);
+    // CHECK-FIXES-NOT: v.reserve(10);
+    // v is not constructed with default constructor.
+    for (int i = 0; i < 10; ++i) {
+      v.push_back(i);
+    }
+  }
+  {
+    std::vector<int> v;
+    // CHECK-FIXES-NOT: v.reserve(10);
+    // For-loop is not started with 0.
+    for (int i = 1; i < 10; ++i) {
+      v.push_back(i);
+    }
+  }
+  {
+    std::vector<int> v;
+    // CHECK-FIXES-NOT: v.reserve(t.size());
+    // v isn't referenced in for-loop body.
+    for (size_t i = 0; i < t.size(); ++i) {
+      t.push_back(i);
+    }
+  }
+  {
+    std::vector<int> v;
+    int k;
+    // CHECK-FIXES-NOT: v.reserve(10);
+    // For-loop isn't a fixable loop.
+    for (size_t i = 0; k < 10; ++i) {
+      v.push_back(t[i]);
+    }
+  }
+  {
+    std::vector<int> v;
+    // CHECK-FIXES-NOT: v.reserve(i + 1);
+    // The loop end expression refers to the loop variable i.
+    for (int i = 0; i < i + 1; i++)
+      v.push_back(i);
+  }
+  {
+    std::vector<int> v;
+    int k;
+    // CHECK-FIXES-NOT: v.reserve(10);
+    // For-loop isn't a fixable loop.
+    for (size_t i = 0; i < 10; ++k) {
+      v.push_back(t[i]);
+    }
+  }
+}