[clang-tools-extra] [clang-tidy] Add `performance-explicit-move-constructor` check (PR #122599)

[Julian Schmidt via cfe-commits]

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@@ -0,0 +1,32 @@
+.. title:: clang-tidy - performance-explicit-move-constructor
+
+performance-explicit-move-constructor
+=====================================
+
+Warns when a class defines an explicit move constructor, which may cause
+the copy constructor to get called instead.
+
+Example:
+
+.. code-block:: c++
+
+    class Expensive {
+    public:
+        // ...
+        Expensive(const Expensive&) { /* ... */ }
+        explicit Expensive(Expensive&&) { /* ... */ }
+    };
+
+    void process(Expensive);
+
+    int main() {
+        Expensive exp{};
+        process(std::move(exp));
+
+        return 0;
+    }
+
+Here, the call to ``process`` is actually going to copy ``exp`` instead of
+moving it, potentially incurring a performance penalty if copying is expensive.
+No warning will be emitted if the copy constructor is deleted, as any call to
+it would make the program fail to compile.
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5chmidti wrote:

Nit: missing newline at end of file

https://github.com/llvm/llvm-project/pull/122599