[clang] [clang-tools-extra] [clang-tidy] New performance linter: performance-inefficient-copy-assign (PR #179467)

[Baranov Victor via cfe-commits]

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@@ -0,0 +1,75 @@
+// RUN: %check_clang_tidy %s performance-inefficient-copy-assign %t
+
+struct NonTrivialMoveAssign {
+  NonTrivialMoveAssign& operator=(const NonTrivialMoveAssign&);
+  NonTrivialMoveAssign& operator=(NonTrivialMoveAssign&&);
+  NonTrivialMoveAssign& operator+=(const NonTrivialMoveAssign&);
+  NonTrivialMoveAssign& operator+=(NonTrivialMoveAssign&&);
+  void stuff();
+};
+
+struct TrivialMoveAssign {
+  TrivialMoveAssign& operator=(const TrivialMoveAssign&);
+  TrivialMoveAssign& operator=(TrivialMoveAssign&&) = default;
+};
+
+struct NoMoveAssign {
+  NoMoveAssign& operator=(const NoMoveAssign&);
+  NoMoveAssign& operator=(NoMoveAssign&&) = delete;
+};
+
+void ConvertibleNonTrivialMoveAssign(NonTrivialMoveAssign& target, NonTrivialMoveAssign source) {
+  // CHECK-MESSAGES: [[@LINE+1]]:{{[0-9]*}}: warning: 'source' could be moved here [performance-inefficient-copy-assign]
+  target = source;
+}
+
+void NonProfitableTrivialMoveAssign(TrivialMoveAssign& target, TrivialMoveAssign source) {
+  // No message expected, moving is possible but pedantic.
+  target = source;
+}
+
+void ConvertibleNonTrivialMoveAssignWithBranching(bool cond, NonTrivialMoveAssign& target, NonTrivialMoveAssign source) {
+  if(cond) {
+    // CHECK-MESSAGES: [[@LINE+1]]:{{[0-9]*}}: warning: 'source' could be moved here [performance-inefficient-copy-assign]
+    target = source;
+  }
----------------
vbvictor wrote:

also with variables that are const/thread_local/extern, etc...
Please refer to cases in https://reviews.llvm.org/D137205 and pick that you are missing.

https://github.com/llvm/llvm-project/pull/179467