74 lines
1.9 KiB
C++
74 lines
1.9 KiB
C++
// RUN: %clang_cc1 -fsyntax-only -Wnrvo -Wno-return-mismatch -verify %s
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struct MyClass {
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int value;
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int c;
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MyClass(int v) : value(v), c(0) {}
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MyClass(const MyClass& other) : value(other.value) { c++; }
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};
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MyClass create_object(bool condition) {
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MyClass obj1(1);
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MyClass obj2(2);
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if (condition) {
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return obj1; // expected-warning{{not eliding copy on return}}
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}
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return obj2; // expected-warning{{not eliding copy on return}}
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}
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MyClass create_object2(){
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MyClass obj(1);
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return obj; // no warning
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}
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template<typename T>
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T create_object3(){
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T obj(1);
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return obj; // no warning
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}
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// Known issue: if a function template uses a
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// deduced return type (i.e. auto or decltype(auto)),
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// then NRVO is not applied for any instantiation of
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// that function template
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// (see https://github.com/llvm/llvm-project/issues/95280).
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template<typename T>
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auto create_object4(){
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T obj(1);
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return obj; // expected-warning{{not eliding copy on return}}
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}
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template<bool F>
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MyClass create_object5(){
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MyClass obj1(1);
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if constexpr (F){
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MyClass obj2(2);
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return obj2; // no warning
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}
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// Missed NRVO optimization by clang
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return obj1; // expected-warning{{not eliding copy on return}}
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}
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constexpr bool Flag = false;
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MyClass create_object6(){
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MyClass obj1(1);
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if constexpr (Flag){
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MyClass obj2(2);
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return obj2; // expected-warning{{not eliding copy on return}}
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}
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return obj1; // no warning
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}
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void create_object7(){
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if constexpr (Flag){
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MyClass obj1(1);
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return obj1; // no warning
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}
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}
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void init_templates(){
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create_object3<MyClass>(); // no warning
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create_object4<MyClass>(); // expected-note {{in instantiation of function template specialization 'create_object4<MyClass>' requested here}}
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create_object5<false>(); // expected-note {{in instantiation of function template specialization 'create_object5<false>' requested here}}
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}
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