| Issue |
74016
|
| Summary |
`-Wundefined-func-template` warns that no definition is available for a pure virtual function
|
| Labels |
clang:frontend,
false-positive
|
| Assignees |
|
| Reporter |
ahatanak
|
The warning seems incorrect as `B::bar` is pure virtual and its definition isn't needed.
$ cat test.cpp
```
template <typename T> class B {
public:
constexpr void foo(const T &) { bar(1); }
virtual constexpr void bar(unsigned int) = 0;
};
template <typename T> class D : public B<T> {
public:
constexpr void bar(unsigned int) override {}
};
void test() {
auto t = D<int>();
t.foo(0);
}
```
$ clang++ -std=c++20 test.cpp -Wundefined-func-template -c
test.cpp:4:35: warning: instantiation of function 'B<int>::bar' required here, but no definition is available [-Wundefined-func-template]
constexpr void foo(const T &) { bar(1); }
^
test.cpp:5:26: note: forward declaration of template entity is here
virtual constexpr void bar(unsigned int) = 0;
^
test.cpp:4:35: note: add an explicit instantiation declaration to suppress this warning if 'B<int>::bar' is explicitly instantiated in another translation unit
constexpr void foo(const T &) { bar(1); }
^
1 warning generated.
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