858b56e496
This PR is proposing a fix for https://github.com/llvm/llvm-project/issues/65971. Previously, given a coroutine like this ``` task foo(int a) { co_return; } ``` Parameter `a` is never used. However, because C++ coroutines move constructs the variable to a heap allocated coroutine activation frame, we considered all parameters referenced. When diagnosing unused parameters, we cannot distinguish if the variable reference was due to coroutine parameter moves. Compiler Explorer shows that GCC warns against this case correctly, but clang does not: https://godbolt.org/z/Wo7dfqeaf This patch addresses this issue by preserving the original `ParmVarDecl`'s `Referenced` state.
35 lines
809 B
C++
35 lines
809 B
C++
// RUN: %clang_cc1 -fsyntax-only -Wunused-parameter -verify -std=c++20 %s
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#include "Inputs/std-coroutine.h"
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struct awaitable {
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bool await_ready() noexcept;
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void await_resume() noexcept;
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void await_suspend(std::coroutine_handle<>) noexcept;
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};
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struct task : awaitable {
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struct promise_type {
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task get_return_object() noexcept;
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awaitable initial_suspend() noexcept;
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awaitable final_suspend() noexcept;
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void unhandled_exception() noexcept;
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void return_void() noexcept;
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};
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};
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task foo(int a) { // expected-warning{{unused parameter 'a'}}
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co_return;
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}
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task bar(int a, int b) { // expected-warning{{unused parameter 'b'}}
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a = a + 1;
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co_return;
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}
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void create_closure() {
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auto closure = [](int c) -> task { // expected-warning{{unused parameter 'c'}}
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co_return;
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};
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}
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