llvm/llvm-project

Decomposition Declaration diagnostic for missing initializer is pretty unclear

クローズ

#90,107 opened on 2024/04/25

 (9 件のコメント) (0 件のリアクション) (0 人の担当者)C++ (10,782 件のフォーク)batch import
clang:diagnosticsgood first issuequality-of-implementation

Repository metrics

Stars
 (26,378 個のスター)
PR merge metrics
 (平均マージ 1d 2h) (30d で 1,000 merged PRs)

説明

Given the following code:

#include <utility>

std::pair<int, double> MyFunc();

void foo() {
    auto [A, B] C = MyFunc();
}

Our diagnostic is just:

<source>:9:10: error: decomposition declaration '[A, B]' requires an initializer
    9 |     auto [A, B] C = MyFunc();
      |          ^
<source>:9:16: error: expected ';' at end of declaration
    9 |     auto [A, B] C = MyFunc();
      |                ^
      |                ;
2 errors generated.
Compiler returned: 1

https://godbolt.org/z/h9zKT5zGe

No compilers are particularly good at this diagnostic, but all the others at least highlight the C as the mistake, whereas Clang's error is pretty opaque/points at the opening bracket.

I'd prefer we move the 'arrow' to the position where the initializer is expected. Additionally, some improved diagnostic wording that highlights what went wrong better would be appreciated.

コントリビューターガイド