<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/136541>136541</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang-format] Regression: AlignConsecutiveDeclarations introduces invalid spacing in using declarations with overloaded operators
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang-format
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          kust1011
      </td>
    </tr>
</table>

<pre>
    ### Description

In Clang-format versions 20.1.1 and 20.1.2, enabling `AlignConsecutiveDeclarations` causes incorrect formatting of `using` declarations involving overloaded operators. Specifically, an extra space is inserted between the scope resolution operator `::` and the overloaded operator name, resulting in invalid C++ syntax.

#### Minimal Example

**Input:**

```cpp
#include <vector>

void test1() {
  using std::operator==;
  std::vector<int> v;
}

void test2() {
  using std::operator==;

  std::vector<int> v;
}
```

**Formatted Output with Clang-format 20.1.1 / 20.1.2:**

```cpp
#include <vector>

void test1() {
  using std::      operator==;
  std::vector<int> v;
}

void test2() {
  using std::operator==;

  std::vector<int> v;
}
```


In `test1()`, Clang-format inserts extra whitespace between `::` and `operator==`, producing a non-standard formatting that may be misleading or undesirable in production code. This behavior is triggered when the `using` declaration is followed by another declaration that enables alignment logic (e.g., `std::vector<int> v;`) under the `AlignConsecutiveDeclarations` setting. While the resulting code is still syntactically valid, the formatting contradicts conventional C++ style and may degrade readability or tooling reliability.


#### Style Configuration

```yaml
BasedOnStyle: LLVM
SpaceBeforeParens: Never
SpacesInAngles: Never
AlignConsecutiveDeclarations: true
```

#### Analysis

This issue appears to stem from the alignment logic introduced by `AlignConsecutiveDeclarations`. When multiple declarations are present, Clang-format attempts to align them, treating `operator==` in the `using` declaration as a field to align. This leads to the insertion of spaces within the `using` declaration, breaking the syntax.

Notably, this behavior is a regression from Clang-format 19.1.7, which correctly preserved or corrected the formatting regardless of context.
</pre>
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