Description
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:
#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:
#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
BasedOnStyle: LLVM
SpaceBeforeParens: Never
SpacesInAngles: Never
AlignConsecutiveDeclarations: trueAnalysis
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.