Suboptimal formatting of `let`-bound chains of `||` with `==` inside them.

Input

                    let assign_to_field =
                        context == PlaceContext::MutatingUse(MutatingUseContext::Store)
                        || context == PlaceContext::MutatingUse(MutatingUseContext::Drop)
                        || context == PlaceContext::MutatingUse(MutatingUseContext::AsmOutput);

Output

                    let assign_to_field = context
                        == PlaceContext::MutatingUse(MutatingUseContext::Store)
                        || context == PlaceContext::MutatingUse(MutatingUseContext::Drop)
                        || context == PlaceContext::MutatingUse(MutatingUseContext::AsmOutput);

Expected output

                    let assign_to_field =
                        context == PlaceContext::MutatingUse(MutatingUseContext::Store)
                        || context == PlaceContext::MutatingUse(MutatingUseContext::Drop)
                        || context == PlaceContext::MutatingUse(MutatingUseContext::AsmOutput);

The reformatting actually makes the code look worse (linebreak in the middle of one of the comparisons) without a need (such as a line being too long).

Meta

• This is via ./x.py fmt in current rustc

Reproduce the formatting difference from the issue using ./x.py fmt and compare the shown input, output, and expected output. Trace the formatter behavior for let-bound chains of || containing == expressions, then add coverage for the expected layout and confirm ./x.py fmt produces it without unnecessary breaks.