[AArnott]

Fixes: #4367

SA1143 currently rejects readable expanded conditional expressions when the condition spans multiple lines. Allow multiline conditions in the expanded layout, requiring the ? and : lines to align and be indented beyond the condition's final line. The expanded code fix continues to produce a valid layout by flattening the condition onto one line.

Added regression coverage for the reported layout, the expanded fix, and the existing analyzer tests' invalid indentation case. The regression test fails on master with SA1143 at the ? token. Updated the English and localized SA1143 documentation.

The analyzer's registration is unchanged; the existing conditional-expression callback now uses the condition's last token to determine its indentation. No additional callbacks or work for files without conditional expressions.

[Copilot]

🟡 Changes recommended

Conditions ending in multiline literals use the opening line’s indentation instead of the final line’s indentation.

1 open issue

• Measure condition indentation at multiline literal end · New

What changed in this PR

Updates SA1143 to allow multiline conditions in expanded conditional expressions.

Changes:

• Checks operator indentation against the condition’s last token.
• Adds C# 7 analyzer and expanded-fix regression tests.
• Updates English and localized documentation.

File	Description
test/​StyleCop.Analyzers.Test.CSharp7/​ReadabilityRules/​SA1143CSharp7UnitTests.cs	Adds multiline-condition regression tests.
src/​StyleCop.Analyzers/​ReadabilityRules/​SA1143ConditionalExpressionsMustBeFormattedConsistently.cs	Relaxes expanded-layout validation.
documentation/​zh-cn/​SA1143.md	Updates Chinese guidance and example.
documentation/​SA1143.md	Documents multiline conditions and indentation.
documentation/​ru-ru/​SA1143.md	Updates Russian guidance and example.
documentation/​cs-cz/​SA1143.md	Synchronizes the Czech documentation page.

_{Review effort: Balanced}

[Copilot]

🟡 Changes recommended

Move the C# 6-compatible regression theory into the base test project to cover the oldest supported compiler.

1 open issue

• Move theory to C# 6 project to preserve oldest-compiler coverage · New

1 resolved since last review

• Measure condition indentation at multiline literal end

_{Review effort: Balanced}

[Copilot]

🔵 Needs a closer look

Nested false-branch conditions can bypass the enclosing branch’s continuation-indentation requirement.

1 open issue

• Move theory to C# 6 project to preserve oldest-compiler coverage

1 previously missed issue

In code that hasn't changed since last review

Nested false branches bypass continuation indentation checks

src/​StyleCop.Analyzers/​ReadabilityRules/​SA1143ConditionalExpressionsMustBeFormattedConsistently.cs:100

Allowing multiline conditions also lets nested false branches bypass the enclosing branch's continuation-indentation check. For example, this layout is now accepted:

var x = firstCondition
    ? first
    : left &&
    right
        ? second
        : third;

right is aligned with the outer :, violating the continuation rule documented in documentation/SA1143.md:41–42. IsExpanded advances to next without checking its condition against the outer operator column, and the nested expression's callback is skipped. Validate the nested condition's continuation indentation before advancing, and require its operators to remain deeper than the enclosing operators. Add a regression test for this layout and a correctly indented counterpart.

_{Review effort: Balanced}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.63%. Comparing base (6a9040d) to head (af7d037).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4374   +/-   ##
=======================================
  Coverage   97.63%   97.63%           
=======================================
  Files        1344     1345    +1     
  Lines      151640   151674   +34     
  Branches     5215     5216    +1     
=======================================
+ Hits       148048   148082   +34     
  Misses       2268     2268           
  Partials     1324     1324           

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[bjornhellander]

Allowing multi-line conditions seems fine. It allows for some very unreadable code if misused, but forbidding it seem overly strict. Thumbs up on that one.

The other part about comparing indentation to the condition's last line is something that hasn't clicked for me yet. I would need to dig into that more, and I don't think I will manage that this week.