[Repo Assist] Fix FormatException when #if directive appears in mutually recursive type definition

[github-actions]

🤖 This PR was created by Repo Assist, an automated AI assistant.

Closes #3174
Supersedes #3290 (rebased on current main after the lambda refactor in #3303)

Root Cause

When an and type definition has compiler directives (#if/#endif) between its attribute lists, two separate bugs interact to cause a FormatException:

1. genOnelinerAttributes was flattening all AttributeListNode lists into a single combined [(Attr1)][(Attr2)] render, silently dropping the ContentBefore trivia (the #if/#endif directives) of all but the first list. mergeMultipleFormatResults then saw different hash-fragment counts across define variants and threw:

   System.FormatException: Fantomas is trying to format the input multiple times...
   [] has 5 fragments
   [NET5_0_OR_GREATER] has 3 fragments
   

2. genTypeDefn did not indent the and header when attributes contain directives, which could produce invalid F# in some define paths (e.g. and\n[(Attr)] Y = int at column 0 is a parse error).

Fix

genOnelinerAttributes: detect when any attribute list after the first has a TriviaContent.Directive in its ContentBefore. In that case, render each AttributeListNode individually via genNode (preserving directives) separated by newlines, rather than flattening into a single node. The common (no-directive) case is unchanged.

genTypeDefn: add hasAttributeDirectivesForAndDefinition check. When an and definition has directive trivia in its attribute lists, set shouldIndentAfterKeyword = true to indent the header — the same treatment already applied when there are directives after the leading keyword identifier (hasTriviaAfterLeadingKeyword).

Example

Before (throws FormatException):

type X = int
and
#if NET5_0_OR_GREATER
    [(NotAValue)]
#endif
    [(Attribute)] Y = int

After:

type X = int

and
#if NET5_0_OR_GREATER
    [(NotAValue)]
#endif
    [(Attribute)] Y = int

Trade-offs

• Minimal change: only genOnelinerAttributes and genTypeDefn are modified
• The fast path (no directives between attribute lists) is unchanged — no performance impact
• Existing behaviour for and definitions without directives is unchanged

Test Status

• ✅ Build: succeeded (0 warnings, 0 errors)
• ✅ Tests: 2770 passed, 7 skipped, 0 failed
• ✅ New regression test added: #if in mutually recursive type definition does not throw FormatException, 3174
• ✅ Reproduction from issue no longer throws FormatException

Generated by Repo Assist

Generated by Repo Assist · ◷

To install this agentic workflow, run

gh aw add githubnext/agentics/workflows/repo-assist.md@4957663821dbb3260348084fa2f1659701950fef