[matt-edmondson]

Fixes #158

What changed

TemplateRendering.WriteExpressionBody, which PropertyTemplate.ExpressionBodyFactory and AccessorKind.Expression share, now handles preprocessor directives:

• A directive that opens the expression is no longer written on the declaration line. The line ends at => and the directive starts the next line, which avoids CS1040.
• A directive after the last line of code moves the semicolon. The last line of code may sit in one branch of an #if, so terminating it would leave the other branches unterminated. When any directive follows that line, the ; goes on a line of its own after the last directive, where every branch reaches it. This avoids #endif; (CS1025) and leaves no branch without a terminator.
• When code follows the last directive, that code is terminated as before. Comment-only lines are still skipped, as An expression body whose last line ends in a // comment gets its semicolon inside the comment: public int P => x // note; does not compile (CS1002) #144 introduced.

The repro now renders:

int P =>
#if DEBUG
1
#else
2
#endif
;

The issue's example form, with the ; inside each branch, was one option it offered. A trailing ; after the directives is correct whether the branches are complete expressions or fragments of one, such as 1 #if DEBUG + 2 #endif. Terminating inside each branch would break that second case.

Tests

• New tests cover the repro through ExpressionBodyFactory and through AccessorKind.Expression, plus an expression that ends in a conditional after code on the arrow line.
• A regression guard covers code after the last directive, which still gets its own ;.
• With the fix reverted, the three directive tests fail.
• The full suite passes: 253 tests on net10.0. The library builds with no warnings on every target framework.
• This branch merges cleanly with Refuse a line break in a doc comment cref or name before writing [patch] #160 and Brace a member body that holds only comments or directives [patch] #161.

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Generated by Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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