[clang] [clang-format] Reset `Line->IsModuleOrImportDecl` in `addUnwrappedLine` (PR #204565)

[Damian Höster via cfe-commits]

https://github.com/damster101 created https://github.com/llvm/llvm-project/pull/204565

The `IsModuleOrImportDecl` flag was not reset in `addUnwrappedLine`. Since the parser recycles the `Line` object, this flag remained `true` for all subsequent lines in the file, which disabled wrapping (`CanBreakBefore` in `TokenAnnotator.cpp`) for expression-level constructs after any C++20 module or import statement, causing some formatting rules to not be applied in places. This patch fixes the issue by resetting the flag to `false`.

>From d9997828c460931677dbb69eab12f5f44bcd2c7e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Damian=20H=C3=B6ster?= <damian.hoester at posteo.de>
Date: Wed, 17 Jun 2026 14:43:28 +0200
Subject: [PATCH] [clang-format] Reset Line->IsModuleOrImportDecl in
 addUnwrappedLine

The `IsModuleOrImportDecl` flag was not reset in `addUnwrappedLine`. Since the parser recycles the `Line` object, this flag remained `true` for all subsequent lines in the file, which disabled wrapping (`CanBreakBefore` in `TokenAnnotator.cpp`) for expression-level constructs after any C++20 module or import statement.

This patch fixes the issue by resetting the flag to `false` in `addUnwrappedLine()`.
---
 clang/lib/Format/UnwrappedLineParser.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index c83e82674dee1..b3f239a3ee801 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -4718,6 +4718,7 @@ void UnwrappedLineParser::addUnwrappedLine(LineLevel AdjustLevel) {
   Line->FirstStartColumn = 0;
   Line->IsContinuation = false;
   Line->SeenDecltypeAuto = false;
+  Line->IsModuleOrImportDecl = false;
 
   if (ClosesWhitesmithsBlock && AdjustLevel == LineLevel::Remove)
     --Line->Level;