[clang] [clang-format] Don't sort qualifiers across preprocessor directives (PR #81958)

[Owen Pan via cfe-commits]

https://github.com/owenca created https://github.com/llvm/llvm-project/pull/81958

Fixes #80579.

>From 13614f5760a26ba6134abdd555176a1aa2ed3974 Mon Sep 17 00:00:00 2001
From: Owen Pan <owenpiano at gmail.com>
Date: Thu, 15 Feb 2024 17:37:44 -0800
Subject: [PATCH] [clang-format] Don't sort qualifiers across preprocessor
 directives

Fixes #80579.
---
 clang/lib/Format/QualifierAlignmentFixer.cpp  |  2 ++
 clang/unittests/Format/QualifierFixerTest.cpp | 13 +++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/clang/lib/Format/QualifierAlignmentFixer.cpp b/clang/lib/Format/QualifierAlignmentFixer.cpp
index 84941746f0df71..0c63d330b5aed4 100644
--- a/clang/lib/Format/QualifierAlignmentFixer.cpp
+++ b/clang/lib/Format/QualifierAlignmentFixer.cpp
@@ -561,6 +561,8 @@ void LeftRightQualifierAlignmentFixer::fixQualifierAlignment(
 
     for (const auto *Tok = First; Tok && Tok != Last && Tok->Next;
          Tok = Tok->Next) {
+      if (Tok->MustBreakBefore)
+        break;
       if (Tok->is(tok::comment))
         continue;
       if (RightAlign) {
diff --git a/clang/unittests/Format/QualifierFixerTest.cpp b/clang/unittests/Format/QualifierFixerTest.cpp
index 0aa755acfc8213..43476aea66337b 100644
--- a/clang/unittests/Format/QualifierFixerTest.cpp
+++ b/clang/unittests/Format/QualifierFixerTest.cpp
@@ -1177,6 +1177,19 @@ TEST_F(QualifierFixerTest, DontPushQualifierThroughNonSpecifiedTypes) {
   verifyFormat("const inline static Foo;", Style);
 }
 
+TEST_F(QualifierFixerTest, QualifiersBrokenUpByPPDirectives) {
+  auto Style = getLLVMStyle();
+  Style.QualifierAlignment = FormatStyle::QAS_Custom;
+  Style.QualifierOrder = {"constexpr", "inline", "type"};
+
+  verifyFormat("inline\n"
+               "#if FOO\n"
+               "    constexpr\n"
+               "#endif\n"
+               "    int i = 0;",
+               Style);
+}
+
 TEST_F(QualifierFixerTest, UnsignedQualifier) {
 
   FormatStyle Style = getLLVMStyle();