[clang] [clang-format] Fix a bug in TCAS_Leave using tabs for indentation (PR #98427)

[Owen Pan via cfe-commits]

https://github.com/owenca created https://github.com/llvm/llvm-project/pull/98427

Fixes #92530.

>From fa1da3d06ed2207902df4911933bd40f0d514e51 Mon Sep 17 00:00:00 2001
From: Owen Pan <owenpiano at gmail.com>
Date: Wed, 10 Jul 2024 20:52:18 -0700
Subject: [PATCH] [clang-format] Fix a bug in TCAS_Leave using tabs for
 indentation

Fixes #92530.
---
 clang/lib/Format/WhitespaceManager.cpp        |  2 +-
 clang/unittests/Format/FormatTestComments.cpp | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Format/WhitespaceManager.cpp b/clang/lib/Format/WhitespaceManager.cpp
index 50531aee9d597..a31874a7c3195 100644
--- a/clang/lib/Format/WhitespaceManager.cpp
+++ b/clang/lib/Format/WhitespaceManager.cpp
@@ -1116,7 +1116,7 @@ void WhitespaceManager::alignTrailingComments() {
       // leave the comments.
       if (RestoredLineLength >= Style.ColumnLimit && Style.ColumnLimit > 0)
         break;
-      C.Spaces = OriginalSpaces;
+      C.Spaces = C.NewlinesBefore > 0 ? C.Tok->OriginalColumn : OriginalSpaces;
       continue;
     }
 
diff --git a/clang/unittests/Format/FormatTestComments.cpp b/clang/unittests/Format/FormatTestComments.cpp
index 3e75707a9faec..8f84d59cbb2e2 100644
--- a/clang/unittests/Format/FormatTestComments.cpp
+++ b/clang/unittests/Format/FormatTestComments.cpp
@@ -3145,6 +3145,23 @@ TEST_F(FormatTestComments, AlignTrailingCommentsLeave) {
                    "int bar = 1234;       // This is a very long comment\n"
                    "          // which is wrapped arround.",
                    Style));
+
+  Style = getLLVMStyle();
+  Style.AlignTrailingComments.Kind = FormatStyle::TCAS_Leave;
+  Style.TabWidth = 2;
+  Style.UseTab = FormatStyle::UT_ForIndentation;
+  verifyNoChange("{\n"
+                 "\t// f\n"
+                 "\tf();\n"
+                 "\n"
+                 "\t// g\n"
+                 "\tg();\n"
+                 "\t{\n"
+                 "\t\t// h();  // h\n"
+                 "\t\tfoo();  // foo\n"
+                 "\t}\n"
+                 "}",
+                 Style);
 }
 
 TEST_F(FormatTestComments, DontAlignNamespaceComments) {