From 8e85739a5f24e34cb22768fe6ef33b593ed054df Mon Sep 17 00:00:00 2001
From: Owen Pan <owenpiano@gmail.com>
Date: Sun, 18 Jun 2023 23:18:00 -0700
Subject: [PATCH] [clang-format] Don't finalize #if, #else, #endif, etc.

Don't finalize a preprocessor branch directive if it's the first
token of an annotated line. See the rationale at
https://reviews.llvm.org/D150057#inline-1449546.

Fixes #63379

Differential Revision: https://reviews.llvm.org/D153243
---
 clang/lib/Format/UnwrappedLineFormatter.cpp | 12 ++++++++++--
 clang/lib/Format/WhitespaceManager.cpp      | 10 +---------
 clang/unittests/Format/FormatTest.cpp       |  7 +++++++
 3 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/clang/lib/Format/UnwrappedLineFormatter.cpp b/clang/lib/Format/UnwrappedLineFormatter.cpp
index 6d9a43d..3eacd020 100644
--- a/clang/lib/Format/UnwrappedLineFormatter.cpp
+++ b/clang/lib/Format/UnwrappedLineFormatter.cpp
@@ -1411,8 +1411,16 @@ unsigned UnwrappedLineFormatter::format(
       NextLine = Joiner.getNextMergedLine(DryRun, IndentTracker);
       RangeMinLevel = UINT_MAX;
     }
-    if (!DryRun)
-      markFinalized(TheLine.First);
+    if (!DryRun) {
+      auto *Tok = TheLine.First;
+      if (Tok->is(tok::hash) && !Tok->Previous && Tok->Next &&
+          Tok->Next->isOneOf(tok::pp_if, tok::pp_ifdef, tok::pp_ifndef,
+                             tok::pp_elif, tok::pp_elifdef, tok::pp_elifndef,
+                             tok::pp_else, tok::pp_endif)) {
+        Tok = Tok->Next;
+      }
+      markFinalized(Tok);
+    }
   }
   PenaltyCache[CacheKey] = Penalty;
   return Penalty;
diff --git a/clang/lib/Format/WhitespaceManager.cpp b/clang/lib/Format/WhitespaceManager.cpp
index 040b953..2425552 100644
--- a/clang/lib/Format/WhitespaceManager.cpp
+++ b/clang/lib/Format/WhitespaceManager.cpp
@@ -49,16 +49,8 @@ void WhitespaceManager::replaceWhitespace(FormatToken &Tok, unsigned Newlines,
                                           unsigned Spaces,
                                           unsigned StartOfTokenColumn,
                                           bool IsAligned, bool InPPDirective) {
-  auto PPBranchDirectiveStartsLine = [&Tok] {
-    return Tok.is(tok::hash) && !Tok.Previous && Tok.Next &&
-           Tok.Next->isOneOf(tok::pp_if, tok::pp_ifdef, tok::pp_ifndef,
-                             tok::pp_elif, tok::pp_elifdef, tok::pp_elifndef,
-                             tok::pp_else, tok::pp_endif);
-  };
-  if ((Tok.Finalized && !PPBranchDirectiveStartsLine()) ||
-      (Tok.MacroCtx && Tok.MacroCtx->Role == MR_ExpandedArg)) {
+  if (Tok.Finalized || (Tok.MacroCtx && Tok.MacroCtx->Role == MR_ExpandedArg))
     return;
-  }
   Tok.setDecision((Newlines > 0) ? FD_Break : FD_Continue);
   Changes.push_back(Change(Tok, /*CreateReplacement=*/true, Tok.WhitespaceRange,
                            Spaces, StartOfTokenColumn, Newlines, "", "",
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 4c58df8..6b05404 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -23106,6 +23106,13 @@ TEST_F(FormatTest, DisableRegions) {
                "int* j;\n"
                "// clang-format only\n"
                "int* k;");
+
+  verifyNoChange("// clang-format off\n"
+                 "#if 0\n"
+                 "        #if SHOULD_STAY_INDENTED\n"
+                 " #endif\n"
+                 "#endif\n"
+                 "// clang-format on");
 }
 
 TEST_F(FormatTest, DoNotCrashOnInvalidInput) {
-- 
2.7.4