[clang] clang-format: ensure ternary operands are aligned (PR #196697)

[Eugene Shalygin via cfe-commits]

https://github.com/zeule updated https://github.com/llvm/llvm-project/pull/196697

>From a0d72baa701df3dee6364bd3948b8d9877d1bd24 Mon Sep 17 00:00:00 2001
From: Eugene Shalygin <eugene.shalygin at gmail.com>
Date: Sat, 9 May 2026 09:06:41 +0200
Subject: [PATCH] clang-format: ensure ternary operands are aligned

Set ParentState::AlignedTo for ternary operands.
---
 clang/lib/Format/ContinuationIndenter.cpp | 15 +++++++++++++++
 clang/unittests/Format/AlignmentTest.cpp  | 10 ++++++++++
 2 files changed, 25 insertions(+)

diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index b2f799bb33b01..5cd771cacc193 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -1276,6 +1276,21 @@ unsigned ContinuationIndenter::addTokenOnNewLine(LineState &State,
     CurrentState.BreakBeforeParameter = false;
     CurrentState.AlignedTo = &Current;
   }
+  if (!CurrentState.AlignedTo && Current.is(TT_ConditionalExpr)) {
+    switch (Style.AlignOperands) {
+    case FormatStyle::OAS_DontAlign:
+      break;
+    case FormatStyle::OAS_Align:
+      CurrentState.AlignedTo = Current.is(tok::question)
+                                   ? Current.getPrevious(tok::equal)
+                                   : Current.getPrevious(tok::question);
+      break;
+    case FormatStyle::OAS_AlignAfterOperator:
+      if (Current.is(tok::colon))
+        CurrentState.AlignedTo = Current.getPrevious(tok::question);
+      break;
+    }
+  }
 
   if (!DryRun) {
     unsigned MaxEmptyLinesToKeep = Style.MaxEmptyLinesToKeep + 1;
diff --git a/clang/unittests/Format/AlignmentTest.cpp b/clang/unittests/Format/AlignmentTest.cpp
index 971ceeefef582..9421a4c933b9e 100644
--- a/clang/unittests/Format/AlignmentTest.cpp
+++ b/clang/unittests/Format/AlignmentTest.cpp
@@ -3599,6 +3599,16 @@ TEST_F(AlignmentTest, ContinuedAligned) {
                "\t},\n"
                "\tvariant);",
                Style);
+
+  Style.ColumnLimit = 40;
+  Style.IndentWidth = Style.TabWidth = Style.ContinuationIndentWidth = 8;
+
+  verifyFormat("void f() {\n"
+               "\tint aaaaaaaaaaaaaaaaaaaa =\n"
+               "\t\t000000000000000001 ? 2\n"
+               "\t\t                   : 3;\n"
+               "}",
+               Style);
 }
 
 } // namespace