Merge origin/master into fix/2539

Resolve formatter_test.cc conflict by keeping both the #2539
line-continuation port-list regression and the #2542 continuation-
comment tests from master.

verible/common/formatting/align.cc

diff --git a/verible/common/formatting/align.cc b/verible/common/formatting/align.cc
index 74bc432..9f77014 100644
--- a/verible/common/formatting/align.cc
+++ b/verible/common/formatting/align.cc
@@ -1001,6 +1001,20 @@
       auto &line = node.Value();
       auto ftokens = line.TokensRange();
 
+      // Leading non-tree tokens before a forced wrap must stay on their own
+      // line. Putting them in a kInline prolog cell would glue e.g. `//\` onto
+      // the following `input` (GitHub issue 2539). Preserve original spacing
+      // for the whole row instead. Master's scanner already omits those
+      // leading tokens from column bids; this keeps ApplyAlignment from
+      // still inlining them.
+      if (align_actions.front().ftoken != ftokens.begin() &&
+          align_actions.front().ftoken->before.break_decision ==
+              SpacingOptions::kMustWrap) {
+        FormatUsingOriginalSpacing(TokenPartitionRange(*row, std::next(*row)));
+        ++row;
+        continue;
+      }
+
       line.SetPartitionPolicy(PartitionPolicyEnum::kAlreadyFormatted);
 
       verible::TokenPartitionTree *current_cell = nullptr;

verible/verilog/formatting/align.cc

diff --git a/verible/verilog/formatting/align.cc b/verible/verilog/formatting/align.cc
index 6640adb..24696c7 100644
--- a/verible/verilog/formatting/align.cc
+++ b/verible/verilog/formatting/align.cc
@@ -147,6 +147,32 @@
          b == AlignmentGroupBoundary::kBlankLinesAndSeparatorComments;
 }
 
+// True when non-tree tokens (e.g. // comments, line-continuation `\`) precede
+// the origin, and the first origin token must start a new line. Aligning such
+// partitions would glue the leading tokens onto the origin line via kInline
+// cells (GitHub issue 2539). Leave them out of alignment instead.
+static bool PartitionHasLeadingTokensBeforeForcedWrap(
+    const TokenPartitionTree &partition) {
+  const auto &uwline = partition.Value();
+  const verible::Symbol *origin = uwline.Origin();
+  if (origin == nullptr) return false;
+
+  const auto ftokens = uwline.TokensRange();
+  if (ftokens.empty()) return false;
+
+  const verible::SyntaxTreeLeaf *first_leaf = verible::GetLeftmostLeaf(*origin);
+  if (first_leaf == nullptr) return false;
+
+  const verible::TokenInfo &first_tree_token = first_leaf->get();
+  auto ftoken_it = ftokens.begin();
+  while (ftoken_it != ftokens.end() &&
+         *(ftoken_it->token) != first_tree_token) {
+    ++ftoken_it;
+  }
+  if (ftoken_it == ftokens.begin() || ftoken_it == ftokens.end()) return false;
+  return ftoken_it->before.break_decision == verible::SpacingOptions::kMustWrap;
+}
+
 static bool IgnoreCommentsAndPreprocessingDirectives(
     const TokenPartitionTree &partition) {
   const auto &uwline = partition.Value();
@@ -159,6 +185,8 @@
   // ignore lines containing only comments
   if (TokensAreAllCommentsOrAttributes(token_range)) return true;
 
+  if (PartitionHasLeadingTokensBeforeForcedWrap(partition)) return true;
+
   // ignore partitions belonging to preprocessing directives
   return IsPreprocessorKeyword(
       verilog_tokentype(token_range.front().TokenEnum()));
@@ -199,6 +227,8 @@
     return true;
   }
 
+  if (PartitionHasLeadingTokensBeforeForcedWrap(partition)) return true;
+
   // ignore nested structs/unions
   if (verible::FindFirstSubtree(
           partition.Value().Origin(), [](const Symbol &symbol) {

verible/verilog/formatting/formatter_test.cc

diff --git a/verible/verilog/formatting/formatter_test.cc b/verible/verilog/formatting/formatter_test.cc
index 5205a01..6cffcfe 100644
--- a/verible/verilog/formatting/formatter_test.cc
+++ b/verible/verilog/formatting/formatter_test.cc
@@ -19380,6 +19380,32 @@
   }
 }
 
+// Regression for https://github.com/chipsalliance/verible/issues/2539:
+// A // comment followed by a line-continuation `\` before aligned ports must
+// not abort in align.h, and must keep the comment on its own line.
+TEST(FormatterEndToEndTest, PortListCommentWithLineContinuationDoesNotAbort) {
+  static constexpr std::string_view kInput =
+      "module m (\n"
+      "//\\\n"
+      "input a\n"
+      ",input b\n"
+      ");\n"
+      "endmodule\n";
+  FormatStyle style;
+  std::ostringstream stream;
+  const auto status = FormatVerilog(kInput, "<filename>", style, stream);
+  EXPECT_OK(status) << status.message();
+  const std::string out = stream.str();
+  // Must not glue the line-continuation onto the following port declaration.
+  EXPECT_THAT(out, testing::Not(testing::HasSubstr("//\\  input")));
+  EXPECT_THAT(out, testing::HasSubstr("//\\"));
+  EXPECT_THAT(out, testing::HasSubstr("input a"));
+  EXPECT_THAT(out, testing::HasSubstr("input b"));
+  EXPECT_THAT(out, testing::HasSubstr("endmodule"));
+  // Comment line and first port remain on separate lines.
+  EXPECT_THAT(out, testing::ContainsRegex(R"(//\\\n\s*input a)"));
+}
+
 // Regression for https://github.com/chipsalliance/verible/issues/2542:
 // Continuation EOL comments after a wrapped assign must keep a stable column
 // across re-format (convergence).