Small tweak to printer to handle indent if there is //~ on the first line

Lines with "//~ ..." should be considered a "first line" like non-"//~" lines, to avoid overly indenting when in raw strings.

PiperOrigin-RevId: 704689179

src/google/protobuf/descriptor.pb.cc

@@ -12791,7 +12791,7 @@ void UninterpretedOption_NamePart::InternalSwap(UninterpretedOption_NamePart* PR
   _internal_metadata_.InternalSwap(&other->_internal_metadata_);
   swap(_impl_._has_bits_[0], other->_impl_._has_bits_[0]);
   ::_pbi::ArenaStringPtr::InternalSwap(&_impl_.name_part_, &other->_impl_.name_part_, arena);
-        swap(_impl_.is_extension_, other->_impl_.is_extension_);
+  swap(_impl_.is_extension_, other->_impl_.is_extension_);
 }
 
 ::google::protobuf::Metadata UninterpretedOption_NamePart::GetMetadata() const {

src/google/protobuf/io/printer.cc

@@ -160,6 +160,9 @@ Printer::Format Printer::TokenizeFormat(absl::string_view format_string,
       if (comment_index != absl::string_view::npos) {
         line_text = line_text.substr(0, comment_index);
         if (absl::StripLeadingAsciiWhitespace(line_text).empty()) {
+          // If the first line is part of an ignored comment, consider that a
+          // first line as well.
+          is_first = false;
           continue;
         }
       }

src/google/protobuf/io/printer_unittest.cc

@@ -713,6 +713,24 @@ TEST_F(PrinterTest, EmitWithIndent) {
             "  };\n");
 }
 
+TEST_F(PrinterTest, EmitWithIndentAndIgnoredCommentOnFirstLine) {
+  {
+    Printer printer(output());
+    auto v = printer.WithIndent();
+    printer.Emit({{"f1", "x"}, {"f2", "y"}, {"f3", "z"}}, R"cc(
+      //~ First line comment.
+      class Foo {
+        int $f1$, $f2$, $f3$;
+      };
+    )cc");
+  }
+
+  EXPECT_EQ(written(),
+            "  class Foo {\n"
+            "    int x, y, z;\n"
+            "  };\n");
+}
+
 TEST_F(PrinterTest, EmitWithPreprocessor) {
   {
     Printer printer(output());