Only consider comments inside a span if they are fully inside the spa…

…n; previously they were considered "in the span" if their line number was in the span.

This was causing issues when formatting short blocks with comments, especially in tuples:

`if bar > u32:0 { u1:1} else {1:0} // this comment will be repeated`

which was erroneously formatted to:

```
    if bar > u32:0 {
        u1:1  // this comment will be repeated
    } else {
        u1:0  // this comment will be repeated
    } // this comment will be repeated
```

Fixes #1678

PiperOrigin-RevId: 713388090

xls/dslx/fmt/ast_fmt.cc

@@ -1276,15 +1276,10 @@ DocRef FmtTupleWithoutComments(const XlsTuple& n, Comments& comments,
              });
 }
 
-bool CommentsWithin(const Span& span, Comments& comments) {
-  std::vector<const CommentData*> items = comments.GetComments(span);
-  return !items.empty();
-}
-
 DocRef FmtTuple(const XlsTuple& n, Comments& comments, DocArena& arena) {
   Span tuple_span = n.span();
   // Detect if there are any comments in the span of the tuple.
-  bool any_comments = CommentsWithin(tuple_span, comments);
+  bool any_comments = comments.HasComments(tuple_span);
 
   if (!any_comments) {
     // Do it the old way.
@@ -1314,6 +1309,8 @@ DocRef FmtTuple(const XlsTuple& n, Comments& comments, DocArena& arena) {
         pieces.push_back(arena.comma());
         pieces.push_back(arena.space());
       }
+      // TODO: davidplass - if the previous comment is not on the same line as
+      // the previous element, insert a hard line before the comment.
       pieces.push_back(previous_comments.value());
       pieces.push_back(arena.hard_line());
     } else if (!first_element) {
@@ -1503,7 +1500,7 @@ DocRef Fmt(const StructInstance& n, Comments& comments, DocArena& arena) {
   // If there are comments within the span, we must go to break mode, because
   // newlines.
   DocRef on_break = FmtBreakRest(n, comments, arena);
-  if (CommentsWithin(n.span(), comments)) {
+  if (comments.HasComments(n.span())) {
     return arena.MakeConcat(leader, on_break);
   }
 

xls/dslx/fmt/ast_fmt_test.cc

@@ -3343,5 +3343,48 @@ struct Foo { a: u1, b: u1 }
 )");
 }
 
+TEST_F(ModuleFmtTest, TupleWithComment_GH_1678) {
+  DoFmt(R"(fn foo(bar: u32) {
+    let some_data_to_make_single_update_per_line = u32:0xabcdef;
+    (
+        bit_slice_update(
+            some_data_to_make_single_update_per_line, 1,
+            if bar > u32:0xdeadbeef { u1:1 } else { u1:0 }), // this is yet another comment
+    )
+}
+)");
+}
+
+TEST_F(ModuleFmtTest, TupleWithMultipleComments_GH_1678) {
+  DoFmt(R"(fn foo(bar: u32) {
+    let some_data_to_make_single_update_per_line = u32:0xabcdef;
+    (
+        // TODO: davidplass - if the previous comment is not on the same line as
+        // the previous element, insert a hard line before the comment.
+        bit_slice_update(some_data_to_make_single_update_per_line, 0, u1:1),
+        // This is an important comment
+        bit_slice_update(
+            some_data_to_make_single_update_per_line, 1,
+            if bar > u32:0xdeadbeef { u1:1 } else { u1:0 }), // this is yet another comment
+        bit_slice_update(some_data_to_make_single_update_per_line, 2, u1:1)
+    )
+}
+)",
+        R"(fn foo(bar: u32) {
+    let some_data_to_make_single_update_per_line = u32:0xabcdef;
+    (
+        // TODO: davidplass - if the previous comment is not on the same line as
+        // the previous element, insert a hard line before the comment.
+        bit_slice_update(some_data_to_make_single_update_per_line, 0, u1:1), // This is an important
+        // comment
+        bit_slice_update(
+            some_data_to_make_single_update_per_line, 1,
+            if bar > u32:0xdeadbeef { u1:1 } else { u1:0 }), // this is yet another comment
+        bit_slice_update(some_data_to_make_single_update_per_line, 2, u1:1)
+    )
+}
+)");
+}
+
 }  // namespace
 }  // namespace xls::dslx

xls/dslx/fmt/comments.cc

@@ -46,16 +46,6 @@ namespace xls::dslx {
   return Comments{std::move(line_to_comment), last_data_limit};
 }
 
-bool Comments::HasComments(const Span& in_span) const {
-  for (int64_t i = in_span.start().lineno(); i <= in_span.limit().lineno();
-       ++i) {
-    if (auto it = line_to_comment_.find(i); it != line_to_comment_.end()) {
-      return true;
-    }
-  }
-  return false;
-}
-
 static bool InRange(const Span& node_span, const CommentData& comment) {
   // For multiline comments, consider in range if the comment start is within
   // the node span. Since all comments end on the line below the comment,
@@ -66,6 +56,19 @@ static bool InRange(const Span& node_span, const CommentData& comment) {
   return overlapping_multiline || node_span.Contains(comment.span);
 }
 
+bool Comments::HasComments(const Span& in_span) const {
+  for (int64_t i = in_span.start().lineno(); i <= in_span.limit().lineno();
+       ++i) {
+    if (auto it = line_to_comment_.find(i); it != line_to_comment_.end()) {
+      const CommentData& cd = it->second;
+      if (InRange(in_span, cd)) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
 std::vector<const CommentData*> Comments::GetComments(
     const Span& node_span) const {
   // Implementation note: this will typically be a single access (as most things