From 3ff40241ee6fe129267401f306fed1bd34fdc04d Mon Sep 17 00:00:00 2001
From: Chris Mounce <christophermounce@gmail.com>
Date: Sat, 5 Jul 2025 23:49:57 -0700
Subject: [PATCH] Add more error messages for local/anonymous labels

---
 src/labels/parse.rs                           | 22 +++++++++
 src/labels/process.rs                         | 13 +++--
 ...m__labels__process__test__diagnostics.snap | 47 +++++++++++++++++++
 tests/labels/diagnostics.txt                  | 13 +++++
 4 files changed, 92 insertions(+), 3 deletions(-)

diff --git a/src/labels/parse.rs b/src/labels/parse.rs
index 190151e..a0cae52 100644
--- a/src/labels/parse.rs
+++ b/src/labels/parse.rs
@@ -52,6 +52,28 @@ pub fn parse_stat_labels(stat: &Stat, ctx: &Context) -> ParsedStat {
             Tag::Reference => {
                 let label = cap.children().find(|c| c.kind() == Tag::Label).unwrap();
                 label_captures.push((Tag::Reference, label));
+
+                // Detect invalid recipients.
+                // This should probably happen later in processing, but
+                // we'd need an AST that can track spans for message recipients.
+                let mut recipient = None;
+                let (mut anon, mut local) = (false, false);
+                for child in cap.walk_children() {
+                    match child.kind() {
+                        Tag::Anon => anon = true,
+                        Tag::Local => local = true,
+                        Tag::Recipient => recipient = Some(child),
+                        _ => {}
+                    }
+                }
+                if let Some(recipient) = recipient {
+                    let ctx = ctx.with_span(recipient.span());
+                    if anon {
+                        ctx.error("message targets not allowed for anonymous labels");
+                    } else if local {
+                        ctx.error("message targets not supported for local labels");
+                    }
+                }
             }
             _ => {}
         }
diff --git a/src/labels/process.rs b/src/labels/process.rs
index 6cd07c8..1fe866f 100644
--- a/src/labels/process.rs
+++ b/src/labels/process.rs
@@ -20,7 +20,7 @@ pub fn process_labels(board: &Board, ctx: &Context) -> Board {
         .collect();
     let mut registry = Registry::new();
 
-    resolve_local_labels(&mut stats);
+    resolve_local_labels(&mut stats, ctx);
     assign_named_labels(&mut stats, &mut registry);
 
     // Assign names to anonymous labels
@@ -47,8 +47,10 @@ pub fn process_labels(board: &Board, ctx: &Context) -> Board {
 }
 
 /// Resolve ".local" labels to "name.local" form.
-fn resolve_local_labels(stats: &mut [ParsedStat]) {
-    for stat in stats.iter_mut() {
+fn resolve_local_labels(stats: &mut [ParsedStat], ctx: &Context) {
+    for (i, stat) in stats.iter_mut().enumerate() {
+        let ctx = ctx.with_stat(i);
+
         // Helper: Generate unique section strings like "touch$0"
         let mut i = 0;
         let mut make_section_id = |label_name: &str| -> CompactString {
@@ -89,6 +91,11 @@ fn resolve_local_labels(stats: &mut [ParsedStat]) {
                             namespace_to_section
                                 .insert(label.namespace.clone(), make_section_id(&label.name));
                         }
+                    } else {
+                        // User specified both a section name and a local name ("name.local").
+                        // This isn't allowed because of issues around resolving the section ID.
+                        ctx.with_span(label.span.clone())
+                            .error("local labels with section names not supported");
                     }
                 }
                 _ => {}
diff --git a/src/labels/snapshots/zasm__labels__process__test__diagnostics.snap b/src/labels/snapshots/zasm__labels__process__test__diagnostics.snap
index 557308b..4af7276 100644
--- a/src/labels/snapshots/zasm__labels__process__test__diagnostics.snap
+++ b/src/labels/snapshots/zasm__labels__process__test__diagnostics.snap
@@ -44,3 +44,50 @@ error: backward reference needs an anonymous label
  2 | #send @f
  3 | #send @b
    |       ^^
+
+error: message targets not allowed for anonymous labels
+ => test.zzt -> Title screen -> @Disallowed targets (1,1) -> line 3:2
+   |
+ 1 | @Disallowed targets
+ 2 | :@
+ 3 | #self:@b
+   |  ^^^^
+ 4 | #others:@f
+ 5 | #all:.local
+ 6 | :@
+   |
+
+error: message targets not allowed for anonymous labels
+ => test.zzt -> Title screen -> @Disallowed targets (1,1) -> line 4:2
+   |
+ 1 | @Disallowed targets
+ 2 | :@
+ 3 | #self:@b
+ 4 | #others:@f
+   |  ^^^^^^
+ 5 | #all:.local
+ 6 | :@
+ 7 | :.local
+   |
+
+error: message targets not supported for local labels
+ => test.zzt -> Title screen -> @Disallowed targets (1,1) -> line 5:2
+   |
+ 2 | :@
+ 3 | #self:@b
+ 4 | #others:@f
+ 5 | #all:.local
+   |  ^^^
+ 6 | :@
+ 7 | :.local
+   |
+
+error: local labels with section names not supported
+ => test.zzt -> Title screen -> @Locals with section names (1,1) -> line 3:2
+   |
+ 1 | @Locals with section names
+ 2 | :touch
+ 3 | #touch.skip
+   |  ^^^^^^^^^^
+ 4 | :.skip
+   |
diff --git a/tests/labels/diagnostics.txt b/tests/labels/diagnostics.txt
index 6899f40..9038b8b 100644
--- a/tests/labels/diagnostics.txt
+++ b/tests/labels/diagnostics.txt
@@ -14,3 +14,16 @@
 @Errors in sorted order
 #send @f
 #send @b
+---
+@Disallowed targets
+:@
+#self:@b
+#others:@f
+#all:.local
+:@
+:.local
+---
+@Locals with section names
+:touch
+#touch.skip
+:.skip