feat: Restrict defs (#138)

Author: zharinov

crates/plotnik-lib/src/diagnostics/message.rs

@@ -74,7 +74,7 @@ pub enum DiagnosticKind {
     InvalidChildType,
 
     // Often consequences of earlier errors
-    UnnamedDefNotLast,
+    UnnamedDef,
 }
 
 impl DiagnosticKind {
@@ -119,7 +119,7 @@ impl DiagnosticKind {
     /// Consequence errors - often caused by earlier parse errors.
     /// These get suppressed when any root-cause or structural error exists.
     pub fn is_consequence_error(&self) -> bool {
-        matches!(self, Self::UnnamedDefNotLast)
+        matches!(self, Self::UnnamedDef)
     }
 
     /// Base message for this diagnostic kind, used when no custom message is provided.
@@ -189,7 +189,7 @@ impl DiagnosticKind {
             Self::InvalidChildType => "node type not valid as child",
 
             // Structural
-            Self::UnnamedDefNotLast => "only the last definition can be unnamed",
+            Self::UnnamedDef => "definitions must be named",
         }
     }
 
@@ -229,8 +229,8 @@ impl DiagnosticKind {
                 "type annotations use `::`, not `:` — {}".to_string()
             }
 
-            // Named def ordering
-            Self::UnnamedDefNotLast => "only the last definition can be unnamed — {}".to_string(),
+            // Named def
+            Self::UnnamedDef => "definitions must be named — {}".to_string(),
 
             // Standard pattern: fallback + context
             _ => format!("{}; {{}}", self.fallback_message()),

crates/plotnik-lib/src/diagnostics/mod.rs

@@ -85,7 +85,7 @@ impl Diagnostics {
     /// 1. Containment: when error A's suppression_range contains error B's display range,
     ///    and A has higher priority, suppress B (only for structural errors)
     /// 2. Same position: when spans start at the same position, root-cause errors suppress structural ones
-    /// 3. Consequence errors (UnnamedDefNotLast) suppressed when any other error exists
+    /// 3. Consequence errors (UnnamedDef) suppressed when any other error exists
     /// 4. Adjacent: when error A ends exactly where error B starts, A suppresses B
     pub(crate) fn filtered(&self) -> Vec<DiagnosticMessage> {
         if self.messages.is_empty() {

crates/plotnik-lib/src/diagnostics/tests.rs

@@ -271,23 +271,23 @@ fn diagnostic_kind_default_severity() {
         Severity::Error
     );
     assert_eq!(
-        DiagnosticKind::UnnamedDefNotLast.default_severity(),
+        DiagnosticKind::UnnamedDef.default_severity(),
         Severity::Error
     );
 }
 
 #[test]
 fn diagnostic_kind_suppression_order() {
     // Higher priority (earlier in enum) suppresses lower priority (later in enum)
-    assert!(DiagnosticKind::UnclosedTree.suppresses(&DiagnosticKind::UnnamedDefNotLast));
+    assert!(DiagnosticKind::UnclosedTree.suppresses(&DiagnosticKind::UnnamedDef));
     assert!(DiagnosticKind::UnclosedTree.suppresses(&DiagnosticKind::UndefinedReference));
-    assert!(DiagnosticKind::ExpectedExpression.suppresses(&DiagnosticKind::UnnamedDefNotLast));
+    assert!(DiagnosticKind::ExpectedExpression.suppresses(&DiagnosticKind::UnnamedDef));
 
     // Same kind doesn't suppress itself
     assert!(!DiagnosticKind::UnclosedTree.suppresses(&DiagnosticKind::UnclosedTree));
 
     // Lower priority doesn't suppress higher priority
-    assert!(!DiagnosticKind::UnnamedDefNotLast.suppresses(&DiagnosticKind::UnclosedTree));
+    assert!(!DiagnosticKind::UnnamedDef.suppresses(&DiagnosticKind::UnclosedTree));
 }
 
 #[test]
@@ -364,7 +364,7 @@ fn filtered_no_suppression_disjoint_spans() {
 #[test]
 fn filtered_suppresses_lower_priority_contained() {
     let mut diagnostics = Diagnostics::new();
-    // Higher priority error (UnclosedTree) contains lower priority (UnnamedDefNotLast)
+    // Higher priority error (UnclosedTree) contains lower priority (UnnamedDef)
     diagnostics
         .report(
             DiagnosticKind::UnclosedTree,
@@ -373,7 +373,7 @@ fn filtered_suppresses_lower_priority_contained() {
         .emit();
     diagnostics
         .report(
-            DiagnosticKind::UnnamedDefNotLast,
+            DiagnosticKind::UnnamedDef,
             TextRange::new(5.into(), 15.into()),
         )
         .emit();
@@ -386,10 +386,10 @@ fn filtered_suppresses_lower_priority_contained() {
 #[test]
 fn filtered_consequence_suppressed_by_structural() {
     let mut diagnostics = Diagnostics::new();
-    // Consequence error (UnnamedDefNotLast) suppressed when structural error (UnclosedTree) exists
+    // Consequence error (UnnamedDef) suppressed when structural error (UnclosedTree) exists
     diagnostics
         .report(
-            DiagnosticKind::UnnamedDefNotLast,
+            DiagnosticKind::UnnamedDef,
             TextRange::new(0.into(), 20.into()),
         )
         .emit();
@@ -418,7 +418,7 @@ fn filtered_same_span_higher_priority_wins() {
         .emit();
     diagnostics
         .report(
-            DiagnosticKind::UnnamedDefNotLast,
+            DiagnosticKind::UnnamedDef,
             TextRange::new(0.into(), 10.into()),
         )
         .emit();
@@ -448,7 +448,7 @@ fn render_filtered() {
         .emit();
     diagnostics
         .report(
-            DiagnosticKind::UnnamedDefNotLast,
+            DiagnosticKind::UnnamedDef,
             TextRange::new(5.into(), 15.into()),
         )
         .message("unnamed def")