Tag with no args in error msgs (#471)

compiler/constrain/src/expr.rs

@@ -758,7 +758,10 @@ pub fn constrain_expr(
                     Box::new(Type::Variable(*ext_var)),
                 ),
                 expected.clone(),
-                Category::TagApply(name.clone()),
+                Category::TagApply {
+                    tag_name: name.clone(),
+                    args_count: arguments.len(),
+                },
                 region,
             );
             let ast_con = Eq(

compiler/constrain/src/uniq.rs

@@ -620,13 +620,19 @@ pub fn constrain_expr(
             let union_con = Eq(
                 union_type,
                 expected.clone(),
-                Category::TagApply(name.clone()),
+                Category::TagApply {
+                    tag_name: name.clone(),
+                    args_count: arguments.len(),
+                },
                 region,
             );
             let ast_con = Eq(
                 Type::Variable(*variant_var),
                 expected,
-                Category::TagApply(name.clone()),
+                Category::TagApply {
+                    tag_name: name.clone(),
+                    args_count: arguments.len(),
+                },
                 region,
             );
 

compiler/reporting/src/error/type.rs

@@ -882,12 +882,39 @@ fn add_category<'b>(
 
         Lambda => alloc.concat(vec![this_is, alloc.text(" an anonymous function of type:")]),
 
-        TagApply(TagName::Global(name)) => alloc.concat(vec![
+        TagApply {
+            tag_name: TagName::Global(name),
+            args_count: 0,
+        } => alloc.concat(vec![
+            alloc.text("This "),
+            alloc.global_tag_name(name.to_owned()),
+            if name.as_str() == "True" || name.as_str() == "False" {
+                alloc.text(" boolean has the type:")
+            } else {
+                alloc.text(" global tag has the type:")
+            },
+        ]),
+        TagApply {
+            tag_name: TagName::Private(name),
+            args_count: 0,
+        } => alloc.concat(vec![
+            alloc.text("This "),
+            alloc.private_tag_name(*name),
+            alloc.text(" private tag has the type:"),
+        ]),
+
+        TagApply {
+            tag_name: TagName::Global(name),
+            args_count: _,
+        } => alloc.concat(vec![
             alloc.text("This "),
             alloc.global_tag_name(name.to_owned()),
             alloc.text(" global tag application has the type:"),
         ]),
-        TagApply(TagName::Private(name)) => alloc.concat(vec![
+        TagApply {
+            tag_name: TagName::Private(name),
+            args_count: _,
+        } => alloc.concat(vec![
             alloc.text("This "),
             alloc.private_tag_name(*name),
             alloc.text(" private tag application has the type:"),

compiler/types/src/types.rs

@@ -927,7 +927,10 @@ pub enum Category {
     Lookup(Symbol),
     CallResult(Option<Symbol>),
     LowLevelOpResult(LowLevel),
-    TagApply(TagName),
+    TagApply {
+        tag_name: TagName,
+        args_count: usize,
+    },
     Lambda,
     Uniqueness,
     StrInterpolation,