compiler: keep class field and method types that match the name

ci/release/changelogs/next.md

@@ -51,6 +51,10 @@
   - Limit wildcard edge connections and selectors to bounded expansion work,
     returning a clear error before excessive fanout consumes resources.
     [#2926](https://github.com/d2lang/d2/pull/2926)
+  - Keep `sql_table` column types that match the column name, such as
+    `date: date`, instead of rendering an empty type. [#2950](https://github.com/d2lang/d2/pull/2950)
+  - Keep `class` field types and method return types that match the name, such
+    as `date: date`, instead of dropping them. [#2952](https://github.com/d2lang/d2/pull/2952)
 - decoding and assets:
   - Cap decompressed URL-encoded D2 input at 16 MiB. [#2902](https://github.com/d2lang/d2/pull/2902)
   - Bound image references, locators, fetched and decoded bytes, cached data, and

d2compiler/compile.go

@@ -421,6 +421,7 @@ type compiler struct {
 	err             *d2parser.ParseError
 	activeClassMaps map[*d2ir.Map]struct{}
 	classMapsByRoot map[*d2ir.Map]map[string]*d2ir.Map
+	explicitLabels  map[*d2graph.Attributes]struct{}
 	ctx             context.Context
 	fatalErr        error
 }
@@ -793,6 +794,15 @@ func (c *compiler) compileLabel(attrs *d2graph.Attributes, f d2ir.Node) {
 		attrs.Label.Value = scalar.ScalarString()
 	}
 	attrs.Label.MapKey = f.LastPrimaryKey()
+	if c.explicitLabels == nil {
+		c.explicitLabels = make(map[*d2graph.Attributes]struct{})
+	}
+	c.explicitLabels[attrs] = struct{}{}
+}
+
+func (c *compiler) hasExplicitLabel(attrs *d2graph.Attributes) bool {
+	_, ok := c.explicitLabels[attrs]
+	return ok
 }
 
 func (c *compiler) compilePosition(attrs *d2graph.Attributes, f *d2ir.Field) {
@@ -1407,9 +1417,10 @@ func (c *compiler) compileClass(obj *d2graph.Object) {
 			}
 		}
 
+		// A field or method without an explicit label defaults it to its ID, which is not a type.
 		if !strings.Contains(f.IDVal, "(") {
 			typ := f.Label.Value
-			if typ == f.IDVal {
+			if !c.hasExplicitLabel(&f.Attributes) && typ == f.IDVal {
 				typ = ""
 			}
 			underline := f.Attributes.Style.Underline != nil && f.Attributes.Style.Underline.Value == "true"
@@ -1420,10 +1431,8 @@ func (c *compiler) compileClass(obj *d2graph.Object) {
 				Underline:  underline,
 			})
 		} else {
-			// TODO: Not great, AST should easily allow specifying alternate primary field
-			// as an explicit label should change the name.
 			returnType := f.Label.Value
-			if returnType == f.IDVal {
+			if !c.hasExplicitLabel(&f.Attributes) && returnType == f.IDVal {
 				returnType = "void"
 			}
 			underline := f.Attributes.Style.Underline != nil && f.Attributes.Style.Underline.Value == "true"
@@ -1464,9 +1473,8 @@ func (c *compiler) compileSQLTable(obj *d2graph.Object) {
 			return
 		}
 		typ := col.Label.Value
-		if typ == col.IDVal {
-			// Not great, AST should easily allow specifying alternate primary field
-			// as an explicit label should change the name.
+		// A column without an explicit label defaults it to its ID, which is not a type.
+		if !c.hasExplicitLabel(&col.Attributes) && typ == col.IDVal {
 			typ = ""
 		}
 		d2Col := d2target.SQLColumn{

d2compiler/compile_test.go

@@ -2857,6 +2857,47 @@ x.y -> a.b: {
 				assert.String(t, `Is()`, g.Objects[0].SQLTable.Columns[1].Name.Label)
 			},
 		},
+		{
+			name: "sql_column_type_matches_name",
+
+			text: `time: {
+  shape: sql_table
+  id
+  created {constraint: primary_key}
+  date: date
+  key: key
+  key {constraint: unique}
+}
+`,
+			assertions: func(t *testing.T, g *d2graph.Graph) {
+				cols := g.Objects[0].SQLTable.Columns
+				assert.String(t, ``, cols[0].Type.Label)
+				assert.String(t, ``, cols[1].Type.Label)
+				assert.String(t, `date`, cols[2].Type.Label)
+				assert.String(t, `key`, cols[3].Type.Label)
+			},
+		},
+		{
+			name: "class_field_type_matches_name",
+
+			text: `Event: {
+  shape: class
+  id
+  date: date
+  +status: status
+  save()
+  now(): now()
+}
+`,
+			assertions: func(t *testing.T, g *d2graph.Graph) {
+				class := g.Objects[0].Class
+				assert.String(t, ``, class.Fields[0].Type)
+				assert.String(t, `date`, class.Fields[1].Type)
+				assert.String(t, `status`, class.Fields[2].Type)
+				assert.String(t, `void`, class.Methods[0].Return)
+				assert.String(t, `now()`, class.Methods[1].Return)
+			},
+		},
 		{
 			name: "nested_sql",