fix class

style validation

changelog

ci/release/changelogs/next.md

@@ -6,6 +6,7 @@
 
 - ELK self loops get distributed around the object instead of stacking [#1232](https://github.com/terrastruct/d2/pull/1232)
 - ELK preserves order of objects in cycles [#1235](https://github.com/terrastruct/d2/pull/1235)
+- Improper usages of `class` and `style` get error messages [#1254](https://github.com/terrastruct/d2/pull/1254)
 
 #### Bugfixes ⛑️
 

d2compiler/compile.go

@@ -197,6 +197,7 @@ func (c *compiler) compileField(obj *d2graph.Object, f *d2ir.Field) {
 		return
 	} else if f.Name == "style" {
 		if f.Map() == nil {
+			c.errorf(f.LastRef().AST(), `"style" expected to be set to a map, or contain an additional keyword like "style.opacity: 0.4"`)
 			return
 		}
 		c.compileStyle(&obj.Attributes, f.Map())
@@ -481,6 +482,10 @@ func (c *compiler) compileStyle(attrs *d2graph.Attributes, m *d2ir.Map) {
 }
 
 func (c *compiler) compileStyleField(attrs *d2graph.Attributes, f *d2ir.Field) {
+	if _, ok := d2graph.StyleKeywords[f.Name]; !ok {
+		c.errorf(f.LastRef().AST(), `invalid style keyword: "%s"`, f.Name)
+		return
+	}
 	if f.Primary() == nil {
 		return
 	}

d2compiler/compile_test.go

@@ -1678,6 +1678,24 @@ x.a.b`,
 }`,
 			expErr: `d2/testdata/d2compiler/TestCompile/no-nested-columns-class.d2:3:5: class fields cannot have children`,
 		},
+		{
+			name: "improper-class-ref",
+
+			text:   `myobj.class.style.stroke-dash: 3`,
+			expErr: `d2/testdata/d2compiler/TestCompile/improper-class-ref.d2:1:7: "class" must be the last part of the key`,
+		},
+		{
+			name: "tail-style",
+
+			text:   `myobj.style: 3`,
+			expErr: `d2/testdata/d2compiler/TestCompile/tail-style.d2:1:7: "style" expected to be set to a map, or contain an additional keyword like "style.opacity: 0.4"`,
+		},
+		{
+			name: "bad-style-nesting",
+
+			text:   `myobj.style.style.stroke-dash: 3`,
+			expErr: `d2/testdata/d2compiler/TestCompile/bad-style-nesting.d2:1:13: invalid style keyword: "style"`,
+		},
 		{
 			name: "edge_to_style",
 

d2ir/d2ir.go

@@ -671,6 +671,10 @@ func (m *Map) ensureField(i int, kp *d2ast.KeyPath, refctx *RefContext) (*Field,
 		head = strings.ToLower(head)
 	}
 
+	if head == "class" && i < len(kp.Path)-1 {
+		return nil, d2parser.Errorf(kp.Path[i].Unbox(), `"class" must be the last part of the key`)
+	}
+
 	if head == "_" {
 		return nil, d2parser.Errorf(kp.Path[i].Unbox(), `parent "_" can only be used in the beginning of paths, e.g. "_.x"`)
 	}