Tested and improved validation of #[property] attribute arguments.

tests/build/property_macro/fail/incorredt_attr_args.rs

@@ -0,0 +1,23 @@
+use zero_ui::core::{property, UiNode};
+
+#[property(context, unknown: true)]
+fn unknown_arg(child: impl UiNode, input: bool) -> impl UiNode {
+    child
+}
+
+#[property(context, allowed_in_when: "false")]
+fn invalid_allowed_in_when_value(child: impl UiNode, input: bool) -> impl UiNode {
+    child
+}
+
+#[property(context, allowed_in_when)]
+fn missing_allowed_in_when_value_1(child: impl UiNode, input: bool) -> impl UiNode {
+    child
+}
+
+#[property(context, allowed_in_when: )]
+fn missing_allowed_in_when_value_2(child: impl UiNode, input: bool) -> impl UiNode {
+    child
+}
+
+fn main() {}

tests/build/property_macro/pass/attr_args.rs

@@ -0,0 +1,27 @@
+use zero_ui::core::{property, UiNode};
+
+#[property(context)]
+fn trailing_comma_1(child: impl UiNode, input: bool) -> impl UiNode {
+    let _ = input;
+    child
+}
+
+#[property(context, allowed_in_when: true)]
+fn allowed_in_when(child: impl UiNode, input: bool) -> impl UiNode {
+    let _ = input;
+    child
+}
+
+#[property(context, allowed_in_when: false)]
+fn not_allowed_in_when(child: impl UiNode, input: bool) -> impl UiNode {
+    let _ = input;
+    child
+}
+
+#[property(context, allowed_in_when: false,)]
+fn trailing_comma_2(child: impl UiNode, input: bool) -> impl UiNode {
+    let _ = input;
+    child
+}
+
+fn main() {}

zero-ui-proc-macros/src/property.rs

@@ -27,7 +27,7 @@ pub use input::keyword;
 pub use input::Priority;
 
 mod input {
-    use syn::{parse::*, *};
+    use syn::{parse::*, spanned::Spanned, *};
 
     pub mod keyword {
         syn::custom_keyword!(context);
@@ -51,8 +51,21 @@ mod input {
             Ok(MacroArgs {
                 priority: input.parse()?,
                 allowed_in_when: {
-                    if input.peek(Token![,]) {
-                        Some((input.parse()?, input.parse()?, input.parse()?, input.parse()?))
+                    if input.peek(Token![,]) && input.peek2(keyword::allowed_in_when) {
+                        let comma = input.parse().unwrap();
+                        let allowed_in_when = input.parse::<keyword::allowed_in_when>().unwrap();
+
+                        if input.is_empty() {
+                            return Err(syn::Error::new(allowed_in_when.span(), "expected `allowed_in_when : <bool>`"));
+                        }
+                        let colon = input.parse::<Token![:]>()?;
+
+                        if input.is_empty() {
+                            return Err(syn::Error::new(colon.span(), "expected `: <bool>`"));
+                        }
+                        let bool_ = input.parse()?;
+
+                        Some((comma, allowed_in_when, colon, bool_))
                     } else {
                         None
                     }