fix: Recursive parsing of attributes

The `test_parse` macro is changed to recursively parse attributes,
filtering out the `#[ignore]` macro. This should also make it fairly
trivial to add additional macros, such as `#[should_ignore]`.

There is a fair amount of complexity added to the macro with this
change, but on the other hand, it also succeeds in generating only the
necessary code. You win some, you lose some.

Author: skogseth

crates/libtest2/src/macros.rs

@@ -14,22 +14,58 @@ macro_rules! _main_parse {
 }
 
 #[macro_export]
-macro_rules! _parse_ignore {
-    (ignore) => {
-        ::std::option::Option::<&'static str>::None
+#[allow(clippy::crate_in_macro_def)] // accessing item defined by `_main_parse`/`_parse_ignore`, and recursively calling the macro itself
+macro_rules! _test_parse {
+    // Entry point
+    (#[test] $(#[$($attr:tt)+])* fn $name:ident $($item:tt)*) => {
+        $crate::_private::test_parse!(continue:
+            name=$name
+            body=[$($item)*]
+            attrs=[$(#[$($attr)+])*]
+        );
+    };
+
+    // Recursively handle attributes:
+
+    // Edge condition (no more attributes to parse)
+    (continue: name=$name:ident body=[$($item:tt)*] attrs=[] $(ignore=$ignore:tt)?) => {
+        $crate::_private::test_parse!(break:
+            name=$name
+            body=[$($item)*]
+            $(ignore=$ignore)?
+        );
     };
-    (ignore = $reason:expr) => {
-        ::std::option::Option::<&'static str>::Some($reason)
+    // Process `#[ignore]`/`#[ignore = ".."]` (NOTE: This will only match if an ignore macro has not already been parsed)
+    (continue: name=$name:ident body=[$($item:tt)*] attrs=[#[ignore $(= $reason:literal)?] $(#[$($attr:tt)+])*]) => {
+        $crate::_private::test_parse!(continue:
+            name=$name
+            body=[$($item)*]
+            attrs=[$(#[$($attr)*])*]
+            ignore=[$($reason)?]
+        );
     };
-    ($($attr:tt)*) => {
-        compile_error!(concat!("unknown attribute '", stringify!($($attr)*), "'"));
+    // Ignore subsequent calls to `#[ignore]`/`#[ignore = ".."]`
+    (continue: name=$name:ident body=[$($item:tt)*] attrs=[#[ignore $(= $reason:literal)?] $(#[$($attr:tt)+])*] ignore=$ignore:tt) => {
+        $crate::_private::test_parse!(continue:
+            name=$name
+            body=[$($item)*]
+            attrs=[$(#[$($attr)*])*]
+            ignore=$ignore
+        );
+    };
+    // Emit error on unknown attributes (but continue parsing)
+    (continue: name=$name:ident body=[$($item:tt)*] attrs=[#[$($unknown_attr:tt)+] $(#[$($attr:tt)+])*] $(ignore=$ignore:tt)?) => {
+        compile_error!(concat!("unknown attribute '", stringify!($($unknown_attr)+), "'"));
+        $crate::_private::test_parse!(continue:
+            name=$name
+            body=[$($item)*]
+            attrs=[$(#[$($attr)*])*]
+            $(ignore=$ignore)?
+        );
     };
-}
 
-#[macro_export]
-#[allow(clippy::crate_in_macro_def)] // accessing item defined by `_main_parse`
-macro_rules! _test_parse {
-    (#[test] $(#[$($attr:tt)*])* fn $name:ident $($item:tt)*) => {
+    // End result
+    (break: name=$name:ident body=[$($item:tt)*] $(ignore=$ignore:tt)?) => {
         #[allow(non_camel_case_types)]
         struct $name;
 
@@ -52,12 +88,7 @@ macro_rules! _test_parse {
             fn run(&self, context: &$crate::TestContext) -> $crate::RunResult {
                 fn run $($item)*
 
-                $(
-                    match $crate::_private::parse_ignore!($($attr)*) {
-                        ::std::option::Option::None => context.ignore()?,
-                        ::std::option::Option::Some(reason) => context.ignore_for(reason)?,
-                    }
-                )*
+                $crate::_private::parse_ignore!(context, $($ignore)?);
 
                 use $crate::IntoRunResult;
                 let result = run(context);
@@ -66,3 +97,14 @@ macro_rules! _test_parse {
         }
     };
 }
+
+#[macro_export]
+macro_rules! _parse_ignore {
+    ($context:expr, [$reason:literal] $(,)?) => {
+        $context.ignore_for($reason)?
+    };
+    ($context:expr, [] $(,)?) => {
+        $context.ignore()?
+    };
+    ($context:expr $(,)?) => {};
+}