Expand parse_meta compiletests

tests/compile-fail/parse_meta.stderr

@@ -0,0 +1,17 @@
+error[E0277]: the trait bound `NotMacroArgs: FromMeta` is not satisfied
+ --> tests/compile-fail/parse_meta.rs:8:16
+  |
+8 |     let args = parse_meta!(args as NotMacroArgs);
+  |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `FromMeta` is not implemented for `NotMacroArgs`
+  |
+  = help: the following other types implement trait `FromMeta`:
+            ()
+            Arc<T>
+            AtomicBool
+            ExprArray
+            ExprPath
+            Flag
+            HashMap<proc_macro2::Ident, V, S>
+            HashMap<std::string::String, V, S>
+          and $N others
+  = note: this error originates in the macro `parse_meta` (in Nightly builds, run with -Z macro-backtrace for more info)

tests/compile-fail/parse_meta_invalid_receiver.rs

@@ -0,0 +1,13 @@
+extern crate proc_macro;
+use darling::parse_meta;
+use proc_macro::TokenStream;
+
+struct NotMacroArgs;
+
+pub fn invalid_receiver_type(args: TokenStream, _input: TokenStream) -> TokenStream {
+    let args = parse_meta!(args as NotMacroArgs);
+
+    unimplemented!()
+}
+
+fn main() {}

tests/compile-fail/parse_meta_invalid_receiver.stderr

@@ -0,0 +1,17 @@
+error[E0277]: the trait bound `NotMacroArgs: FromMeta` is not satisfied
+ --> tests/compile-fail/parse_meta_invalid_receiver.rs:8:16
+  |
+8 |     let args = parse_meta!(args as NotMacroArgs);
+  |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `FromMeta` is not implemented for `NotMacroArgs`
+  |
+  = help: the following other types implement trait `FromMeta`:
+            ()
+            Arc<T>
+            AtomicBool
+            ExprArray
+            ExprPath
+            Flag
+            HashMap<proc_macro2::Ident, V, S>
+            HashMap<std::string::String, V, S>
+          and $N others
+  = note: this error originates in the macro `parse_meta` (in Nightly builds, run with -Z macro-backtrace for more info)

tests/compile-success/readme_example.rs → tests/compile-fail/parse_meta_no_type.rs

@@ -11,10 +11,10 @@ struct MacroArgs {
 }
 
 pub fn your_attr(args: TokenStream, input: TokenStream) -> TokenStream {
-    let _args = parse_meta!(args as MacroArgs);
+    let args = parse_meta!(args);
     let _input = syn::parse_macro_input!(input as ItemFn);
 
-    // do things with `args`
+    println!("{:?}", args.timeout_ms);
     unimplemented!()
 }
 

tests/compile-fail/parse_meta_no_type.stderr

@@ -0,0 +1,13 @@
+error[E0282]: type annotations needed
+  --> tests/compile-fail/parse_meta_no_type.rs:14:9
+   |
+14 |     let args = parse_meta!(args);
+   |         ^^^^
+...
+17 |     println!("{:?}", args.timeout_ms);
+   |                      ---- type must be known at this point
+   |
+help: consider giving `args` an explicit type
+   |
+14 |     let args: _ = parse_meta!(args);
+   |             +++

tests/compile-pass/parse_meta.rs

@@ -0,0 +1,31 @@
+extern crate proc_macro;
+use darling::{parse_meta, FromMeta};
+use proc_macro::TokenStream;
+use syn::ItemFn;
+
+#[derive(Debug, Clone, FromMeta)]
+struct MacroArgs {
+    #[darling(default)]
+    timeout_ms: Option<u16>,
+    path: String,
+}
+
+pub fn with_explicit_type(args: TokenStream, input: TokenStream) -> TokenStream {
+    let _args = parse_meta!(args as MacroArgs);
+    let _input = syn::parse_macro_input!(input as ItemFn);
+
+    // do things with `args`
+    unimplemented!()
+}
+
+pub fn example_with_inferred_type(args: TokenStream, _input: TokenStream) -> TokenStream {
+    fn takes_macro_args(args: MacroArgs) -> Option<u16> {
+        args.timeout_ms
+    }
+
+    let _timeout = takes_macro_args(parse_meta!(args));
+
+    unimplemented!()
+}
+
+fn main() {}

tests/compiletests.rs

@@ -5,7 +5,7 @@
 fn compile_test() {
     let t = trybuild::TestCases::new();
     t.compile_fail("tests/compile-fail/*.rs");
-    t.pass("tests/compile-success/*.rs");
+    t.pass("tests/compile-pass/*.rs");
 }
 
 #[rustversion::not(stable(1.65))]