Reorganize rust crates into a flat crates directory, simplify some CI steps (#4496)

* Move all rust crates (except lib) into crates dir, w/o nesting

* Remove stale path from .gitattributes

* Rename lib.rs files for easier navigation

* Rename mod.rs file for easier navigation

* Fix emscripten-version path

* Fix fixtures dir paths

* Use the default rustfmt settings

* Don't use nightly on CI

crates/cli/src/tests/proc_macro/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "tree-sitter-tests-proc-macro"
+version = "0.0.0"
+edition.workspace = true
+rust-version.workspace = true
+publish = false
+
+[lints]
+workspace = true
+
+[lib]
+proc-macro = true
+
+[dependencies]
+proc-macro2 = "1.0.93"
+quote = "1.0.38"
+rand = "0.8.5"
+syn = { version = "2.0.96", features = ["full"] }

crates/cli/src/tests/proc_macro/src/lib.rs

@@ -0,0 +1,135 @@
+use proc_macro::TokenStream;
+use proc_macro2::Span;
+use quote::quote;
+use syn::{
+    parse::{Parse, ParseStream},
+    parse_macro_input, Error, Expr, Ident, ItemFn, LitInt, Token,
+};
+
+#[proc_macro_attribute]
+pub fn retry(args: TokenStream, input: TokenStream) -> TokenStream {
+    let count = parse_macro_input!(args as LitInt);
+    let input = parse_macro_input!(input as ItemFn);
+    let attrs = &input.attrs;
+    let name = &input.sig.ident;
+
+    TokenStream::from(quote! {
+        #(#attrs),*
+        fn #name() {
+            #input
+
+            for i in 0..=#count {
+                let result = std::panic::catch_unwind(|| {
+                    #name();
+                });
+
+                if result.is_ok() {
+                    return;
+                }
+
+                if i == #count {
+                    std::panic::resume_unwind(result.unwrap_err());
+                }
+            }
+        }
+    })
+}
+
+#[proc_macro_attribute]
+pub fn test_with_seed(args: TokenStream, input: TokenStream) -> TokenStream {
+    struct Args {
+        retry: LitInt,
+        seed: Expr,
+        seed_fn: Option<Ident>,
+    }
+
+    impl Parse for Args {
+        fn parse(input: ParseStream) -> syn::Result<Self> {
+            let mut retry = None;
+            let mut seed = None;
+            let mut seed_fn = None;
+
+            while !input.is_empty() {
+                let name = input.parse::<Ident>()?;
+                match name.to_string().as_str() {
+                    "retry" => {
+                        input.parse::<Token![=]>()?;
+                        retry.replace(input.parse()?);
+                    }
+                    "seed" => {
+                        input.parse::<Token![=]>()?;
+                        seed.replace(input.parse()?);
+                    }
+                    "seed_fn" => {
+                        input.parse::<Token![=]>()?;
+                        seed_fn.replace(input.parse()?);
+                    }
+                    x => {
+                        return Err(Error::new(
+                            name.span(),
+                            format!("Unsupported parameter `{x}`"),
+                        ))
+                    }
+                }
+
+                if !input.is_empty() {
+                    input.parse::<Token![,]>()?;
+                }
+            }
+
+            if retry.is_none() {
+                retry.replace(LitInt::new("0", Span::mixed_site()));
+            }
+
+            Ok(Self {
+                retry: retry.expect("`retry` parameter is required"),
+                seed: seed.expect("`seed` parameter is required"),
+                seed_fn,
+            })
+        }
+    }
+
+    let Args {
+        retry,
+        seed,
+        seed_fn,
+    } = parse_macro_input!(args as Args);
+
+    let seed_fn = seed_fn.iter();
+
+    let func = parse_macro_input!(input as ItemFn);
+    let attrs = &func.attrs;
+    let name = &func.sig.ident;
+
+    TokenStream::from(quote! {
+        #[test]
+        #(#attrs),*
+        fn #name() {
+            #func
+
+            let mut seed = #seed;
+
+            for i in 0..=#retry {
+                let result = std::panic::catch_unwind(|| {
+                    #name(seed);
+                });
+
+                if result.is_ok() {
+                    return;
+                }
+
+                if i == #retry {
+                    std::panic::resume_unwind(result.unwrap_err());
+                }
+
+                #(
+                    seed = #seed_fn();
+                )*
+
+                if i < #retry {
+                    println!("\nRetry {}/{} with a new seed {}", i + 1, #retry, seed);
+                }
+            }
+        }
+    })
+}