Merge #9192

9192: internal: Build test-macros in a build script r=jonas-schievink a=jonas-schievink

This build the test-proc-macros in `proc_macro_test` in a build script, and copies the artifact to `OUT_DIR`. This should make it available throughout all of rust-analyzer at no cost other than depending on `proc_macro_test`, fixing https://github.com/rust-analyzer/rust-analyzer/issues/9067.

This hopefully will let us later write inline tests that utilize proc macros, which makes my life fixing proc macro bugs easier.

Opening this as a sort of RFC, because I'm not totally sure this approach is the best.

Co-authored-by: Jonas Schievink <[email protected]>

3 files changed, 67 insertions, 0 deletions

diff --git a/crates/proc_macro_test/imp/.gitignore b/crates/proc_macro_test/imp/.gitignore
new file mode 100644
index 000000000..2c96eb1b6
--- /dev/null
+++ b/crates/proc_macro_test/imp/.gitignore
@@ -0,0 +1,2 @@
+target/
+Cargo.lock
diff --git a/crates/proc_macro_test/imp/Cargo.toml b/crates/proc_macro_test/imp/Cargo.toml
new file mode 100644
index 000000000..1c2e75401
--- /dev/null
+++ b/crates/proc_macro_test/imp/Cargo.toml
@@ -0,0 +1,17 @@
+[package]
+name = "proc_macro_test_impl"
+version = "0.0.0"
+license = "MIT OR Apache-2.0"
+authors = ["rust-analyzer developers"]
+edition = "2018"
+publish = false
+
+[lib]
+doctest = false
+proc-macro = true
+
+[workspace]
+
+[dependencies]
+# this crate should not have any dependencies, since it uses its own workspace,
+# and its own `Cargo.lock`
diff --git a/crates/proc_macro_test/imp/src/lib.rs b/crates/proc_macro_test/imp/src/lib.rs
new file mode 100644
index 000000000..4b26d2472
--- /dev/null
+++ b/crates/proc_macro_test/imp/src/lib.rs
@@ -0,0 +1,48 @@
+//! Exports a few trivial procedural macros for testing.
+
+use proc_macro::TokenStream;
+
+#[proc_macro]
+pub fn fn_like_noop(args: TokenStream) -> TokenStream {
+    args
+}
+
+#[proc_macro]
+pub fn fn_like_panic(args: TokenStream) -> TokenStream {
+    panic!("fn_like_panic!({})", args);
+}
+
+#[proc_macro]
+pub fn fn_like_error(args: TokenStream) -> TokenStream {
+    format!("compile_error!(\"fn_like_error!({})\");", args).parse().unwrap()
+}
+
+#[proc_macro_attribute]
+pub fn attr_noop(_args: TokenStream, item: TokenStream) -> TokenStream {
+    item
+}
+
+#[proc_macro_attribute]
+pub fn attr_panic(args: TokenStream, item: TokenStream) -> TokenStream {
+    panic!("#[attr_panic {}] {}", args, item);
+}
+
+#[proc_macro_attribute]
+pub fn attr_error(args: TokenStream, item: TokenStream) -> TokenStream {
+    format!("compile_error!(\"#[attr_error({})] {}\");", args, item).parse().unwrap()
+}
+
+#[proc_macro_derive(DeriveEmpty)]
+pub fn derive_empty(_item: TokenStream) -> TokenStream {
+    TokenStream::new()
+}
+
+#[proc_macro_derive(DerivePanic)]
+pub fn derive_panic(item: TokenStream) -> TokenStream {
+    panic!("#[derive(DerivePanic)] {}", item);
+}
+
+#[proc_macro_derive(DeriveError)]
+pub fn derive_error(item: TokenStream) -> TokenStream {
+    format!("compile_error!(\"#[derive(DeriveError)] {}\");", item).parse().unwrap()
+}