9 files changed, 159 insertions, 80 deletions

diff --git a/crates/ide_assists/src/handlers/remove_unused_param.rs b/crates/ide_assists/src/handlers/remove_unused_param.rs
index 2699d2861..fabfe7e93 100644
--- a/crates/ide_assists/src/handlers/remove_unused_param.rs
+++ b/crates/ide_assists/src/handlers/remove_unused_param.rs
@@ -37,8 +37,20 @@ pub(crate) fn remove_unused_param(acc: &mut Assists, ctx: &AssistContext) -> Opt
         _ => return None,
     };
     let func = param.syntax().ancestors().find_map(ast::Fn::cast)?;
-    let param_position = func.param_list()?.params().position(|it| it == param)?;
 
+    // check if fn is in impl Trait for ..
+    if func
+        .syntax()
+        .parent() // AssocItemList
+        .and_then(|x| x.parent())
+        .and_then(ast::Impl::cast)
+        .map_or(false, |imp| imp.trait_().is_some())
+    {
+        cov_mark::hit!(trait_impl);
+        return None;
+    }
+
+    let param_position = func.param_list()?.params().position(|it| it == param)?;
     let fn_def = {
         let func = ctx.sema.to_def(&func)?;
         Definition::ModuleDef(func.into())
@@ -254,6 +266,22 @@ fn main() { foo(9, 2) }
     }
 
     #[test]
+    fn trait_impl() {
+        cov_mark::check!(trait_impl);
+        check_assist_not_applicable(
+            remove_unused_param,
+            r#"
+trait Trait {
+    fn foo(x: i32);
+}
+impl Trait for () {
+    fn foo($0x: i32) {}
+}
+"#,
+        );
+    }
+
+    #[test]
     fn remove_across_files() {
         check_assist(
             remove_unused_param,
diff --git a/crates/proc_macro_srv/src/dylib.rs b/crates/proc_macro_srv/src/dylib.rs
index cccc53220..5133e7c50 100644
--- a/crates/proc_macro_srv/src/dylib.rs
+++ b/crates/proc_macro_srv/src/dylib.rs
@@ -188,7 +188,9 @@ impl Expander {
 /// Copy the dylib to temp directory to prevent locking in Windows
 #[cfg(windows)]
 fn ensure_file_with_lock_free_access(path: &Path) -> io::Result<PathBuf> {
-    use std::{ffi::OsString, time::SystemTime};
+    use std::collections::hash_map::RandomState;
+    use std::ffi::OsString;
+    use std::hash::{BuildHasher, Hasher};
 
     let mut to = std::env::temp_dir();
 
@@ -199,10 +201,11 @@ fn ensure_file_with_lock_free_access(path: &Path) -> io::Result<PathBuf> {
         )
     })?;
 
-    // generate a time deps unique number
-    let t = SystemTime::now().duration_since(std::time::UNIX_EPOCH).expect("Time went backwards");
+    // Generate a unique number by abusing `HashMap`'s hasher.
+    // Maybe this will also "inspire" a libs team member to finally put `rand` in libstd.
+    let t = RandomState::new().build_hasher().finish();
 
-    let mut unique_name = OsString::from(t.as_millis().to_string());
+    let mut unique_name = OsString::from(t.to_string());
     unique_name.push(file_name);
 
     to.push(unique_name);
diff --git a/crates/proc_macro_srv/src/tests/utils.rs b/crates/proc_macro_srv/src/tests/utils.rs
index 2e950c113..2c093aa0a 100644
--- a/crates/proc_macro_srv/src/tests/utils.rs
+++ b/crates/proc_macro_srv/src/tests/utils.rs
@@ -7,35 +7,8 @@ use proc_macro_api::ListMacrosTask;
 use std::str::FromStr;
 
 pub mod fixtures {
-    use cargo_metadata::Message;
-    use std::path::PathBuf;
-    use std::process::Command;
-
-    // Use current project metadata to get the proc-macro dylib path
     pub fn proc_macro_test_dylib_path() -> std::path::PathBuf {
-        let name = "proc_macro_test";
-        let version = "0.0.0";
-        let command = Command::new(toolchain::cargo())
-            .args(&["check", "--tests", "--message-format", "json"])
-            .output()
-            .unwrap()
-            .stdout;
-
-        for message in Message::parse_stream(command.as_slice()) {
-            match message.unwrap() {
-                Message::CompilerArtifact(artifact) => {
-                    if artifact.target.kind.contains(&"proc-macro".to_string()) {
-                        let repr = format!("{} {}", name, version);
-                        if artifact.package_id.repr.starts_with(&repr) {
-                            return PathBuf::from(&artifact.filenames[0]);
-                        }
-                    }
-                }
-                _ => (), // Unknown message
-            }
-        }
-
-        panic!("No proc-macro dylib for {} found!", name);
+        proc_macro_test::PROC_MACRO_TEST_LOCATION.into()
     }
 }
 
diff --git a/crates/proc_macro_test/Cargo.toml b/crates/proc_macro_test/Cargo.toml
index 753443be2..1a88e361e 100644
--- a/crates/proc_macro_test/Cargo.toml
+++ b/crates/proc_macro_test/Cargo.toml
@@ -8,4 +8,8 @@ publish = false
 
 [lib]
 doctest = false
-proc-macro = true
+
+[build-dependencies]
+proc_macro_test_impl = { path = "imp", version = "0.0.0" }
+toolchain = { path = "../toolchain", version = "0.0.0" }
+cargo_metadata = "0.13"
diff --git a/crates/proc_macro_test/build.rs b/crates/proc_macro_test/build.rs
new file mode 100644
index 000000000..4653a93dd
--- /dev/null
+++ b/crates/proc_macro_test/build.rs
@@ -0,0 +1,48 @@
+//! This will build the proc macro in `imp`, and copy the resulting dylib artifact into the
+//! `OUT_DIR`.
+//!
+//! `proc_macro_test` itself contains only a path to that artifact.
+
+use std::{
+    env, fs,
+    path::{Path, PathBuf},
+    process::Command,
+};
+
+use cargo_metadata::Message;
+
+fn main() {
+    let out_dir = env::var_os("OUT_DIR").unwrap();
+    let out_dir = Path::new(&out_dir);
+
+    let name = "proc_macro_test_impl";
+    let version = "0.0.0";
+    let output = Command::new(toolchain::cargo())
+        .current_dir("imp")
+        .args(&["build", "-p", "proc_macro_test_impl", "--message-format", "json"])
+        .output()
+        .unwrap();
+    assert!(output.status.success());
+
+    let mut artifact_path = None;
+    for message in Message::parse_stream(output.stdout.as_slice()) {
+        match message.unwrap() {
+            Message::CompilerArtifact(artifact) => {
+                if artifact.target.kind.contains(&"proc-macro".to_string()) {
+                    let repr = format!("{} {}", name, version);
+                    if artifact.package_id.repr.starts_with(&repr) {
+                        artifact_path = Some(PathBuf::from(&artifact.filenames[0]));
+                    }
+                }
+            }
+            _ => (), // Unknown message
+        }
+    }
+
+    let src_path = artifact_path.expect("no dylib for proc_macro_test_impl found");
+    let dest_path = out_dir.join(src_path.file_name().unwrap());
+    fs::copy(src_path, &dest_path).unwrap();
+
+    let info_path = out_dir.join("proc_macro_test_location.txt");
+    fs::write(info_path, dest_path.to_str().unwrap()).unwrap();
+}
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()
+}
diff --git a/crates/proc_macro_test/src/lib.rs b/crates/proc_macro_test/src/lib.rs
index 4b26d2472..2edf23a63 100644
--- a/crates/proc_macro_test/src/lib.rs
+++ b/crates/proc_macro_test/src/lib.rs
@@ -1,48 +1,4 @@
 //! 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()
-}
+pub static PROC_MACRO_TEST_LOCATION: &str =
+    include_str!(concat!(env!("OUT_DIR"), "/proc_macro_test_location.txt"));