7 files changed, 70 insertions, 33 deletions

diff --git a/crates/hir_expand/src/builtin_derive.rs b/crates/hir_expand/src/builtin_derive.rs
index 6ece4b289..537c03028 100644
--- a/crates/hir_expand/src/builtin_derive.rs
+++ b/crates/hir_expand/src/builtin_derive.rs
@@ -269,7 +269,7 @@ mod tests {
     use expect_test::{expect, Expect};
     use name::AsName;
 
-    use crate::{test_db::TestDB, AstId, MacroCallId, MacroCallKind, MacroCallLoc};
+    use crate::{test_db::TestDB, AstId, AttrId, MacroCallId, MacroCallKind, MacroCallLoc};
 
     use super::*;
 
@@ -308,7 +308,7 @@ $0
 
         let expander = BuiltinDeriveExpander::find_by_name(&name).unwrap();
 
-        let attr_id = AstId::new(file_id.into(), ast_id_map.ast_id(&items[0]));
+        let ast_id = AstId::new(file_id.into(), ast_id_map.ast_id(&items[0]));
 
         let loc = MacroCallLoc {
             def: MacroDefId {
@@ -317,7 +317,11 @@ $0
                 local_inner: false,
             },
             krate: CrateId(0),
-            kind: MacroCallKind::Derive(attr_id, name.to_string()),
+            kind: MacroCallKind::Derive {
+                ast_id,
+                derive_name: name.to_string(),
+                derive_attr: AttrId(0),
+            },
         };
 
         let id: MacroCallId = db.intern_macro(loc).into();
diff --git a/crates/hir_expand/src/builtin_macro.rs b/crates/hir_expand/src/builtin_macro.rs
index 4d52904b9..80365fc16 100644
--- a/crates/hir_expand/src/builtin_macro.rs
+++ b/crates/hir_expand/src/builtin_macro.rs
@@ -1,10 +1,10 @@
 //! Builtin macro
 use crate::{
     db::AstDatabase, name, quote, AstId, CrateId, EagerMacroId, LazyMacroId, MacroCallId,
-    MacroDefId, MacroDefKind, TextSize,
+    MacroCallLoc, MacroDefId, MacroDefKind, TextSize,
 };
 
-use base_db::{AnchoredPath, FileId};
+use base_db::{AnchoredPath, Edition, FileId};
 use cfg::CfgExpr;
 use either::Either;
 use mbe::{parse_exprs_with_sep, parse_to_token_tree, ExpandResult};
@@ -111,6 +111,8 @@ register_builtin! {
     (llvm_asm, LlvmAsm) => asm_expand,
     (asm, Asm) => asm_expand,
     (cfg, Cfg) => cfg_expand,
+    (core_panic, CorePanic) => panic_expand,
+    (std_panic, StdPanic) => panic_expand,
 
     EAGER:
     (compile_error, CompileError) => compile_error_expand,
@@ -284,6 +286,25 @@ fn cfg_expand(
     ExpandResult::ok(expanded)
 }
 
+fn panic_expand(
+    db: &dyn AstDatabase,
+    id: LazyMacroId,
+    tt: &tt::Subtree,
+) -> ExpandResult<tt::Subtree> {
+    let loc: MacroCallLoc = db.lookup_intern_macro(id);
+    // Expand to a macro call `$crate::panic::panic_{edition}`
+    let krate = tt::Ident { text: "$crate".into(), id: tt::TokenId::unspecified() };
+    let mut call = if db.crate_graph()[loc.krate].edition == Edition::Edition2021 {
+        quote!(#krate::panic::panic_2021!)
+    } else {
+        quote!(#krate::panic::panic_2015!)
+    };
+
+    // Pass the original arguments
+    call.token_trees.push(tt::TokenTree::Subtree(tt.clone()));
+    ExpandResult::ok(call)
+}
+
 fn unquote_str(lit: &tt::Literal) -> Option<String> {
     let lit = ast::make::tokens::literal(&lit.to_string());
     let token = ast::String::cast(lit)?;
@@ -469,7 +490,7 @@ fn env_expand(
         // unnecessary diagnostics for eg. `CARGO_PKG_NAME`.
         if key == "OUT_DIR" {
             err = Some(mbe::ExpandError::Other(
-                r#"`OUT_DIR` not set, enable "load out dirs from check" to fix"#.into(),
+                r#"`OUT_DIR` not set, enable "run build scripts" to fix"#.into(),
             ));
         }
 
@@ -545,10 +566,9 @@ mod tests {
                 let loc = MacroCallLoc {
                     def,
                     krate,
-                    kind: MacroCallKind::FnLike(AstId::new(
-                        file_id.into(),
-                        ast_id_map.ast_id(&macro_call),
-                    )),
+                    kind: MacroCallKind::FnLike {
+                        ast_id: AstId::new(file_id.into(), ast_id_map.ast_id(&macro_call)),
+                    },
                 };
 
                 let id: MacroCallId = db.intern_macro(loc).into();
@@ -563,7 +583,7 @@ mod tests {
                 };
 
                 let args = macro_call.token_tree().unwrap();
-                let parsed_args = mbe::ast_to_token_tree(&args).unwrap().0;
+                let parsed_args = mbe::ast_to_token_tree(&args).0;
                 let call_id = AstId::new(file_id.into(), ast_id_map.ast_id(&macro_call));
 
                 let arg_id = db.intern_eager_expansion({
diff --git a/crates/hir_expand/src/db.rs b/crates/hir_expand/src/db.rs
index c0ab70b60..ca705ee9d 100644
--- a/crates/hir_expand/src/db.rs
+++ b/crates/hir_expand/src/db.rs
@@ -119,7 +119,7 @@ pub fn expand_hypothetical(
     token_to_map: syntax::SyntaxToken,
 ) -> Option<(SyntaxNode, syntax::SyntaxToken)> {
     let macro_file = MacroFile { macro_call_id: actual_macro_call };
-    let (tt, tmap_1) = mbe::syntax_node_to_token_tree(hypothetical_args.syntax()).unwrap();
+    let (tt, tmap_1) = mbe::syntax_node_to_token_tree(hypothetical_args.syntax());
     let range =
         token_to_map.text_range().checked_sub(hypothetical_args.syntax().text_range().start())?;
     let token_id = tmap_1.token_by_range(range)?;
@@ -143,10 +143,7 @@ fn macro_def(db: &dyn AstDatabase, id: MacroDefId) -> Option<Arc<(TokenExpander,
         MacroDefKind::Declarative(ast_id) => match ast_id.to_node(db) {
             syntax::ast::Macro::MacroRules(macro_rules) => {
                 let arg = macro_rules.token_tree()?;
-                let (tt, tmap) = mbe::ast_to_token_tree(&arg).or_else(|| {
-                    log::warn!("fail on macro_rules to token tree: {:#?}", arg);
-                    None
-                })?;
+                let (tt, tmap) = mbe::ast_to_token_tree(&arg);
                 let rules = match MacroRules::parse(&tt) {
                     Ok(it) => it,
                     Err(err) => {
@@ -159,10 +156,7 @@ fn macro_def(db: &dyn AstDatabase, id: MacroDefId) -> Option<Arc<(TokenExpander,
             }
             syntax::ast::Macro::MacroDef(macro_def) => {
                 let arg = macro_def.body()?;
-                let (tt, tmap) = mbe::ast_to_token_tree(&arg).or_else(|| {
-                    log::warn!("fail on macro_def to token tree: {:#?}", arg);
-                    None
-                })?;
+                let (tt, tmap) = mbe::ast_to_token_tree(&arg);
                 let rules = match MacroDef::parse(&tt) {
                     Ok(it) => it,
                     Err(err) => {
@@ -202,7 +196,7 @@ fn macro_arg_text(db: &dyn AstDatabase, id: MacroCallId) -> Option<GreenNode> {
 
 fn macro_arg(db: &dyn AstDatabase, id: MacroCallId) -> Option<Arc<(tt::Subtree, mbe::TokenMap)>> {
     let arg = db.macro_arg_text(id)?;
-    let (tt, tmap) = mbe::syntax_node_to_token_tree(&SyntaxNode::new_root(arg))?;
+    let (tt, tmap) = mbe::syntax_node_to_token_tree(&SyntaxNode::new_root(arg));
     Some(Arc::new((tt, tmap)))
 }
 
@@ -445,6 +439,7 @@ fn to_fragment_kind(db: &dyn AstDatabase, id: MacroCallId) -> FragmentKind {
     match parent.kind() {
         MACRO_ITEMS | SOURCE_FILE => FragmentKind::Items,
         MACRO_STMTS => FragmentKind::Statements,
+        MACRO_PAT => FragmentKind::Pattern,
         ITEM_LIST => FragmentKind::Items,
         LET_STMT => {
             // FIXME: Handle LHS Pattern
diff --git a/crates/hir_expand/src/eager.rs b/crates/hir_expand/src/eager.rs
index 9eedc8461..ef126e4ad 100644
--- a/crates/hir_expand/src/eager.rs
+++ b/crates/hir_expand/src/eager.rs
@@ -106,7 +106,7 @@ pub fn expand_eager_macro(
     mut diagnostic_sink: &mut dyn FnMut(mbe::ExpandError),
 ) -> Result<EagerMacroId, ErrorEmitted> {
     let parsed_args = diagnostic_sink.option_with(
-        || Some(mbe::ast_to_token_tree(&macro_call.value.token_tree()?)?.0),
+        || Some(mbe::ast_to_token_tree(&macro_call.value.token_tree()?).0),
         || err("malformed macro invocation"),
     )?;
 
@@ -161,7 +161,7 @@ pub fn expand_eager_macro(
 }
 
 fn to_subtree(node: &SyntaxNode) -> Option<tt::Subtree> {
-    let mut subtree = mbe::syntax_node_to_token_tree(node)?.0;
+    let mut subtree = mbe::syntax_node_to_token_tree(node).0;
     subtree.delimiter = None;
     Some(subtree)
 }
@@ -174,8 +174,9 @@ fn lazy_expand(
 ) -> ExpandResult<Option<InFile<SyntaxNode>>> {
     let ast_id = db.ast_id_map(macro_call.file_id).ast_id(&macro_call.value);
 
-    let id: MacroCallId =
-        def.as_lazy_macro(db, krate, MacroCallKind::FnLike(macro_call.with_value(ast_id))).into();
+    let id: MacroCallId = def
+        .as_lazy_macro(db, krate, MacroCallKind::FnLike { ast_id: macro_call.with_value(ast_id) })
+        .into();
 
     let err = db.macro_expand_error(id);
     let value = db.parse_or_expand(id.as_file()).map(|node| InFile::new(id.as_file(), node));
diff --git a/crates/hir_expand/src/lib.rs b/crates/hir_expand/src/lib.rs
index 3e332ee47..a0e6aec62 100644
--- a/crates/hir_expand/src/lib.rs
+++ b/crates/hir_expand/src/lib.rs
@@ -290,22 +290,27 @@ pub struct MacroCallLoc {
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum MacroCallKind {
-    FnLike(AstId<ast::MacroCall>),
-    Derive(AstId<ast::Item>, String),
+    FnLike { ast_id: AstId<ast::MacroCall> },
+    Derive { ast_id: AstId<ast::Item>, derive_name: String, derive_attr: AttrId },
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct AttrId(pub u32);
+
 impl MacroCallKind {
     fn file_id(&self) -> HirFileId {
         match self {
-            MacroCallKind::FnLike(ast_id) => ast_id.file_id,
-            MacroCallKind::Derive(ast_id, _) => ast_id.file_id,
+            MacroCallKind::FnLike { ast_id, .. } => ast_id.file_id,
+            MacroCallKind::Derive { ast_id, .. } => ast_id.file_id,
         }
     }
 
     fn node(&self, db: &dyn db::AstDatabase) -> InFile<SyntaxNode> {
         match self {
-            MacroCallKind::FnLike(ast_id) => ast_id.with_value(ast_id.to_node(db).syntax().clone()),
-            MacroCallKind::Derive(ast_id, _) => {
+            MacroCallKind::FnLike { ast_id, .. } => {
+                ast_id.with_value(ast_id.to_node(db).syntax().clone())
+            }
+            MacroCallKind::Derive { ast_id, .. } => {
                 ast_id.with_value(ast_id.to_node(db).syntax().clone())
             }
         }
@@ -313,10 +318,10 @@ impl MacroCallKind {
 
     fn arg(&self, db: &dyn db::AstDatabase) -> Option<SyntaxNode> {
         match self {
-            MacroCallKind::FnLike(ast_id) => {
+            MacroCallKind::FnLike { ast_id, .. } => {
                 Some(ast_id.to_node(db).token_tree()?.syntax().clone())
             }
-            MacroCallKind::Derive(ast_id, _) => Some(ast_id.to_node(db).syntax().clone()),
+            MacroCallKind::Derive { ast_id, .. } => Some(ast_id.to_node(db).syntax().clone()),
         }
     }
 }
diff --git a/crates/hir_expand/src/name.rs b/crates/hir_expand/src/name.rs
index cd691b1d2..a0f8766b0 100644
--- a/crates/hir_expand/src/name.rs
+++ b/crates/hir_expand/src/name.rs
@@ -55,6 +55,15 @@ impl Name {
         }
     }
 
+    /// A fake name for things missing in the source code.
+    ///
+    /// For example, `impl Foo for {}` should be treated as a trait impl for a
+    /// type with a missing name. Similarly, `struct S { : u32 }` should have a
+    /// single field with a missing name.
+    ///
+    /// Ideally, we want a `gensym` semantics for missing names -- each missing
+    /// name is equal only to itself. It's not clear how to implement this in
+    /// salsa though, so we punt on that bit for a moment.
     pub fn missing() -> Name {
         Name::new_text("[missing name]".into())
     }
@@ -199,6 +208,8 @@ pub mod known {
         line,
         module_path,
         assert,
+        core_panic,
+        std_panic,
         stringify,
         concat,
         include,
diff --git a/crates/hir_expand/src/quote.rs b/crates/hir_expand/src/quote.rs
index 08bc5aa49..c82487ef0 100644
--- a/crates/hir_expand/src/quote.rs
+++ b/crates/hir_expand/src/quote.rs
@@ -104,6 +104,7 @@ macro_rules! __quote {
     ( . ) => {$crate::__quote!(@PUNCT '.')};
     ( < ) => {$crate::__quote!(@PUNCT '<')};
     ( > ) => {$crate::__quote!(@PUNCT '>')};
+    ( ! ) => {$crate::__quote!(@PUNCT '!')};
 
     ( $first:tt $($tail:tt)+ ) => {
         {