4 files changed, 21 insertions, 7 deletions

diff --git a/crates/hir_expand/src/db.rs b/crates/hir_expand/src/db.rs
index 46ebdbc74..ff50bfd82 100644
--- a/crates/hir_expand/src/db.rs
+++ b/crates/hir_expand/src/db.rs
@@ -3,7 +3,7 @@
 use std::sync::Arc;
 
 use base_db::{salsa, SourceDatabase};
-use mbe::{ExpandResult, MacroRules};
+use mbe::{ExpandError, ExpandResult, MacroRules};
 use parser::FragmentKind;
 use syntax::{algo::diff, AstNode, GreenNode, Parse, SyntaxKind::*, SyntaxNode};
 
@@ -81,6 +81,9 @@ pub trait AstDatabase: SourceDatabase {
     ) -> ExpandResult<Option<(Parse<SyntaxNode>, Arc<mbe::TokenMap>)>>;
     fn macro_expand(&self, macro_call: MacroCallId) -> ExpandResult<Option<Arc<tt::Subtree>>>;
 
+    /// Firewall query that returns the error from the `macro_expand` query.
+    fn macro_expand_error(&self, macro_call: MacroCallId) -> Option<ExpandError>;
+
     #[salsa::interned]
     fn intern_eager_expansion(&self, eager: EagerCallLoc) -> EagerMacroId;
 
@@ -171,6 +174,10 @@ fn macro_expand(db: &dyn AstDatabase, id: MacroCallId) -> ExpandResult<Option<Ar
     macro_expand_with_arg(db, id, None)
 }
 
+fn macro_expand_error(db: &dyn AstDatabase, macro_call: MacroCallId) -> Option<ExpandError> {
+    db.macro_expand(macro_call).err
+}
+
 fn expander(db: &dyn AstDatabase, id: MacroCallId) -> Option<Arc<(TokenExpander, mbe::TokenMap)>> {
     let lazy_id = match id {
         MacroCallId::LazyMacro(id) => id,
@@ -189,6 +196,7 @@ fn macro_expand_with_arg(
     id: MacroCallId,
     arg: Option<Arc<(tt::Subtree, mbe::TokenMap)>>,
 ) -> ExpandResult<Option<Arc<tt::Subtree>>> {
+    let _p = profile::span("macro_expand");
     let lazy_id = match id {
         MacroCallId::LazyMacro(id) => id,
         MacroCallId::EagerMacro(id) => {
@@ -276,14 +284,15 @@ fn parse_macro_with_arg(
     macro_file: MacroFile,
     arg: Option<Arc<(tt::Subtree, mbe::TokenMap)>>,
 ) -> ExpandResult<Option<(Parse<SyntaxNode>, Arc<mbe::TokenMap>)>> {
-    let _p = profile::span("parse_macro_query");
-
     let macro_call_id = macro_file.macro_call_id;
     let result = if let Some(arg) = arg {
         macro_expand_with_arg(db, macro_call_id, Some(arg))
     } else {
         db.macro_expand(macro_call_id)
     };
+
+    let _p = profile::span("parse_macro_expansion");
+
     if let Some(err) = &result.err {
         // Note:
         // The final goal we would like to make all parse_macro success,
diff --git a/crates/hir_expand/src/diagnostics.rs b/crates/hir_expand/src/diagnostics.rs
index 1043c6aeb..bf0b85ce9 100644
--- a/crates/hir_expand/src/diagnostics.rs
+++ b/crates/hir_expand/src/diagnostics.rs
@@ -5,7 +5,7 @@
 //!
 //! `DiagnosticSink` struct is used as an emitter for diagnostic. When creating
 //! a `DiagnosticSink`, you supply a callback which can react to a `dyn
-//! Diagnostic` or to any concrete diagnostic (downcasting is sued internally).
+//! Diagnostic` or to any concrete diagnostic (downcasting is used internally).
 //!
 //! Because diagnostics store file offsets, it's a bad idea to store them
 //! directly in salsa. For this reason, every hir subsytem defines it's own
@@ -32,7 +32,12 @@ impl DiagnosticCode {
 pub trait Diagnostic: Any + Send + Sync + fmt::Debug + 'static {
     fn code(&self) -> DiagnosticCode;
     fn message(&self) -> String;
-    /// Used in highlighting and related purposes
+    /// Source element that triggered the diagnostics.
+    ///
+    /// Note that this should reflect "semantics", rather than specific span we
+    /// want to highlight. When rendering the diagnostics into an error message,
+    /// the IDE will fetch the `SyntaxNode` and will narrow the span
+    /// appropriately.
     fn display_source(&self) -> InFile<SyntaxNodePtr>;
     fn as_any(&self) -> &(dyn Any + Send + 'static);
     fn is_experimental(&self) -> bool {
diff --git a/crates/hir_expand/src/lib.rs b/crates/hir_expand/src/lib.rs
index d5ba691b7..6dad2507b 100644
--- a/crates/hir_expand/src/lib.rs
+++ b/crates/hir_expand/src/lib.rs
@@ -255,7 +255,7 @@ pub enum MacroDefKind {
 pub struct MacroCallLoc {
     pub(crate) def: MacroDefId,
     pub(crate) krate: CrateId,
-    pub(crate) kind: MacroCallKind,
+    pub kind: MacroCallKind,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
diff --git a/crates/hir_expand/src/proc_macro.rs b/crates/hir_expand/src/proc_macro.rs
index 7505cb061..97edf0fb6 100644
--- a/crates/hir_expand/src/proc_macro.rs
+++ b/crates/hir_expand/src/proc_macro.rs
@@ -50,7 +50,7 @@ impl ProcMacroExpander {
 
                 proc_macro.expander.expand(&tt, None).map_err(mbe::ExpandError::from)
             }
-            None => Err(err!("Unresolved proc macro")),
+            None => Err(mbe::ExpandError::UnresolvedProcMacro),
         }
     }
 }