Improve proc macro errors a bit

Distinguish between
 - there is no build data (for some reason?)
 - there is build data, but the cargo package didn't build a proc macro dylib
 - there is a proc macro dylib, but it didn't contain the proc macro we expected
 - the name did not resolve to any macro (this is now an
 unresolved_macro_call even for attributes)

I changed the handling of disabled attribute macro expansion to
immediately ignore the macro and report an unresolved_proc_macro,
because otherwise they would now result in loud unresolved_macro_call
errors. I hope this doesn't break anything.

Also try to improve error ranges for unresolved_macro_call / macro_error
by reusing the code for unresolved_proc_macro. It's not perfect but
probably better than before.

Author: flodiebold

Cargo.lock

@@ -436,15 +436,15 @@ impl DefCollector<'_> {
         let mut unresolved_macros = mem::take(&mut self.unresolved_macros);
         let pos = unresolved_macros.iter().position(|directive| {
             if let MacroDirectiveKind::Attr { ast_id, mod_item, attr, tree } = &directive.kind {
-                self.def_map.diagnostics.push(DefDiagnostic::unresolved_proc_macro(
+                self.def_map.diagnostics.push(DefDiagnostic::unresolved_macro_call(
                     directive.module_id,
                     MacroCallKind::Attr {
                         ast_id: ast_id.ast_id,
                         attr_args: Default::default(),
                         invoc_attr_index: attr.id.ast_index,
                         is_derive: false,
                     },
-                    None,
+                    attr.path().clone(),
                 ));
 
                 self.skip_attrs.insert(ast_id.ast_id.with_value(*mod_item), attr.id);
@@ -1218,10 +1218,6 @@ impl DefCollector<'_> {
                         return recollect_without(self);
                     }
 
-                    if !self.db.enable_proc_attr_macros() {
-                        return true;
-                    }
-
                     // Not resolved to a derive helper or the derive attribute, so try to treat as a normal attribute.
                     let call_id = attr_macro_as_call_id(
                         self.db,
@@ -1233,6 +1229,15 @@ impl DefCollector<'_> {
                     );
                     let loc: MacroCallLoc = self.db.lookup_intern_macro_call(call_id);
 
+                    if !self.db.enable_proc_attr_macros() {
+                        self.def_map.diagnostics.push(DefDiagnostic::unresolved_proc_macro(
+                            directive.module_id,
+                            loc.kind,
+                            Some(loc.def.krate),
+                        ));
+                        return recollect_without(self);
+                    }
+
                     // Skip #[test]/#[bench] expansion, which would merely result in more memory usage
                     // due to duplicating functions into macro expansions
                     if matches!(

crates/hir-def/src/nameres/collector.rs

@@ -20,6 +20,7 @@ hashbrown = { version = "0.12.1", features = [
     "inline-more",
 ], default-features = false }
 
+stdx = { path = "../stdx", version = "0.0.0" }
 base-db = { path = "../base-db", version = "0.0.0" }
 cfg = { path = "../cfg", version = "0.0.0" }
 syntax = { path = "../syntax", version = "0.0.0" }

crates/hir-expand/Cargo.toml

@@ -1,6 +1,7 @@
 //! Proc Macro Expander stub
 
 use base_db::{CrateId, ProcMacroExpansionError, ProcMacroId, ProcMacroKind};
+use stdx::never;
 
 use crate::{db::AstDatabase, ExpandError, ExpandResult};
 
@@ -36,18 +37,20 @@ impl ProcMacroExpander {
                 let krate_graph = db.crate_graph();
                 let proc_macros = match &krate_graph[self.krate].proc_macro {
                     Ok(proc_macros) => proc_macros,
-                    Err(e) => {
-                        return ExpandResult::only_err(ExpandError::Other(
-                            e.clone().into_boxed_str(),
-                        ))
+                    Err(_) => {
+                        never!("Non-dummy expander even though there are no proc macros");
+                        return ExpandResult::only_err(ExpandError::Other("Internal error".into()));
                     }
                 };
                 let proc_macro = match proc_macros.get(id.0 as usize) {
                     Some(proc_macro) => proc_macro,
                     None => {
-                        return ExpandResult::only_err(ExpandError::Other(
-                            "No proc-macro found.".into(),
-                        ))
+                        never!(
+                            "Proc macro index out of bounds: the length is {} but the index is {}",
+                            proc_macros.len(),
+                            id.0
+                        );
+                        return ExpandResult::only_err(ExpandError::Other("Internal error".into()));
                     }
                 };
 

crates/hir-expand/src/proc_macro.rs

@@ -69,6 +69,7 @@ pub struct UnresolvedImport {
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct UnresolvedMacroCall {
     pub macro_call: InFile<SyntaxNodePtr>,
+    pub precise_location: Option<TextRange>,
     pub path: ModPath,
     pub is_bang: bool,
 }
@@ -95,6 +96,7 @@ pub struct UnresolvedProcMacro {
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct MacroError {
     pub node: InFile<SyntaxNodePtr>,
+    pub precise_location: Option<TextRange>,
     pub message: String,
 }
 

crates/hir/src/diagnostics.rs

@@ -73,7 +73,7 @@ use rustc_hash::FxHashSet;
 use stdx::{format_to, impl_from, never};
 use syntax::{
     ast::{self, HasAttrs as _, HasDocComments, HasName},
-    AstNode, AstPtr, SmolStr, SyntaxNodePtr, T,
+    AstNode, AstPtr, SmolStr, SyntaxNodePtr, TextRange, T,
 };
 
 use crate::db::{DefDatabase, HirDatabase};
@@ -628,78 +628,19 @@ fn emit_def_diagnostic(db: &dyn HirDatabase, acc: &mut Vec<AnyDiagnostic>, diag:
         }
 
         DefDiagnosticKind::UnresolvedProcMacro { ast, krate } => {
-            let (node, precise_location, macro_name, kind) = match ast {
-                MacroCallKind::FnLike { ast_id, .. } => {
-                    let node = ast_id.to_node(db.upcast());
-                    (
-                        ast_id.with_value(SyntaxNodePtr::from(AstPtr::new(&node))),
-                        node.path().map(|it| it.syntax().text_range()),
-                        node.path().and_then(|it| it.segment()).map(|it| it.to_string()),
-                        MacroKind::ProcMacro,
-                    )
-                }
-                MacroCallKind::Derive { ast_id, derive_attr_index, derive_index } => {
-                    let node = ast_id.to_node(db.upcast());
-                    // Compute the precise location of the macro name's token in the derive
-                    // list.
-                    let token = (|| {
-                        let derive_attr = node
-                            .doc_comments_and_attrs()
-                            .nth(*derive_attr_index as usize)
-                            .and_then(Either::left)?;
-                        let token_tree = derive_attr.meta()?.token_tree()?;
-                        let group_by = token_tree
-                            .syntax()
-                            .children_with_tokens()
-                            .filter_map(|elem| match elem {
-                                syntax::NodeOrToken::Token(tok) => Some(tok),
-                                _ => None,
-                            })
-                            .group_by(|t| t.kind() == T![,]);
-                        let (_, mut group) = group_by
-                            .into_iter()
-                            .filter(|&(comma, _)| !comma)
-                            .nth(*derive_index as usize)?;
-                        group.find(|t| t.kind() == T![ident])
-                    })();
-                    (
-                        ast_id.with_value(SyntaxNodePtr::from(AstPtr::new(&node))),
-                        token.as_ref().map(|tok| tok.text_range()),
-                        token.as_ref().map(ToString::to_string),
-                        MacroKind::Derive,
-                    )
-                }
-                MacroCallKind::Attr { ast_id, invoc_attr_index, .. } => {
-                    let node = ast_id.to_node(db.upcast());
-                    let attr = node
-                        .doc_comments_and_attrs()
-                        .nth((*invoc_attr_index) as usize)
-                        .and_then(Either::left)
-                        .unwrap_or_else(|| panic!("cannot find attribute #{}", invoc_attr_index));
-
-                    (
-                        ast_id.with_value(SyntaxNodePtr::from(AstPtr::new(&attr))),
-                        Some(attr.syntax().text_range()),
-                        attr.path()
-                            .and_then(|path| path.segment())
-                            .and_then(|seg| seg.name_ref())
-                            .as_ref()
-                            .map(ToString::to_string),
-                        MacroKind::Attr,
-                    )
-                }
-            };
+            let (node, precise_location, macro_name, kind) = precise_macro_call_location(ast, db);
             acc.push(
                 UnresolvedProcMacro { node, precise_location, macro_name, kind, krate: *krate }
                     .into(),
             );
         }
 
         DefDiagnosticKind::UnresolvedMacroCall { ast, path } => {
-            let node = ast.to_node(db.upcast());
+            let (node, precise_location, _, _) = precise_macro_call_location(ast, db);
             acc.push(
                 UnresolvedMacroCall {
-                    macro_call: InFile::new(node.file_id, SyntaxNodePtr::new(&node.value)),
+                    macro_call: node,
+                    precise_location,
                     path: path.clone(),
                     is_bang: matches!(ast, MacroCallKind::FnLike { .. }),
                 }
@@ -708,23 +649,8 @@ fn emit_def_diagnostic(db: &dyn HirDatabase, acc: &mut Vec<AnyDiagnostic>, diag:
         }
 
         DefDiagnosticKind::MacroError { ast, message } => {
-            let node = match ast {
-                MacroCallKind::FnLike { ast_id, .. } => {
-                    let node = ast_id.to_node(db.upcast());
-                    ast_id.with_value(SyntaxNodePtr::from(AstPtr::new(&node)))
-                }
-                MacroCallKind::Derive { ast_id, .. } => {
-                    // FIXME: point to the attribute instead, this creates very large diagnostics
-                    let node = ast_id.to_node(db.upcast());
-                    ast_id.with_value(SyntaxNodePtr::from(AstPtr::new(&node)))
-                }
-                MacroCallKind::Attr { ast_id, .. } => {
-                    // FIXME: point to the attribute instead, this creates very large diagnostics
-                    let node = ast_id.to_node(db.upcast());
-                    ast_id.with_value(SyntaxNodePtr::from(AstPtr::new(&node)))
-                }
-            };
-            acc.push(MacroError { node, message: message.clone() }.into());
+            let (node, precise_location, _, _) = precise_macro_call_location(ast, db);
+            acc.push(MacroError { node, precise_location, message: message.clone() }.into());
         }
 
         DefDiagnosticKind::UnimplementedBuiltinMacro { ast } => {
@@ -771,6 +697,78 @@ fn emit_def_diagnostic(db: &dyn HirDatabase, acc: &mut Vec<AnyDiagnostic>, diag:
     }
 }
 
+fn precise_macro_call_location(
+    ast: &MacroCallKind,
+    db: &dyn HirDatabase,
+) -> (InFile<SyntaxNodePtr>, Option<TextRange>, Option<String>, MacroKind) {
+    // FIXME: maaybe we actually want slightly different ranges for the different macro diagnostics
+    // - e.g. the full attribute for macro errors, but only the name for name resolution
+    match ast {
+        MacroCallKind::FnLike { ast_id, .. } => {
+            let node = ast_id.to_node(db.upcast());
+            (
+                ast_id.with_value(SyntaxNodePtr::from(AstPtr::new(&node))),
+                node.path()
+                    .and_then(|it| it.segment())
+                    .and_then(|it| it.name_ref())
+                    .map(|it| it.syntax().text_range()),
+                node.path().and_then(|it| it.segment()).map(|it| it.to_string()),
+                MacroKind::ProcMacro,
+            )
+        }
+        MacroCallKind::Derive { ast_id, derive_attr_index, derive_index } => {
+            let node = ast_id.to_node(db.upcast());
+            // Compute the precise location of the macro name's token in the derive
+            // list.
+            let token = (|| {
+                let derive_attr = node
+                    .doc_comments_and_attrs()
+                    .nth(*derive_attr_index as usize)
+                    .and_then(Either::left)?;
+                let token_tree = derive_attr.meta()?.token_tree()?;
+                let group_by = token_tree
+                    .syntax()
+                    .children_with_tokens()
+                    .filter_map(|elem| match elem {
+                        syntax::NodeOrToken::Token(tok) => Some(tok),
+                        _ => None,
+                    })
+                    .group_by(|t| t.kind() == T![,]);
+                let (_, mut group) = group_by
+                    .into_iter()
+                    .filter(|&(comma, _)| !comma)
+                    .nth(*derive_index as usize)?;
+                group.find(|t| t.kind() == T![ident])
+            })();
+            (
+                ast_id.with_value(SyntaxNodePtr::from(AstPtr::new(&node))),
+                token.as_ref().map(|tok| tok.text_range()),
+                token.as_ref().map(ToString::to_string),
+                MacroKind::Derive,
+            )
+        }
+        MacroCallKind::Attr { ast_id, invoc_attr_index, .. } => {
+            let node = ast_id.to_node(db.upcast());
+            let attr = node
+                .doc_comments_and_attrs()
+                .nth((*invoc_attr_index) as usize)
+                .and_then(Either::left)
+                .unwrap_or_else(|| panic!("cannot find attribute #{}", invoc_attr_index));
+
+            (
+                ast_id.with_value(SyntaxNodePtr::from(AstPtr::new(&attr))),
+                Some(attr.syntax().text_range()),
+                attr.path()
+                    .and_then(|path| path.segment())
+                    .and_then(|seg| seg.name_ref())
+                    .as_ref()
+                    .map(ToString::to_string),
+                MacroKind::Attr,
+            )
+        }
+    }
+}
+
 impl HasVisibility for Module {
     fn visibility(&self, db: &dyn HirDatabase) -> Visibility {
         let def_map = self.id.def_map(db.upcast());
@@ -1156,6 +1154,7 @@ impl DefWithBody {
                 BodyDiagnostic::MacroError { node, message } => acc.push(
                     MacroError {
                         node: node.clone().map(|it| it.into()),
+                        precise_location: None,
                         message: message.to_string(),
                     }
                     .into(),
@@ -1173,6 +1172,7 @@ impl DefWithBody {
                 BodyDiagnostic::UnresolvedMacroCall { node, path } => acc.push(
                     UnresolvedMacroCall {
                         macro_call: node.clone().map(|ast_ptr| ast_ptr.into()),
+                        precise_location: None,
                         path: path.clone(),
                         is_bang: true,
                     }