Auto merge of #12629 - flodiebold:proc-macro-error-improvement, r=Veykril

fix: 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.

10 files changed, 174 insertions, 170 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 49a73d60f56..22292cdcc67 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -538,6 +538,7 @@ dependencies = [
  "mbe",
  "profile",
  "rustc-hash",
+ "stdx",
  "syntax",
  "tracing",
  "tt",
diff --git a/crates/hir-def/src/nameres/collector.rs b/crates/hir-def/src/nameres/collector.rs
index 1f095846b1c..9901df2af08 100644
--- a/crates/hir-def/src/nameres/collector.rs
+++ b/crates/hir-def/src/nameres/collector.rs
@@ -421,22 +421,22 @@ impl DefCollector<'_> {
         }
     }
 
-    /// When the fixed-point loop reaches a stable state, we might still have some unresolved
-    /// attributes (or unexpanded attribute proc macros) left over. This takes one of them, and
-    /// feeds the item it's applied to back into name resolution.
+    /// When the fixed-point loop reaches a stable state, we might still have
+    /// some unresolved attributes left over. This takes one of them, and feeds
+    /// the item it's applied to back into name resolution.
     ///
     /// This effectively ignores the fact that the macro is there and just treats the items as
     /// normal code.
     ///
-    /// This improves UX when proc macros are turned off or don't work, and replicates the behavior
-    /// before we supported proc. attribute macros.
+    /// This improves UX for unresolved attributes, and replicates the
+    /// behavior before we supported proc. attribute macros.
     fn reseed_with_unresolved_attribute(&mut self) -> ReachedFixedPoint {
         cov_mark::hit!(unresolved_attribute_fallback);
 
         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,
@@ -444,7 +444,7 @@ impl DefCollector<'_> {
                         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 +1229,16 @@ impl DefCollector<'_> {
                     );
                     let loc: MacroCallLoc = self.db.lookup_intern_macro_call(call_id);
 
+                    // If proc attribute macro expansion is disabled, skip expanding it here
+                    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!(
@@ -1245,8 +1251,10 @@ impl DefCollector<'_> {
 
                     if let MacroDefKind::ProcMacro(exp, ..) = loc.def.kind {
                         if exp.is_dummy() {
-                            // Proc macros that cannot be expanded are treated as not
-                            // resolved, in order to fall back later.
+                            // If there's no expander for the proc macro (e.g.
+                            // because proc macros are disabled, or building the
+                            // proc macro crate failed), report this and skip
+                            // expansion like we would if it was disabled
                             self.def_map.diagnostics.push(DefDiagnostic::unresolved_proc_macro(
                                 directive.module_id,
                                 loc.kind,
diff --git a/crates/hir-expand/Cargo.toml b/crates/hir-expand/Cargo.toml
index 9e72f27ea4e..0e6fad16103 100644
--- a/crates/hir-expand/Cargo.toml
+++ b/crates/hir-expand/Cargo.toml
@@ -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" }
diff --git a/crates/hir-expand/src/proc_macro.rs b/crates/hir-expand/src/proc_macro.rs
index b2686592a55..29d78e21ba3 100644
--- a/crates/hir-expand/src/proc_macro.rs
+++ b/crates/hir-expand/src/proc_macro.rs
@@ -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()));
                     }
                 };
 
diff --git a/crates/hir/src/diagnostics.rs b/crates/hir/src/diagnostics.rs
index 1f65c05c1ea..6a06c6b10f5 100644
--- a/crates/hir/src/diagnostics.rs
+++ b/crates/hir/src/diagnostics.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,
 }
 
diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index cc4d14c12da..7a31a8a4173 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.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};
@@ -628,67 +628,7 @@ 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(),
@@ -696,10 +636,11 @@ fn emit_def_diagnostic(db: &dyn HirDatabase, acc: &mut Vec<AnyDiagnostic>, diag:
         }
 
         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,
                     }
diff --git a/crates/ide-diagnostics/src/handlers/macro_error.rs b/crates/ide-diagnostics/src/handlers/macro_error.rs
index 53d0131e02d..83f2bc2237b 100644
--- a/crates/ide-diagnostics/src/handlers/macro_error.rs
+++ b/crates/ide-diagnostics/src/handlers/macro_error.rs
@@ -4,12 +4,12 @@ use crate::{Diagnostic, DiagnosticsContext};
 //
 // This diagnostic is shown for macro expansion errors.
 pub(crate) fn macro_error(ctx: &DiagnosticsContext<'_>, d: &hir::MacroError) -> Diagnostic {
-    Diagnostic::new(
-        "macro-error",
-        d.message.clone(),
-        ctx.sema.diagnostics_display_range(d.node.clone()).range,
-    )
-    .experimental()
+    // Use more accurate position if available.
+    let display_range = d
+        .precise_location
+        .unwrap_or_else(|| ctx.sema.diagnostics_display_range(d.node.clone()).range);
+
+    Diagnostic::new("macro-error", d.message.clone(), display_range).experimental()
 }
 
 #[cfg(test)]
@@ -30,10 +30,10 @@ macro_rules! include { () => {} }
 macro_rules! compile_error { () => {} }
 
   include!("doesntexist");
-//^^^^^^^^^^^^^^^^^^^^^^^^ error: failed to load file `doesntexist`
+//^^^^^^^ error: failed to load file `doesntexist`
 
   compile_error!("compile_error macro works");
-//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ error: compile_error macro works
+//^^^^^^^^^^^^^ error: compile_error macro works
             "#,
         );
     }
@@ -111,7 +111,7 @@ macro_rules! env { () => {} }
 macro_rules! concat { () => {} }
 
   include!(concat!(env!("OUT_DIR"), "/out.rs"));
-//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ error: `OUT_DIR` not set, enable "build scripts" to fix
+//^^^^^^^ error: `OUT_DIR` not set, enable "build scripts" to fix
 "#,
         );
     }
@@ -153,23 +153,23 @@ fn main() {
     // Test a handful of built-in (eager) macros:
 
     include!(invalid);
-  //^^^^^^^^^^^^^^^^^ error: could not convert tokens
+  //^^^^^^^ error: could not convert tokens
     include!("does not exist");
-  //^^^^^^^^^^^^^^^^^^^^^^^^^^ error: failed to load file `does not exist`
+  //^^^^^^^ error: failed to load file `does not exist`
 
     env!(invalid);
-  //^^^^^^^^^^^^^ error: could not convert tokens
+  //^^^ error: could not convert tokens
 
     env!("OUT_DIR");
-  //^^^^^^^^^^^^^^^ error: `OUT_DIR` not set, enable "build scripts" to fix
+  //^^^ error: `OUT_DIR` not set, enable "build scripts" to fix
 
     compile_error!("compile_error works");
-  //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ error: compile_error works
+  //^^^^^^^^^^^^^ error: compile_error works
 
     // Lazy:
 
     format_args!();
-  //^^^^^^^^^^^^^^ error: no rule matches input tokens
+  //^^^^^^^^^^^ error: no rule matches input tokens
 }
 "#,
         );
@@ -186,7 +186,7 @@ fn f() {
     m!();
 
     m!(hi);
-  //^^^^^^ error: leftover tokens
+  //^ error: leftover tokens
 }
       "#,
         );
diff --git a/crates/ide-diagnostics/src/handlers/unresolved_macro_call.rs b/crates/ide-diagnostics/src/handlers/unresolved_macro_call.rs
index 831d082bc7e..4b43124757f 100644
--- a/crates/ide-diagnostics/src/handlers/unresolved_macro_call.rs
+++ b/crates/ide-diagnostics/src/handlers/unresolved_macro_call.rs
@@ -1,6 +1,3 @@
-use hir::{db::AstDatabase, InFile};
-use syntax::{ast, AstNode, SyntaxNodePtr};
-
 use crate::{Diagnostic, DiagnosticsContext};
 
 // Diagnostic: unresolved-macro-call
@@ -11,25 +8,16 @@ pub(crate) fn unresolved_macro_call(
     ctx: &DiagnosticsContext<'_>,
     d: &hir::UnresolvedMacroCall,
 ) -> Diagnostic {
-    let last_path_segment = ctx.sema.db.parse_or_expand(d.macro_call.file_id).and_then(|root| {
-        let node = d.macro_call.value.to_node(&root);
-        if let Some(macro_call) = ast::MacroCall::cast(node) {
-            macro_call
-                .path()
-                .and_then(|it| it.segment())
-                .and_then(|it| it.name_ref())
-                .map(|it| InFile::new(d.macro_call.file_id, SyntaxNodePtr::new(it.syntax())))
-        } else {
-            None
-        }
-    });
-    let diagnostics = last_path_segment.unwrap_or_else(|| d.macro_call.clone().map(|it| it.into()));
+    // Use more accurate position if available.
+    let display_range = d
+        .precise_location
+        .unwrap_or_else(|| ctx.sema.diagnostics_display_range(d.macro_call.clone()).range);
 
     let bang = if d.is_bang { "!" } else { "" };
     Diagnostic::new(
         "unresolved-macro-call",
         format!("unresolved macro `{}{}`", d.path, bang),
-        ctx.sema.diagnostics_display_range(diagnostics).range,
+        display_range,
     )
     .experimental()
 }
diff --git a/crates/project-model/src/tests.rs b/crates/project-model/src/tests.rs
index 6f883b9e846..2e8e93c926c 100644
--- a/crates/project-model/src/tests.rs
+++ b/crates/project-model/src/tests.rs
@@ -172,8 +172,8 @@ fn cargo_hello_world_project_model_with_wildcard_overrides() {
                                 prelude: true,
                             },
                         ],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no build data",
                         ),
                         origin: CratesIo {
                             repo: None,
@@ -247,8 +247,8 @@ fn cargo_hello_world_project_model_with_wildcard_overrides() {
                                 prelude: true,
                             },
                         ],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no build data",
                         ),
                         origin: CratesIo {
                             repo: None,
@@ -312,8 +312,8 @@ fn cargo_hello_world_project_model_with_wildcard_overrides() {
                             },
                         },
                         dependencies: [],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no build data",
                         ),
                         origin: CratesIo {
                             repo: Some(
@@ -389,8 +389,8 @@ fn cargo_hello_world_project_model_with_wildcard_overrides() {
                                 prelude: true,
                             },
                         ],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no build data",
                         ),
                         origin: CratesIo {
                             repo: None,
@@ -464,8 +464,8 @@ fn cargo_hello_world_project_model_with_wildcard_overrides() {
                                 prelude: true,
                             },
                         ],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no build data",
                         ),
                         origin: CratesIo {
                             repo: None,
@@ -554,8 +554,8 @@ fn cargo_hello_world_project_model_with_selective_overrides() {
                                 prelude: true,
                             },
                         ],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no build data",
                         ),
                         origin: CratesIo {
                             repo: None,
@@ -631,8 +631,8 @@ fn cargo_hello_world_project_model_with_selective_overrides() {
                                 prelude: true,
                             },
                         ],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no build data",
                         ),
                         origin: CratesIo {
                             repo: None,
@@ -696,8 +696,8 @@ fn cargo_hello_world_project_model_with_selective_overrides() {
                             },
                         },
                         dependencies: [],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no build data",
                         ),
                         origin: CratesIo {
                             repo: Some(
@@ -775,8 +775,8 @@ fn cargo_hello_world_project_model_with_selective_overrides() {
                                 prelude: true,
                             },
                         ],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no build data",
                         ),
                         origin: CratesIo {
                             repo: None,
@@ -852,8 +852,8 @@ fn cargo_hello_world_project_model_with_selective_overrides() {
                                 prelude: true,
                             },
                         ],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no build data",
                         ),
                         origin: CratesIo {
                             repo: None,
@@ -933,8 +933,8 @@ fn cargo_hello_world_project_model() {
                                 prelude: true,
                             },
                         ],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no build data",
                         ),
                         origin: CratesIo {
                             repo: None,
@@ -1010,8 +1010,8 @@ fn cargo_hello_world_project_model() {
                                 prelude: true,
                             },
                         ],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no build data",
                         ),
                         origin: CratesIo {
                             repo: None,
@@ -1075,8 +1075,8 @@ fn cargo_hello_world_project_model() {
                             },
                         },
                         dependencies: [],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no build data",
                         ),
                         origin: CratesIo {
                             repo: Some(
@@ -1154,8 +1154,8 @@ fn cargo_hello_world_project_model() {
                                 prelude: true,
                             },
                         ],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no build data",
                         ),
                         origin: CratesIo {
                             repo: None,
@@ -1231,8 +1231,8 @@ fn cargo_hello_world_project_model() {
                                 prelude: true,
                             },
                         ],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no build data",
                         ),
                         origin: CratesIo {
                             repo: None,
@@ -1505,8 +1505,8 @@ fn rust_project_hello_world_project_model() {
                                 prelude: false,
                             },
                         ],
-                        proc_macro: Ok(
-                            [],
+                        proc_macro: Err(
+                            "no proc macro dylib present",
                         ),
                         origin: CratesIo {
                             repo: None,
diff --git a/crates/project-model/src/workspace.rs b/crates/project-model/src/workspace.rs
index 6aefb84db8a..18c9c2c8106 100644
--- a/crates/project-model/src/workspace.rs
+++ b/crates/project-model/src/workspace.rs
@@ -459,7 +459,7 @@ fn project_json_to_crate_graph(
                     krate.display_name.as_ref().map(|it| it.canonical_name()).unwrap_or(""),
                     &it,
                 ),
-                None => Ok(Vec::new()),
+                None => Err("no proc macro dylib present".into()),
             };
 
             let target_cfgs = match krate.target.as_deref() {
@@ -870,9 +870,10 @@ fn add_target_crate_root(
         }
     }
 
-    let proc_macro = match build_data.as_ref().and_then(|it| it.proc_macro_dylib_path.as_ref()) {
-        Some(it) => load_proc_macro(it),
-        None => Ok(Vec::new()),
+    let proc_macro = match build_data.as_ref().map(|it| it.proc_macro_dylib_path.as_ref()) {
+        Some(Some(it)) => load_proc_macro(it),
+        Some(None) => Err("no proc macro dylib present".into()),
+        None => Err("no build data".into()),
     };
 
     let display_name = CrateDisplayName::from_canonical_name(cargo_name.to_string());