Merge #8048

8048: Fix missing unresolved macro diagnostic in function body r=edwin0cheng a=brandondong

This was an issue I found while working on https://github.com/rust-analyzer/rust-analyzer/pull/7970.

**Reproduction:**
1. Call a non-existent macro in a function body.
```
fn main() {
  foo!();
}
```
2. No diagnostics are raised. An unresolved-macro-call diagnostic is expected.
3. If the macro call is instead outside of the function body, this works as expected.

I believe this worked previously and regressed in https://github.com/rust-analyzer/rust-analyzer/pull/7805.

**Behavior prior to https://github.com/rust-analyzer/rust-analyzer/pull/7805:**
- The unresolved-macro-call diagnostic did not exist. Instead, a macro-error diagnostic would be raised with the text "could not resolve macro [path]".
- This was implemented by adding an error to the error sink (https://github.com/rust-analyzer/rust-analyzer/pull/7805/files#diff-50a326c5ae465bd9b31ee4310186380aa06e4fa1f6b41dbc0aed5bcc656a3cb8L657).
- The error was propagated through https://github.com/rust-analyzer/rust-analyzer/blob/1a82af3527e476d52410ff4dfd2fb4c57466abcb/crates/hir_def/src/body.rs#L123 eventually reaching https://github.com/rust-analyzer/rust-analyzer/blob/1a82af3527e476d52410ff4dfd2fb4c57466abcb/crates/hir_def/src/body/lower.rs#L569.

**Behavior after:**
- Instead of writing to the error sink, an UnresolvedMacro error is now returned (https://github.com/rust-analyzer/rust-analyzer/pull/7805/files#diff-50a326c5ae465bd9b31ee4310186380aa06e4fa1f6b41dbc0aed5bcc656a3cb8R631).
- The parent caller throws away the error as its function signature is `Option<MacroCallId>` (https://github.com/rust-analyzer/rust-analyzer/pull/7805/files#diff-50a326c5ae465bd9b31ee4310186380aa06e4fa1f6b41dbc0aed5bcc656a3cb8R604).
- We instead now reach the warn condition (https://github.com/rust-analyzer/rust-analyzer/blob/1a82af3527e476d52410ff4dfd2fb4c57466abcb/crates/hir_def/src/body.rs#L124) and no diagnostics are created in https://github.com/rust-analyzer/rust-analyzer/blob/1a82af3527e476d52410ff4dfd2fb4c57466abcb/crates/hir_def/src/body/lower.rs#L575.

**Fix:**
- Make sure to propagate the UnresolvedMacro error. Report the error using the new unresolved-macro-call diagnostic.


Co-authored-by: Brandon <[email protected]>

3 files changed, 30 insertions, 3 deletions

diff --git a/crates/hir_def/src/body/diagnostics.rs b/crates/hir_def/src/body/diagnostics.rs
index 1de7d30e2..f6992c9a8 100644
--- a/crates/hir_def/src/body/diagnostics.rs
+++ b/crates/hir_def/src/body/diagnostics.rs
@@ -2,13 +2,14 @@
 
 use hir_expand::diagnostics::DiagnosticSink;
 
-use crate::diagnostics::{InactiveCode, MacroError, UnresolvedProcMacro};
+use crate::diagnostics::{InactiveCode, MacroError, UnresolvedMacroCall, UnresolvedProcMacro};
 
 #[derive(Debug, Eq, PartialEq)]
 pub(crate) enum BodyDiagnostic {
     InactiveCode(InactiveCode),
     MacroError(MacroError),
     UnresolvedProcMacro(UnresolvedProcMacro),
+    UnresolvedMacroCall(UnresolvedMacroCall),
 }
 
 impl BodyDiagnostic {
@@ -23,6 +24,9 @@ impl BodyDiagnostic {
             BodyDiagnostic::UnresolvedProcMacro(diag) => {
                 sink.push(diag.clone());
             }
+            BodyDiagnostic::UnresolvedMacroCall(diag) => {
+                sink.push(diag.clone());
+            }
         }
     }
 }
diff --git a/crates/hir_def/src/body/lower.rs b/crates/hir_def/src/body/lower.rs
index 7052058f2..60b25db56 100644
--- a/crates/hir_def/src/body/lower.rs
+++ b/crates/hir_def/src/body/lower.rs
@@ -24,7 +24,7 @@ use crate::{
     body::{Body, BodySourceMap, Expander, LabelSource, PatPtr, SyntheticSyntax},
     builtin_type::{BuiltinFloat, BuiltinInt, BuiltinUint},
     db::DefDatabase,
-    diagnostics::{InactiveCode, MacroError, UnresolvedProcMacro},
+    diagnostics::{InactiveCode, MacroError, UnresolvedMacroCall, UnresolvedProcMacro},
     expr::{
         dummy_expr_id, ArithOp, Array, BinaryOp, BindingAnnotation, CmpOp, Expr, ExprId, Label,
         LabelId, Literal, LogicOp, MatchArm, Ordering, Pat, PatId, RecordFieldPat, RecordLitField,
@@ -33,7 +33,7 @@ use crate::{
     item_scope::BuiltinShadowMode,
     path::{GenericArgs, Path},
     type_ref::{Mutability, Rawness, TypeRef},
-    AdtId, BlockLoc, ModuleDefId,
+    AdtId, BlockLoc, ModuleDefId, UnresolvedMacro,
 };
 
 use super::{diagnostics::BodyDiagnostic, ExprSource, PatSource};
@@ -554,6 +554,17 @@ impl ExprCollector<'_> {
         let macro_call = self.expander.to_source(AstPtr::new(&e));
         let res = self.expander.enter_expand(self.db, e);
 
+        let res = match res {
+            Ok(res) => res,
+            Err(UnresolvedMacro) => {
+                self.source_map.diagnostics.push(BodyDiagnostic::UnresolvedMacroCall(
+                    UnresolvedMacroCall { file: outer_file, node: syntax_ptr.cast().unwrap() },
+                ));
+                collector(self, None);
+                return;
+            }
+        };
+
         match &res.err {
             Some(ExpandError::UnresolvedProcMacro) => {
                 self.source_map.diagnostics.push(BodyDiagnostic::UnresolvedProcMacro(
diff --git a/crates/hir_def/src/body/tests.rs b/crates/hir_def/src/body/tests.rs
index 991a32b15..f8e6f70e8 100644
--- a/crates/hir_def/src/body/tests.rs
+++ b/crates/hir_def/src/body/tests.rs
@@ -175,6 +175,18 @@ fn f() {
 }
 
 #[test]
+fn unresolved_macro_diag() {
+    check_diagnostics(
+        r#"
+fn f() {
+    m!();
+  //^^^^ unresolved macro call
+}
+      "#,
+    );
+}
+
+#[test]
 fn dollar_crate_in_builtin_macro() {
     check_diagnostics(
         r#"