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]>

1 files changed, 1 insertions, 1 deletions

diff --git a/crates/hir_expand/src/eager.rs b/crates/hir_expand/src/eager.rs
index ae7b51a08..dc618a9ee 100644
--- a/crates/hir_expand/src/eager.rs
+++ b/crates/hir_expand/src/eager.rs
@@ -35,7 +35,7 @@ pub struct ErrorEmitted {
     _private: (),
 }
 
-trait ErrorSink {
+pub trait ErrorSink {
     fn emit(&mut self, err: mbe::ExpandError);
 
     fn option<T>(