fix #137589

Author: jdonszelmann

compiler/rustc_attr_parsing/src/parser.rs

@@ -13,7 +13,7 @@ use rustc_ast_pretty::pprust;
 use rustc_errors::DiagCtxtHandle;
 use rustc_hir::{self as hir, AttrPath};
 use rustc_span::symbol::{Ident, kw};
-use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span, Symbol};
+use rustc_span::{ErrorGuaranteed, Span, Symbol};
 
 pub struct SegmentIterator<'a> {
     offset: usize,
@@ -127,7 +127,7 @@ impl<'a> ArgParser<'a> {
             }
             AttrArgs::Eq { eq_span, expr } => Self::NameValue(NameValueParser {
                 eq_span: *eq_span,
-                value: expr_to_lit(dcx, &expr),
+                value: expr_to_lit(dcx, &expr, value.span().unwrap()),
                 value_span: expr.span,
             }),
         }
@@ -348,16 +348,22 @@ impl NameValueParser {
     }
 }
 
-fn expr_to_lit(dcx: DiagCtxtHandle<'_>, expr: &Expr) -> MetaItemLit {
+fn expr_to_lit(dcx: DiagCtxtHandle<'_>, expr: &Expr, attr_span: Span) -> MetaItemLit {
     // In valid code the value always ends up as a single literal. Otherwise, a dummy
     // literal suffices because the error is handled elsewhere.
     if let ExprKind::Lit(token_lit) = expr.kind
         && let Ok(lit) = MetaItemLit::from_token_lit(token_lit, expr.span)
     {
         lit
     } else {
-        let guar = dcx.has_errors().unwrap();
-        MetaItemLit { symbol: kw::Empty, suffix: None, kind: LitKind::Err(guar), span: DUMMY_SP }
+        let mut err = dcx.struct_span_err(attr_span, "attribute value must be a literal");
+        if let ExprKind::Err(_) = expr.kind {
+            err.downgrade_to_delayed_bug();
+        }
+
+        let e = err.emit();
+
+        MetaItemLit { symbol: kw::Empty, suffix: None, kind: LitKind::Err(e), span: expr.span }
     }
 }
 

tests/ui/attributes/empty-expansion-macro.rs

@@ -0,0 +1,10 @@
+// Tests for the issue in #137589
+
+
+#[crate_type = foo!()] //~ ERROR attribute value must be a literal
+//~^ ERROR cannot find macro `foo` in this scope
+
+macro_rules! foo {} //~ ERROR unexpected end of macro invocation
+
+
+fn main() {}

tests/ui/attributes/empty-expansion-macro.stderr

@@ -0,0 +1,26 @@
+error: attribute value must be a literal
+  --> $DIR/empty-expansion-macro.rs:1:1
+   |
+LL | #[crate_type = foo!()]
+   | ^^^^^^^^^^^^^^
+
+error: unexpected end of macro invocation
+  --> $DIR/empty-expansion-macro.rs:4:1
+   |
+LL | macro_rules! foo {}
+   | ^^^^^^^^^^^^^^^^^^^ missing tokens in macro arguments
+
+error: cannot find macro `foo` in this scope
+  --> $DIR/empty-expansion-macro.rs:1:16
+   |
+LL | #[crate_type = foo!()]
+   |                ^^^ consider moving the definition of `foo` before this call
+   |
+note: a macro with the same name exists, but it appears later
+  --> $DIR/empty-expansion-macro.rs:4:14
+   |
+LL | macro_rules! foo {}
+   |              ^^^
+
+error: aborting due to 3 previous errors
+