Add diagnostic for calling a function with the same name with unresolved Macro

compiler/rustc_resolve/src/macros.rs

@@ -12,7 +12,7 @@ use rustc_attr::StabilityLevel;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::intern::Interned;
 use rustc_data_structures::sync::Lrc;
-use rustc_errors::struct_span_err;
+use rustc_errors::{struct_span_err, Applicability};
 use rustc_expand::base::{Annotatable, DeriveResolutions, Indeterminate, ResolverExpand};
 use rustc_expand::base::{SyntaxExtension, SyntaxExtensionKind};
 use rustc_expand::compile_declarative_macro;
@@ -694,7 +694,19 @@ impl<'a> Resolver<'a> {
                     check_consistency(self, &path, path_span, kind, initial_res, res)
                 }
                 path_res @ PathResult::NonModule(..) | path_res @ PathResult::Failed { .. } => {
+                    let mut suggestion = None;
                     let (span, label) = if let PathResult::Failed { span, label, .. } = path_res {
+                        // try to suggest if it's not a macro, maybe a function
+                        if let PathResult::NonModule(partial_res) = self.maybe_resolve_path(&path, Some(ValueNS), &parent_scope)
+                            && partial_res.unresolved_segments() == 0 {
+                            let sm = self.session.source_map();
+                            let exclamation_span = sm.next_point(span);
+                            suggestion = Some((
+                                vec![(exclamation_span, "".to_string())],
+                                    format!("{} is not a macro, but a {}, try to remove `!`", Segment::names_to_string(&path), partial_res.base_res().descr()),
+                                    Applicability::MaybeIncorrect
+                                ));
+                        }
                         (span, label)
                     } else {
                         (
@@ -708,7 +720,7 @@ impl<'a> Resolver<'a> {
                     };
                     self.report_error(
                         span,
-                        ResolutionError::FailedToResolve { label, suggestion: None },
+                        ResolutionError::FailedToResolve { label, suggestion },
                     );
                 }
                 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),

src/test/ui/suggestions/issue-103112.rs

@@ -0,0 +1,4 @@
+fn main() {
+    std::process::abort!();
+    //~^ ERROR: failed to resolve
+}

src/test/ui/suggestions/issue-103112.stderr

@@ -0,0 +1,15 @@
+error[E0433]: failed to resolve: could not find `abort` in `process`
+  --> $DIR/issue-103112.rs:2:19
+   |
+LL |     std::process::abort!();
+   |                   ^^^^^ could not find `abort` in `process`
+   |
+help: std::process::abort is not a macro, but a function, try to remove `!`
+   |
+LL -     std::process::abort!();
+LL +     std::process::abort();
+   |
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0433`.