2 files changed, 165 insertions, 0 deletions

diff --git a/crates/ide/src/diagnostics.rs b/crates/ide/src/diagnostics.rs
index f7965326d..c257ea8e7 100644
--- a/crates/ide/src/diagnostics.rs
+++ b/crates/ide/src/diagnostics.rs
@@ -9,6 +9,7 @@ mod unresolved_extern_crate;
 mod unresolved_import;
 mod unresolved_macro_call;
 mod unresolved_proc_macro;
+mod macro_error;
 mod inactive_code;
 mod missing_fields;
 
@@ -229,6 +230,7 @@ pub(crate) fn diagnostics(
             AnyDiagnostic::UnresolvedMacroCall(d) => unresolved_macro_call::unresolved_macro_call(&ctx, &d),
             AnyDiagnostic::UnresolvedProcMacro(d) => unresolved_proc_macro::unresolved_proc_macro(&ctx, &d),
             AnyDiagnostic::MissingFields(d) => missing_fields::missing_fields(&ctx, &d),
+            AnyDiagnostic::MacroError(d) => macro_error::macro_error(&ctx, &d),
 
             AnyDiagnostic::InactiveCode(d) => match inactive_code::inactive_code(&ctx, &d) {
                 Some(it) => it,
diff --git a/crates/ide/src/diagnostics/macro_error.rs b/crates/ide/src/diagnostics/macro_error.rs
new file mode 100644
index 000000000..8cc8cfb48
--- /dev/null
+++ b/crates/ide/src/diagnostics/macro_error.rs
@@ -0,0 +1,163 @@
+use crate::diagnostics::{Diagnostic, DiagnosticsContext};
+
+// Diagnostic: macro-error
+//
+// This diagnostic is shown for macro expansion errors.
+pub(super) 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()
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::diagnostics::tests::{check_diagnostics, check_no_diagnostics};
+
+    #[test]
+    fn builtin_macro_fails_expansion() {
+        check_diagnostics(
+            r#"
+#[rustc_builtin_macro]
+macro_rules! include { () => {} }
+
+  include!("doesntexist");
+//^^^^^^^^^^^^^^^^^^^^^^^^ failed to load file `doesntexist`
+            "#,
+        );
+    }
+
+    #[test]
+    fn include_macro_should_allow_empty_content() {
+        check_diagnostics(
+            r#"
+//- /lib.rs
+#[rustc_builtin_macro]
+macro_rules! include { () => {} }
+
+include!("foo/bar.rs");
+//- /foo/bar.rs
+// empty
+"#,
+        );
+    }
+
+    #[test]
+    fn good_out_dir_diagnostic() {
+        check_diagnostics(
+            r#"
+#[rustc_builtin_macro]
+macro_rules! include { () => {} }
+#[rustc_builtin_macro]
+macro_rules! env { () => {} }
+#[rustc_builtin_macro]
+macro_rules! concat { () => {} }
+
+  include!(concat!(env!("OUT_DIR"), "/out.rs"));
+//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `OUT_DIR` not set, enable "run build scripts" to fix
+"#,
+        );
+    }
+
+    #[test]
+    fn register_attr_and_tool() {
+        cov_mark::check!(register_attr);
+        cov_mark::check!(register_tool);
+        check_no_diagnostics(
+            r#"
+#![register_tool(tool)]
+#![register_attr(attr)]
+
+#[tool::path]
+#[attr]
+struct S;
+"#,
+        );
+        // NB: we don't currently emit diagnostics here
+    }
+
+    #[test]
+    fn macro_diag_builtin() {
+        check_diagnostics(
+            r#"
+#[rustc_builtin_macro]
+macro_rules! env {}
+
+#[rustc_builtin_macro]
+macro_rules! include {}
+
+#[rustc_builtin_macro]
+macro_rules! compile_error {}
+
+#[rustc_builtin_macro]
+macro_rules! format_args { () => {} }
+
+fn main() {
+    // Test a handful of built-in (eager) macros:
+
+    include!(invalid);
+  //^^^^^^^^^^^^^^^^^ could not convert tokens
+    include!("does not exist");
+  //^^^^^^^^^^^^^^^^^^^^^^^^^^ failed to load file `does not exist`
+
+    env!(invalid);
+  //^^^^^^^^^^^^^ could not convert tokens
+
+    env!("OUT_DIR");
+  //^^^^^^^^^^^^^^^ `OUT_DIR` not set, enable "run build scripts" to fix
+
+    compile_error!("compile_error works");
+  //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ compile_error works
+
+    // Lazy:
+
+    format_args!();
+  //^^^^^^^^^^^^^^ no rule matches input tokens
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn macro_rules_diag() {
+        check_diagnostics(
+            r#"
+macro_rules! m {
+    () => {};
+}
+fn f() {
+    m!();
+
+    m!(hi);
+  //^^^^^^ leftover tokens
+}
+      "#,
+        );
+    }
+    #[test]
+    fn dollar_crate_in_builtin_macro() {
+        check_diagnostics(
+            r#"
+#[macro_export]
+#[rustc_builtin_macro]
+macro_rules! format_args {}
+
+#[macro_export]
+macro_rules! arg { () => {} }
+
+#[macro_export]
+macro_rules! outer {
+    () => {
+        $crate::format_args!( "", $crate::arg!(1) )
+    };
+}
+
+fn f() {
+    outer!();
+} //^^^^^^^^ leftover tokens
+"#,
+        )
+    }
+}