Check single literal

Author: kjeremy

crates/ra_hir/src/ty/tests.rs

@@ -4895,3 +4895,26 @@ fn main() {
     "###
     );
 }
+
+#[test]
+fn infer_builtin_macros_compile_error() {
+    assert_snapshot!(
+        infer(r#"
+#[rustc_builtin_macro]
+macro_rules! compile_error {
+    ($msg:expr) => ({ /* compiler built-in */ });
+    ($msg:expr,) => ({ /* compiler built-in */ })
+}
+
+fn main() {
+    compile_error!("error!");
+}
+"#),
+        @r###"
+    ![0; 14) 'loop{"error!"}': !
+    ![4; 14) '{"error!"}': &str
+    ![5; 13) '"error!"': &str
+    [166; 199) '{     ...!"); }': !
+    "###
+    );
+}

crates/ra_hir_expand/src/builtin_macro.rs

@@ -177,25 +177,21 @@ fn file_expand(
 }
 
 fn compile_error_expand(
-    db: &dyn AstDatabase,
-    id: MacroCallId,
-    _tt: &tt::Subtree,
+    _db: &dyn AstDatabase,
+    _id: MacroCallId,
+    tt: &tt::Subtree,
 ) -> Result<tt::Subtree, mbe::ExpandError> {
-    let loc = db.lookup_intern_macro(id);
-    let macro_call = loc.ast_id.to_node(db);
-
-    let macro_content = {
-        // FIXME: verify that this is an ast::Literatal with kind() == LiteralKind.String, else error.
-        let arg = macro_call.token_tree().ok_or_else(|| mbe::ExpandError::UnexpectedToken)?;
-        let macro_args = arg.syntax().clone();
-        let text = macro_args.text();
-        let without_parens = TextUnit::of_char('(')..text.len() - TextUnit::of_char(')');
-        text.slice(without_parens).to_string()
-    };
-
-    let expanded = quote! {
-        loop { #macro_content }
-    };
+    if tt.count() == 1 {
+        match &tt.token_trees[0] {
+            tt::TokenTree::Leaf(tt::Leaf::Literal(it)) => {
+                let s = it.text.as_str();
+                if s.starts_with(r#"""#) && s.ends_with(r#"""#) {
+                    return Ok(quote! { loop { #it }});
+                }
+            },
+            _ => {},
+        };
+    }
 
-    Ok(expanded)
+    Err(mbe::ExpandError::BindingError("Must be a string".into()))
 }