Use early attribute parsing for #[path] in rustc_expand

Author: JonathanBrouwer

compiler/rustc_attr_parsing/src/validate_attr.rs

@@ -8,7 +8,7 @@ use rustc_ast::tokenstream::DelimSpan;
 use rustc_ast::{
     self as ast, AttrArgs, Attribute, DelimArgs, MetaItem, MetaItemInner, MetaItemKind, Safety,
 };
-use rustc_errors::{Applicability, FatalError, PResult};
+use rustc_errors::{Applicability, PResult};
 use rustc_feature::{AttributeTemplate, BUILTIN_ATTRIBUTE_MAP, BuiltinAttribute};
 use rustc_hir::AttrPath;
 use rustc_hir::lints::AttributeLintKind;
@@ -231,15 +231,3 @@ fn emit_malformed_attribute(
         err.emit();
     }
 }
-
-pub fn emit_fatal_malformed_builtin_attribute(
-    psess: &ParseSess,
-    attr: &Attribute,
-    name: Symbol,
-) -> ! {
-    let template = BUILTIN_ATTRIBUTE_MAP.get(&name).expect("builtin attr defined").template;
-    emit_malformed_attribute(psess, attr.style, attr.span, name, template);
-    // This is fatal, otherwise it will likely cause a cascade of other errors
-    // (and an error here is expected to be very rare).
-    FatalError.raise()
-}

compiler/rustc_expand/src/module.rs

@@ -2,8 +2,9 @@ use std::iter::once;
 use std::path::{self, Path, PathBuf};
 
 use rustc_ast::{AttrVec, Attribute, Inline, Item, ModSpans};
-use rustc_attr_parsing::validate_attr;
+use rustc_attr_parsing::AttributeParser;
 use rustc_errors::{Diag, ErrorGuaranteed};
+use rustc_hir::attrs::AttributeKind;
 use rustc_parse::lexer::StripTokens;
 use rustc_parse::{exp, new_parser_from_file, unwrap_or_emit_fatal};
 use rustc_session::Session;
@@ -185,19 +186,11 @@ pub(crate) fn mod_file_path_from_attr(
     dir_path: &Path,
 ) -> Option<PathBuf> {
     // Extract path string from first `#[path = "path_string"]` attribute.
-    let first_path = attrs.iter().find(|at| at.has_name(sym::path))?;
-    let Some(path_sym) = first_path.value_str() else {
-        // This check is here mainly to catch attempting to use a macro,
-        // such as `#[path = concat!(...)]`. This isn't supported because
-        // otherwise the `InvocationCollector` would need to defer loading
-        // a module until the `#[path]` attribute was expanded, and it
-        // doesn't support that (and would likely add a bit of complexity).
-        // Usually bad forms are checked during semantic analysis via
-        // `TyCtxt::check_mod_attrs`), but by the time that runs the macro
-        // is expanded, and it doesn't give an error.
-        validate_attr::emit_fatal_malformed_builtin_attribute(&sess.psess, first_path, sym::path);
+    let Some(rustc_hir::Attribute::Parsed(AttributeKind::Path(path_sym, _))) =
+        AttributeParser::parse_limited(sess, attrs, sym::path, None)
+    else {
+        return None;
     };
-
     let path_str = path_sym.as_str();
 
     // On windows, the base path might have the form