Rollup merge of #145322 - LorrensP-2158466:early-prelude-processing, r=petrochenkov

Resolve the prelude import in `build_reduced_graph`
This pr tries to resolve the prelude import at the `build_reduced_graph` stage.
Part of batched import resolution in #145108 (cherry picked commit) and maybe needed for #139493.
r? petrochenkov

Author: Zalathar

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -493,9 +493,6 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
 });
 }
 }
-// We don't add prelude imports to the globs since they only affect lexical scopes,
-// which are not relevant to import resolution.
-ImportKind::Glob{is_prelude:true, .. } => {}
 ImportKind::Glob{ .. } => current_module.globs.borrow_mut().push(import),
  _ => unreachable!(),
 }
@@ -658,13 +655,19 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
 self.add_import(module_path, kind, use_tree.span, item, root_span, item.id, vis);
 }
  ast::UseTreeKind::Glob => {
-let kind = ImportKind::Glob{
-is_prelude: ast::attr::contains_name(&item.attrs, sym::prelude_import),
-max_vis:Cell::new(None),
- id,
-};
-
-self.add_import(prefix, kind, use_tree.span, item, root_span, item.id, vis);
+if !ast::attr::contains_name(&item.attrs, sym::prelude_import){
+let kind = ImportKind::Glob{max_vis:Cell::new(None), id };
+self.add_import(prefix, kind, use_tree.span, item, root_span, item.id, vis);
+}else{
+// Resolve the prelude import early.
+let path_res =
+self.r.cm().maybe_resolve_path(&prefix,None,&self.parent_scope,None);
+ifletPathResult::Module(ModuleOrUniformRoot::Module(module)) = path_res {
+self.r.prelude = Some(module);
+}else{
+self.r.dcx().span_err(use_tree.span,"cannot resolve a prelude import");
+}
+}
 }
  ast::UseTreeKind::Nested{ref items, .. } => {
 // Ensure there is at most one `self` in the list

compiler/rustc_resolve/src/imports.rs

@@ -87,7 +87,6 @@ pub(crate) enum ImportKind<'ra> {
 id:NodeId,
 },
 Glob{
-is_prelude:bool,
 // The visibility of the greatest re-export.
 // n.b. `max_vis` is only used in `finalize_import` to check for re-export errors.
 max_vis:Cell<Option<Visibility>>,
@@ -125,12 +124,9 @@ impl<'ra> std::fmt::Debug for ImportKind<'ra> {
 .field("nested", nested)
 .field("id", id)
 .finish(),
-Glob{ is_prelude, max_vis, id } => f
-.debug_struct("Glob")
-.field("is_prelude", is_prelude)
-.field("max_vis", max_vis)
-.field("id", id)
-.finish(),
+Glob{ max_vis, id } => {
+ f.debug_struct("Glob").field("max_vis", max_vis).field("id", id).finish()
+}
 ExternCrate{ source, target, id } => f
 .debug_struct("ExternCrate")
 .field("source", source)
@@ -1073,7 +1069,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 ImportKind::Single{ source, target,ref bindings, type_ns_only, id, .. } => {
 (source, target, bindings, type_ns_only, id)
 }
-ImportKind::Glob{is_prelude,ref max_vis, id } => {
+ImportKind::Glob{ref max_vis, id } => {
 if import.module_path.len() <= 1{
 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
 // 2 segments, so the `resolve_path` above won't trigger it.
@@ -1096,8 +1092,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 module:None,
 });
 }
-if !is_prelude
- && letSome(max_vis) = max_vis.get()
+ifletSome(max_vis) = max_vis.get()
  && !max_vis.is_at_least(import.vis,self.tcx)
 {
 let def_id = self.local_def_id(id);
@@ -1485,7 +1480,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
 fnresolve_glob_import(&mutself,import:Import<'ra>){
 // This function is only called for glob imports.
-letImportKind::Glob{ id,is_prelude,.. } = import.kindelse{unreachable!()};
+letImportKind::Glob{ id, .. } = import.kindelse{unreachable!()};
 
 letModuleOrUniformRoot::Module(module) = import.imported_module.get().unwrap()else{
 self.dcx().emit_err(CannotGlobImportAllCrates{span: import.span});
@@ -1504,9 +1499,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
 if module == import.parent_scope.module{
 return;
-}elseif is_prelude {
-self.prelude = Some(module);
-return;
 }
 
 // Add to module's glob_importers

library/core/src/lib.rs

@@ -208,6 +208,10 @@
 #[allow(unused_extern_crates)]
 externcrate self as core;
 
+/* The core prelude, not as all-encompassing as the std prelude */
+// The compiler expects the prelude definition to be defined before it's use statement.
+pubmod prelude;
+
 #[prelude_import]
 #[allow(unused)]
 use prelude::rust_2024::*;
@@ -293,10 +297,6 @@ pub mod f64;
 #[macro_use]
 pubmod num;
 
-/* The core prelude, not as all-encompassing as the std prelude */
-
-pubmod prelude;
-
 /* Core modules for ownership management */
 
 pubmod hint;

library/std/src/lib.rs

@@ -428,6 +428,10 @@
 //
 #![default_lib_allocator]
 
+// The Rust prelude
+// The compiler expects the prelude definition to be defined before it's use statement.
+pubmod prelude;
+
 // Explicitly import the prelude. The compiler uses this same unstable attribute
 // to import the prelude implicitly when building crates that depend on std.
 #[prelude_import]
@@ -483,9 +487,6 @@ mod macros;
 #[macro_use]
 pubmod rt;
 
-// The Rust prelude
-pubmod prelude;
-
 #[stable(feature = "rust1", since = "1.0.0")]
 pubuse core::any;
 #[stable(feature = "core_array", since = "1.35.0")]

tests/ui/extern-flag/empty-extern-arg.rs

@@ -1,4 +1,5 @@
 //~ ERROR extern location for std does not exist
+//~^ ERROR cannot resolve a prelude import
 //@ compile-flags: --extern std=
 //@ needs-unwind since it affects the error output
 //@ ignore-emscripten missing eh_catch_typeinfo lang item

tests/ui/extern-flag/empty-extern-arg.stderr

@@ -1,11 +1,13 @@
 error: extern location for std does not exist: 
 
+error: cannot resolve a prelude import
+
 error: `#[panic_handler]` function required, but not found
 
 error: unwinding panics are not supported without std
  |
  = help: using nightly cargo, use -Zbuild-std with panic="abort" to avoid unwinding
  = note: since the core library is usually precompiled with panic="unwind", rebuilding your crate with panic="abort" may not be enough to fix the problem
 
-error: aborting due to 3 previous errors
+error: aborting due to 4 previous errors
 

tests/ui/proc-macro/derive-helper-legacy-spurious.rs

@@ -6,7 +6,7 @@
 externcrate test_macros;
 
 #[derive(Empty)]
-#[empty_helper]//~ ERROR cannot find attribute `empty_helper` in this scope
+#[empty_helper]
 structFoo{}
 
 fnmain(){}

tests/ui/proc-macro/derive-helper-legacy-spurious.stderr

@@ -4,11 +4,5 @@ error: cannot find attribute `dummy` in this scope
 LL | #![dummy]
  | ^^^^^
 
-error: cannot find attribute `empty_helper` in this scope
- --> $DIR/derive-helper-legacy-spurious.rs:9:3
- |
-LL | #[empty_helper]
- | ^^^^^^^^^^^^
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 

tests/ui/resolve/inner-attr-prelude-macro.rs

@@ -0,0 +1,11 @@
+//@ check-pass
+//! This test checks that macro names resolved from the libstd prelude
+//! still work even if there's a crate-level custom inner attribute.
+
+#![feature(custom_inner_attributes)]
+
+#![rustfmt::skip]
+
+fnmain(){
+let _ = todo!();
+}

tests/ui/unpretty/exhaustive.expanded.stdout

@@ -34,9 +34,6 @@ extern crate std;
 #[prelude_import]
 use std::prelude::rust_2024::*;
 
-#[prelude_import]
-use self::prelude::*;
-
 mod prelude {
  pub use std::prelude::rust_2024::*;
 
@@ -47,6 +44,9 @@ mod prelude {
  }
 }
 
+#[prelude_import]
+use self::prelude::*;
+
 mod attributes {
  //! inner single-line doc comment
  /*!