Rollup of 7 pull requests

.gitignore

@@ -21,6 +21,7 @@ Session.vim
 .project
 .favorites.json
 .settings/
+.vs/
 
 ## Tool
 .valgrindrc

compiler/rustc_builtin_macros/src/cmdline_attrs.rs

@@ -6,7 +6,7 @@ use rustc_ast::{self as ast, AttrItem, AttrStyle};
 use rustc_session::parse::ParseSess;
 use rustc_span::FileName;
 
-pub fn inject(mut krate: ast::Crate, parse_sess: &ParseSess, attrs: &[String]) -> ast::Crate {
+pub fn inject(krate: &mut ast::Crate, parse_sess: &ParseSess, attrs: &[String]) {
     for raw_attr in attrs {
         let mut parser = rustc_parse::new_parser_from_source_str(
             parse_sess,
@@ -36,6 +36,4 @@ pub fn inject(mut krate: ast::Crate, parse_sess: &ParseSess, attrs: &[String]) -
             start_span.to(end_span),
         ));
     }
-
-    krate
 }

compiler/rustc_builtin_macros/src/proc_macro_harness.rs

@@ -44,14 +44,14 @@ struct CollectProcMacros<'a> {
 }
 
 pub fn inject(
+    krate: &mut ast::Crate,
     sess: &Session,
     resolver: &mut dyn ResolverExpand,
-    mut krate: ast::Crate,
     is_proc_macro_crate: bool,
     has_proc_macro_decls: bool,
     is_test_crate: bool,
     handler: &rustc_errors::Handler,
-) -> ast::Crate {
+) {
     let ecfg = ExpansionConfig::default("proc_macro".to_string());
     let mut cx = ExtCtxt::new(sess, ecfg, resolver, None);
 
@@ -66,22 +66,20 @@ pub fn inject(
     };
 
     if has_proc_macro_decls || is_proc_macro_crate {
-        visit::walk_crate(&mut collect, &krate);
+        visit::walk_crate(&mut collect, krate);
     }
     let macros = collect.macros;
 
     if !is_proc_macro_crate {
-        return krate;
+        return;
     }
 
     if is_test_crate {
-        return krate;
+        return;
     }
 
     let decls = mk_decls(&mut cx, &macros);
     krate.items.push(decls);
-
-    krate
 }
 
 impl<'a> CollectProcMacros<'a> {

compiler/rustc_builtin_macros/src/standard_library_imports.rs

@@ -9,17 +9,19 @@ use rustc_span::DUMMY_SP;
 use thin_vec::thin_vec;
 
 pub fn inject(
-    mut krate: ast::Crate,
+    krate: &mut ast::Crate,
+    pre_configured_attrs: &[ast::Attribute],
     resolver: &mut dyn ResolverExpand,
     sess: &Session,
-) -> ast::Crate {
+) -> usize {
+    let orig_num_items = krate.items.len();
     let edition = sess.parse_sess.edition;
 
     // the first name in this list is the crate name of the crate with the prelude
-    let names: &[Symbol] = if sess.contains_name(&krate.attrs, sym::no_core) {
-        return krate;
-    } else if sess.contains_name(&krate.attrs, sym::no_std) {
-        if sess.contains_name(&krate.attrs, sym::compiler_builtins) {
+    let names: &[Symbol] = if sess.contains_name(pre_configured_attrs, sym::no_core) {
+        return 0;
+    } else if sess.contains_name(pre_configured_attrs, sym::no_std) {
+        if sess.contains_name(pre_configured_attrs, sym::compiler_builtins) {
             &[sym::core]
         } else {
             &[sym::core, sym::compiler_builtins]
@@ -88,6 +90,5 @@ pub fn inject(
     );
 
     krate.items.insert(0, use_item);
-
-    krate
+    krate.items.len() - orig_num_items
 }

compiler/rustc_builtin_macros/src/test.rs

@@ -8,7 +8,7 @@ use rustc_errors::Applicability;
 use rustc_expand::base::*;
 use rustc_session::Session;
 use rustc_span::symbol::{sym, Ident, Symbol};
-use rustc_span::Span;
+use rustc_span::{FileNameDisplayPreference, Span};
 use std::iter;
 use thin_vec::{thin_vec, ThinVec};
 
@@ -231,6 +231,8 @@ pub fn expand_test_or_bench(
         &item.ident,
     ));
 
+    let location_info = get_location_info(cx, &item);
+
     let mut test_const = cx.item(
         sp,
         Ident::new(item.ident.name, sp),
@@ -280,6 +282,16 @@ pub fn expand_test_or_bench(
                                             cx.expr_none(sp)
                                         },
                                     ),
+                                    // source_file: <relative_path_of_source_file>
+                                    field("source_file", cx.expr_str(sp, location_info.0)),
+                                    // start_line: start line of the test fn identifier.
+                                    field("start_line", cx.expr_usize(sp, location_info.1)),
+                                    // start_col: start column of the test fn identifier.
+                                    field("start_col", cx.expr_usize(sp, location_info.2)),
+                                    // end_line: end line of the test fn identifier.
+                                    field("end_line", cx.expr_usize(sp, location_info.3)),
+                                    // end_col: end column of the test fn identifier.
+                                    field("end_col", cx.expr_usize(sp, location_info.4)),
                                     // compile_fail: true | false
                                     field("compile_fail", cx.expr_bool(sp, false)),
                                     // no_run: true | false
@@ -364,6 +376,19 @@ pub fn expand_test_or_bench(
     }
 }
 
+fn get_location_info(cx: &ExtCtxt<'_>, item: &ast::Item) -> (Symbol, usize, usize, usize, usize) {
+    let span = item.ident.span;
+    let (source_file, lo_line, lo_col, hi_line, hi_col) =
+        cx.sess.source_map().span_to_location_info(span);
+
+    let file_name = match source_file {
+        Some(sf) => sf.name.display(FileNameDisplayPreference::Remapped).to_string(),
+        None => "no-location".to_string(),
+    };
+
+    (Symbol::intern(&file_name), lo_line, lo_col, hi_line, hi_col)
+}
+
 fn item_path(mod_path: &[Ident], item_ident: &Ident) -> String {
     mod_path
         .iter()

compiler/rustc_builtin_macros/src/test_harness.rs

@@ -37,7 +37,7 @@ struct TestCtxt<'a> {
 
 /// Traverse the crate, collecting all the test functions, eliding any
 /// existing main functions, and synthesizing a main test harness
-pub fn inject(sess: &Session, resolver: &mut dyn ResolverExpand, krate: &mut ast::Crate) {
+pub fn inject(krate: &mut ast::Crate, sess: &Session, resolver: &mut dyn ResolverExpand) {
     let span_diagnostic = sess.diagnostic();
     let panic_strategy = sess.panic_strategy();
     let platform_panic_strategy = sess.target.panic_strategy;

compiler/rustc_driver_impl/src/lib.rs

@@ -353,7 +353,7 @@ fn run_compiler(
 
             {
                 let plugins = queries.register_plugins()?;
-                let (_, lint_store) = &*plugins.borrow();
+                let (.., lint_store) = &*plugins.borrow();
 
                 // Lint plugins are registered; now we can process command line flags.
                 if sess.opts.describe_lints {

compiler/rustc_error_codes/src/error_codes.rs

@@ -513,6 +513,7 @@ E0790: include_str!("./error_codes/E0790.md"),
 E0791: include_str!("./error_codes/E0791.md"),
 E0792: include_str!("./error_codes/E0792.md"),
 E0793: include_str!("./error_codes/E0793.md"),
+E0794: include_str!("./error_codes/E0794.md"),
 }
 
 // Undocumented removed error codes. Note that many removed error codes are documented.

compiler/rustc_error_codes/src/error_codes/E0794.md

@@ -0,0 +1,64 @@
+A lifetime parameter of a function definition is called *late-bound* if it both:
+
+1. appears in an argument type
+2. does not appear in a generic type constraint
+
+You cannot specify lifetime arguments for late-bound lifetime parameters.
+
+Erroneous code example:
+
+```compile_fail,E0794
+fn foo<'a>(x: &'a str) -> &'a str { x }
+let _ = foo::<'static>;
+```
+
+The type of a concrete instance of a generic function is universally quantified
+over late-bound lifetime parameters. This is because we want the function to
+work for any lifetime substituted for the late-bound lifetime parameter, no
+matter where the function is called. Consequently, it doesn't make sense to
+specify arguments for late-bound lifetime parameters, since they are not
+resolved until the function's call site(s).
+
+To fix the issue, remove the specified lifetime:
+
+```
+fn foo<'a>(x: &'a str) -> &'a str { x }
+let _ = foo;
+```
+
+### Additional information
+
+Lifetime parameters that are not late-bound are called *early-bound*.
+Confusion may arise from the fact that late-bound and early-bound
+lifetime parameters are declared the same way in function definitions.
+When referring to a function pointer type, universal quantification over
+late-bound lifetime parameters can be made explicit:
+
+```
+trait BarTrait<'a> {}
+
+struct Bar<'a> {
+    s: &'a str
+}
+
+impl<'a> BarTrait<'a> for Bar<'a> {}
+
+fn bar<'a, 'b, T>(x: &'a str, _t: T) -> &'a str
+where T: BarTrait<'b>
+{
+    x
+}
+
+let bar_fn: for<'a> fn(&'a str, Bar<'static>) -> &'a str = bar; // OK
+let bar_fn2 = bar::<'static, Bar>; // Not allowed
+let bar_fn3 = bar::<Bar>; // OK
+```
+
+In the definition of `bar`, the lifetime parameter `'a` is late-bound, while
+`'b` is early-bound. This is reflected in the type annotation for `bar_fn`,
+where `'a` is universally quantified and `'b` is substituted by a specific
+lifetime. It is not allowed to explicitly specify early-bound lifetime
+arguments when late-bound lifetime parameters are present (as for `bar_fn2`,
+see issue #42868: https://github.com/rust-lang/rust/issues/42868), although the
+types that are constrained by early-bound parameters can be specified (as for
+`bar_fn3`).

compiler/rustc_expand/src/base.rs

@@ -1004,6 +1004,7 @@ pub struct ExpansionData {
 pub struct ExtCtxt<'a> {
     pub sess: &'a Session,
     pub ecfg: expand::ExpansionConfig<'a>,
+    pub num_standard_library_imports: usize,
     pub reduced_recursion_limit: Option<Limit>,
     pub root_path: PathBuf,
     pub resolver: &'a mut dyn ResolverExpand,
@@ -1032,6 +1033,7 @@ impl<'a> ExtCtxt<'a> {
         ExtCtxt {
             sess,
             ecfg,
+            num_standard_library_imports: 0,
             reduced_recursion_limit: None,
             resolver,
             lint_store,

compiler/rustc_expand/src/config.rs

@@ -24,7 +24,6 @@ use rustc_session::Session;
 use rustc_span::edition::{Edition, ALL_EDITIONS};
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::{Span, DUMMY_SP};
-use thin_vec::ThinVec;
 
 /// A folder that strips out items that do not belong in the current configuration.
 pub struct StripUnconfigured<'a> {
@@ -37,7 +36,7 @@ pub struct StripUnconfigured<'a> {
     pub lint_node_id: NodeId,
 }
 
-fn get_features(sess: &Session, krate_attrs: &[ast::Attribute]) -> Features {
+pub fn features(sess: &Session, krate_attrs: &[Attribute]) -> Features {
     fn feature_removed(sess: &Session, span: Span, reason: Option<&str>) {
         sess.emit_err(FeatureRemoved {
             span,
@@ -191,39 +190,16 @@ fn get_features(sess: &Session, krate_attrs: &[ast::Attribute]) -> Features {
     features
 }
 
-/// `cfg_attr`-process the crate's attributes and compute the crate's features.
-pub fn features(
-    sess: &Session,
-    mut krate: ast::Crate,
-    lint_node_id: NodeId,
-) -> (ast::Crate, Features) {
-    let mut strip_unconfigured =
-        StripUnconfigured { sess, features: None, config_tokens: false, lint_node_id };
-
-    let unconfigured_attrs = krate.attrs.clone();
-    let diag = &sess.parse_sess.span_diagnostic;
-    let err_count = diag.err_count();
-    let features = match strip_unconfigured.configure_krate_attrs(krate.attrs) {
-        None => {
-            // The entire crate is unconfigured.
-            krate.attrs = ast::AttrVec::new();
-            krate.items = ThinVec::new();
-            Features::default()
-        }
-        Some(attrs) => {
-            krate.attrs = attrs;
-            let features = get_features(sess, &krate.attrs);
-            if err_count == diag.err_count() {
-                // Avoid reconfiguring malformed `cfg_attr`s.
-                strip_unconfigured.features = Some(&features);
-                // Run configuration again, this time with features available
-                // so that we can perform feature-gating.
-                strip_unconfigured.configure_krate_attrs(unconfigured_attrs);
-            }
-            features
-        }
+pub fn pre_configure_attrs(sess: &Session, attrs: &[Attribute]) -> ast::AttrVec {
+    let strip_unconfigured = StripUnconfigured {
+        sess,
+        features: None,
+        config_tokens: false,
+        lint_node_id: ast::CRATE_NODE_ID,
     };
-    (krate, features)
+    let attrs: ast::AttrVec =
+        attrs.iter().flat_map(|attr| strip_unconfigured.process_cfg_attr(attr)).collect();
+    if strip_unconfigured.in_cfg(&attrs) { attrs } else { ast::AttrVec::new() }
 }
 
 #[macro_export]
@@ -254,11 +230,6 @@ impl<'a> StripUnconfigured<'a> {
         }
     }
 
-    fn configure_krate_attrs(&self, mut attrs: ast::AttrVec) -> Option<ast::AttrVec> {
-        attrs.flat_map_in_place(|attr| self.process_cfg_attr(attr));
-        self.in_cfg(&attrs).then_some(attrs)
-    }
-
     /// Performs cfg-expansion on `stream`, producing a new `AttrTokenStream`.
     /// This is only used during the invocation of `derive` proc-macros,
     /// which require that we cfg-expand their entire input.
@@ -281,7 +252,7 @@ impl<'a> StripUnconfigured<'a> {
             .iter()
             .flat_map(|tree| match tree.clone() {
                 AttrTokenTree::Attributes(mut data) => {
-                    data.attrs.flat_map_in_place(|attr| self.process_cfg_attr(attr));
+                    data.attrs.flat_map_in_place(|attr| self.process_cfg_attr(&attr));
 
                     if self.in_cfg(&data.attrs) {
                         data.tokens = LazyAttrTokenStream::new(
@@ -319,12 +290,16 @@ impl<'a> StripUnconfigured<'a> {
     /// the syntax of any `cfg_attr` is incorrect.
     fn process_cfg_attrs<T: HasAttrs>(&self, node: &mut T) {
         node.visit_attrs(|attrs| {
-            attrs.flat_map_in_place(|attr| self.process_cfg_attr(attr));
+            attrs.flat_map_in_place(|attr| self.process_cfg_attr(&attr));
         });
     }
 
-    fn process_cfg_attr(&self, attr: Attribute) -> Vec<Attribute> {
-        if attr.has_name(sym::cfg_attr) { self.expand_cfg_attr(attr, true) } else { vec![attr] }
+    fn process_cfg_attr(&self, attr: &Attribute) -> Vec<Attribute> {
+        if attr.has_name(sym::cfg_attr) {
+            self.expand_cfg_attr(attr, true)
+        } else {
+            vec![attr.clone()]
+        }
     }
 
     /// Parse and expand a single `cfg_attr` attribute into a list of attributes
@@ -334,9 +309,9 @@ impl<'a> StripUnconfigured<'a> {
     /// Gives a compiler warning when the `cfg_attr` contains no attributes and
     /// is in the original source file. Gives a compiler error if the syntax of
     /// the attribute is incorrect.
-    pub(crate) fn expand_cfg_attr(&self, attr: Attribute, recursive: bool) -> Vec<Attribute> {
+    pub(crate) fn expand_cfg_attr(&self, attr: &Attribute, recursive: bool) -> Vec<Attribute> {
         let Some((cfg_predicate, expanded_attrs)) =
-            rustc_parse::parse_cfg_attr(&attr, &self.sess.parse_sess) else {
+            rustc_parse::parse_cfg_attr(attr, &self.sess.parse_sess) else {
                 return vec![];
             };
 
@@ -365,10 +340,10 @@ impl<'a> StripUnconfigured<'a> {
             //  `#[cfg_attr(false, cfg_attr(true, some_attr))]`.
             expanded_attrs
                 .into_iter()
-                .flat_map(|item| self.process_cfg_attr(self.expand_cfg_attr_item(&attr, item)))
+                .flat_map(|item| self.process_cfg_attr(&self.expand_cfg_attr_item(attr, item)))
                 .collect()
         } else {
-            expanded_attrs.into_iter().map(|item| self.expand_cfg_attr_item(&attr, item)).collect()
+            expanded_attrs.into_iter().map(|item| self.expand_cfg_attr_item(attr, item)).collect()
         }
     }