resolve: allow super in module in block to refer to block items

compiler/rustc_resolve/src/imports.rs

@@ -4,10 +4,10 @@ use crate::diagnostics::Suggestion;
 use crate::Determinacy::{self, *};
 use crate::Namespace::{self, MacroNS, TypeNS};
 use crate::{module_to_string, names_to_string};
+use crate::{AllowResolveBlocks, BindingKey, ModuleKind, ResolutionError, Resolver, Segment};
 use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind};
-use crate::{BindingKey, ModuleKind, ResolutionError, Resolver, Segment};
 use crate::{CrateLint, Module, ModuleOrUniformRoot, ParentScope, PerNS, ScopeSet, Weak};
-use crate::{NameBinding, NameBindingKind, PathResult, PrivacyError, ToNameBinding};
+use crate::{ModuleData, NameBinding, NameBindingKind, PathResult, PrivacyError, ToNameBinding};
 
 use rustc_ast::unwrap_or;
 use rustc_ast::NodeId;
@@ -777,13 +777,15 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
             // For better failure detection, pretend that the import will
             // not define any names while resolving its module path.
             let orig_vis = import.vis.replace(ty::Visibility::Invisible);
-            let path_res = self.r.resolve_path(
+            let path_res = self.r.resolve_path_with_ribs(
                 &import.module_path,
                 None,
                 &import.parent_scope,
                 false,
                 import.span,
                 import.crate_lint(),
+                None,
+                AllowResolveBlocks::Yes,
             );
             import.vis.set(orig_vis);
 
@@ -818,16 +820,37 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
                     // For better failure detection, pretend that the import will
                     // not define any names while resolving its module path.
                     let orig_vis = import.vis.replace(ty::Visibility::Invisible);
-                    let binding = this.resolve_ident_in_module(
+                    let mut binding = this.resolve_ident_in_module(
                         module,
                         source,
                         ns,
                         &import.parent_scope,
                         false,
                         import.span,
                     );
-                    import.vis.set(orig_vis);
 
+                    let mut module = module;
+                    while binding.is_err() {
+                        match module {
+                            ModuleOrUniformRoot::Module(m @ ModuleData { parent: Some(p), .. })
+                                if m.is_block() =>
+                            {
+                                // item not found in opaque block module; try inside module containing the block
+                                module = ModuleOrUniformRoot::Module(*p);
+                                binding = this.resolve_ident_in_module(
+                                    module,
+                                    source,
+                                    ns,
+                                    &import.parent_scope,
+                                    false,
+                                    import.span,
+                                );
+                            }
+                            _ => break,
+                        }
+                    }
+
+                    import.vis.set(orig_vis);
                     source_bindings[ns].set(binding);
                 } else {
                     return;
@@ -878,13 +901,15 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
             _ => None,
         };
         let prev_ambiguity_errors_len = self.r.ambiguity_errors.len();
-        let path_res = self.r.resolve_path(
+        let path_res = self.r.resolve_path_with_ribs(
             &import.module_path,
             None,
             &import.parent_scope,
             true,
             import.span,
             import.crate_lint(),
+            None,
+            AllowResolveBlocks::Yes,
         );
         let no_ambiguity = self.r.ambiguity_errors.len() == prev_ambiguity_errors_len;
         if let Some(orig_unusable_binding) = orig_unusable_binding {
@@ -1010,14 +1035,36 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
                 let orig_unusable_binding =
                     mem::replace(&mut this.unusable_binding, target_bindings[ns].get());
                 let orig_last_import_segment = mem::replace(&mut this.last_import_segment, true);
-                let binding = this.resolve_ident_in_module(
+                let mut binding = this.resolve_ident_in_module(
                     module,
                     ident,
                     ns,
                     &import.parent_scope,
                     true,
                     import.span,
                 );
+
+                let mut module = module;
+                while binding.is_err() {
+                    match module {
+                        ModuleOrUniformRoot::Module(m @ ModuleData { parent: Some(p), .. })
+                            if m.is_block() =>
+                        {
+                            // item not found in opaque block module; try inside module containing the block
+                            module = ModuleOrUniformRoot::Module(*p);
+                            binding = this.resolve_ident_in_module(
+                                module,
+                                ident,
+                                ns,
+                                &import.parent_scope,
+                                false,
+                                import.span,
+                            );
+                        }
+                        _ => break,
+                    }
+                }
+
                 this.last_import_segment = orig_last_import_segment;
                 this.unusable_binding = orig_unusable_binding;
                 import.vis.set(orig_vis);
@@ -1323,7 +1370,7 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
     }
 
     fn resolve_glob_import(&mut self, import: &'b Import<'b>) {
-        let module = match import.imported_module.get().unwrap() {
+        let mut module = match import.imported_module.get().unwrap() {
             ModuleOrUniformRoot::Module(module) => module,
             _ => {
                 self.r.session.span_err(import.span, "cannot glob-import all possible crates");
@@ -1346,7 +1393,7 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
 
         // Ensure that `resolutions` isn't borrowed during `try_define`,
         // since it might get updated via a glob cycle.
-        let bindings = self
+        let mut bindings = self
             .r
             .resolutions(module)
             .borrow()
@@ -1355,6 +1402,53 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
                 resolution.borrow().binding().map(|binding| (*key, binding))
             })
             .collect::<Vec<_>>();
+
+        if module.is_block() {
+            // Glob imports should see "through" an opaque module.
+            // Prefer items in the opaque module to items in the parent.
+
+            let mut imported_items = FxHashSet::default();
+
+            while module.is_block() && module.parent.is_some() {
+                // import these bindings
+                for (mut key, binding) in bindings {
+                    let scope =
+                        match key.ident.span.reverse_glob_adjust(module.expansion, import.span) {
+                            Some(Some(def)) => self.r.macro_def_scope(def),
+                            Some(None) => import.parent_scope.module,
+                            None => continue,
+                        };
+                    if self.r.is_accessible_from(binding.vis, scope) {
+                        let imported_binding = self.r.import(binding, import);
+                        let _ =
+                            self.r.try_define(import.parent_scope.module, key, imported_binding);
+                        imported_items.insert(key);
+                    }
+                }
+
+                // This was an opaque module; repeat with parent module.
+                module = module.parent.unwrap();
+
+                // Add to module's glob_importers
+                module.glob_importers.borrow_mut().push(import);
+
+                // Ensure that `resolutions` isn't borrowed during `try_define`,
+                // since it might get updated via a glob cycle.
+                bindings = self
+                    .r
+                    .resolutions(module)
+                    .borrow()
+                    .iter()
+                    .filter_map(|(key, resolution)| {
+                        if imported_items.contains(key) {
+                            return None;
+                        }
+                        resolution.borrow().binding().map(|binding| (*key, binding))
+                    })
+                    .collect::<Vec<_>>();
+            }
+        }
+
         for (mut key, binding) in bindings {
             let scope = match key.ident.span.reverse_glob_adjust(module.expansion, import.span) {
                 Some(Some(def)) => self.r.macro_def_scope(def),

compiler/rustc_resolve/src/late.rs

@@ -747,6 +747,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
             path_span,
             crate_lint,
             Some(&self.ribs),
+            crate::AllowResolveBlocks::No,
         )
     }
 

compiler/rustc_resolve/src/lib.rs

@@ -12,6 +12,7 @@
 #![feature(box_patterns)]
 #![feature(bool_to_option)]
 #![feature(control_flow_enum)]
+#![feature(bindings_after_at)]
 #![feature(crate_visibility_modifier)]
 #![feature(format_args_capture)]
 #![feature(nll)]
@@ -597,6 +598,10 @@ impl<'a> ModuleData<'a> {
         matches!(self.kind, ModuleKind::Def(DefKind::Trait, _, _))
     }
 
+    fn is_block(&self) -> bool {
+        matches!(self.kind, ModuleKind::Block(_))
+    }
+
     fn nearest_item_scope(&'a self) -> Module<'a> {
         match self.kind {
             ModuleKind::Def(DefKind::Enum | DefKind::Trait, ..) => {
@@ -839,6 +844,13 @@ enum BuiltinMacroState {
     AlreadySeen(Span),
 }
 
+/// Whether resolve_path_with_ribs may resolve to anonymous block modules
+#[derive(Copy, Clone, Debug)]
+enum AllowResolveBlocks {
+    No,
+    Yes,
+}
+
 /// The main resolver class.
 ///
 /// This is the visitor that walks the whole crate.
@@ -2177,6 +2189,7 @@ impl<'a> Resolver<'a> {
             path_span,
             crate_lint,
             None,
+            AllowResolveBlocks::No,
         )
     }
 
@@ -2189,6 +2202,7 @@ impl<'a> Resolver<'a> {
         path_span: Span,
         crate_lint: CrateLint,
         ribs: Option<&PerNS<Vec<Rib<'a>>>>,
+        resolve_opaque: AllowResolveBlocks,
     ) -> PathResult<'a> {
         let mut module = None;
         let mut allow_super = true;
@@ -2231,9 +2245,11 @@ impl<'a> Resolver<'a> {
                     };
                     if let Some(self_module) = self_module {
                         if let Some(parent) = self_module.parent {
-                            module = Some(ModuleOrUniformRoot::Module(
-                                self.resolve_self(&mut ctxt, parent),
-                            ));
+                            let resolved = match (resolve_opaque, &parent.kind) {
+                                (AllowResolveBlocks::Yes, ModuleKind::Block(_)) => parent,
+                                _ => self.resolve_self(&mut ctxt, parent),
+                            };
+                            module = Some(ModuleOrUniformRoot::Module(resolved));
                             continue;
                         }
                     }

src/test/rustdoc/mod-in-doctest.rs

@@ -0,0 +1,13 @@
+// compile-flags:--test
+// edition:2018
+
+//! ```
+//! fn foo() {}
+//!
+//! mod bar {
+//!     use super::foo;
+//!     fn bar() {
+//!         foo()
+//!     }
+//! }
+//! ```

src/test/ui/resolve/module-in-block-build-pass.rs

@@ -0,0 +1,98 @@
+// build-pass
+
+const CONST: &str = "OUTER";
+fn bar() -> &'static str { "outer" }
+
+fn module_in_function_use_super() {
+    mod inner {
+        use super::{bar, CONST};
+        fn call_bar() {
+            bar();
+        }
+
+        fn get_const() -> &'static str {
+            CONST
+        }
+    }
+}
+
+fn module_in_function_resolve_super() {
+    mod inner {
+        fn call_bar() {
+            super::bar();
+        }
+
+        fn get_const() -> &'static str {
+            super::CONST
+        }
+    }
+}
+
+
+fn module_in_function_use_super_glob() {
+    mod inner {
+        use super::*;
+        fn call_bar() {
+            bar();
+        }
+
+        fn get_const() -> &'static str {
+            CONST
+        }
+    }
+}
+
+fn module_in_block_use_super() {
+    {
+        mod inner {
+            use super::{bar, CONST};
+            fn call_bar() {
+                bar();
+            }
+
+            fn get_const() -> &'static str {
+                CONST
+            }
+        }
+    }
+}
+
+fn module_in_block_resolve_super() {
+    {
+        mod inner {
+            fn call_bar() {
+                super::bar();
+            }
+
+            fn get_const() -> &'static str {
+                super::CONST
+            }
+        }
+    }
+}
+
+
+fn module_in_block_use_super_glob() {
+    {
+        mod inner {
+            use super::*;
+            fn call_bar() {
+                bar();
+            }
+
+            fn get_const() -> &'static str {
+                CONST
+            }
+        }
+    }
+}
+
+fn main() {
+    module_in_function_use_super();
+    module_in_function_resolve_super();
+    module_in_function_use_super_glob();
+
+    module_in_block_use_super();
+    module_in_block_resolve_super();
+    module_in_block_use_super_glob();
+}

src/test/ui/resolve/module-in-block-compile-fail.rs

@@ -0,0 +1,12 @@
+fn module_in_function_cannot_access_variables() {
+    let x: i32 = 5;
+
+    mod inner {
+        use super::x;  //~ ERROR unresolved import `super::x`
+        fn get_x() -> i32 {
+            x
+        }
+    }
+}
+
+fn main() { }