7 files changed, 113 insertions, 12 deletions

diff --git a/crates/hir_def/src/body.rs b/crates/hir_def/src/body.rs
index 8360426f1..98b485b60 100644
--- a/crates/hir_def/src/body.rs
+++ b/crates/hir_def/src/body.rs
@@ -21,8 +21,6 @@ use profile::Count;
 use rustc_hash::FxHashMap;
 use syntax::{ast, AstNode, AstPtr};
 
-pub use lower::LowerCtx;
-
 use crate::{
     attr::{Attrs, RawAttrs},
     db::DefDatabase,
@@ -35,6 +33,8 @@ use crate::{
     UnresolvedMacro,
 };
 
+pub use lower::LowerCtx;
+
 /// A subset of Expander that only deals with cfg attributes. We only need it to
 /// avoid cyclic queries in crate def map during enum processing.
 #[derive(Debug)]
diff --git a/crates/hir_def/src/body/lower.rs b/crates/hir_def/src/body/lower.rs
index 9f278d35b..2a7e0205f 100644
--- a/crates/hir_def/src/body/lower.rs
+++ b/crates/hir_def/src/body/lower.rs
@@ -1006,23 +1006,27 @@ impl From<ast::BinOp> for BinaryOp {
 impl From<ast::LiteralKind> for Literal {
     fn from(ast_lit_kind: ast::LiteralKind) -> Self {
         match ast_lit_kind {
+            // FIXME: these should have actual values filled in, but unsure on perf impact
             LiteralKind::IntNumber(lit) => {
                 if let builtin @ Some(_) = lit.suffix().and_then(BuiltinFloat::from_suffix) {
                     return Literal::Float(Default::default(), builtin);
                 } else if let builtin @ Some(_) =
                     lit.suffix().and_then(|it| BuiltinInt::from_suffix(&it))
                 {
-                    Literal::Int(Default::default(), builtin)
+                    Literal::Int(lit.value().unwrap_or(0) as i128, builtin)
                 } else {
                     let builtin = lit.suffix().and_then(|it| BuiltinUint::from_suffix(&it));
-                    Literal::Uint(Default::default(), builtin)
+                    Literal::Uint(lit.value().unwrap_or(0), builtin)
                 }
             }
             LiteralKind::FloatNumber(lit) => {
                 let ty = lit.suffix().and_then(|it| BuiltinFloat::from_suffix(&it));
                 Literal::Float(Default::default(), ty)
             }
-            LiteralKind::ByteString(_) => Literal::ByteString(Default::default()),
+            LiteralKind::ByteString(bs) => {
+                let text = bs.value().map(Vec::from).unwrap_or_else(Default::default);
+                Literal::ByteString(text)
+            }
             LiteralKind::String(_) => Literal::String(Default::default()),
             LiteralKind::Byte => Literal::Uint(Default::default(), Some(BuiltinUint::U8)),
             LiteralKind::Bool(val) => Literal::Bool(val),
diff --git a/crates/hir_def/src/expr.rs b/crates/hir_def/src/expr.rs
index 0c3b41080..2ba619d23 100644
--- a/crates/hir_def/src/expr.rs
+++ b/crates/hir_def/src/expr.rs
@@ -43,8 +43,8 @@ pub enum Literal {
     ByteString(Vec<u8>),
     Char(char),
     Bool(bool),
-    Int(u64, Option<BuiltinInt>),
-    Uint(u64, Option<BuiltinUint>),
+    Int(i128, Option<BuiltinInt>),
+    Uint(u128, Option<BuiltinUint>),
     Float(u64, Option<BuiltinFloat>), // FIXME: f64 is not Eq
 }
 
diff --git a/crates/hir_def/src/find_path.rs b/crates/hir_def/src/find_path.rs
index 858e88038..ee52794aa 100644
--- a/crates/hir_def/src/find_path.rs
+++ b/crates/hir_def/src/find_path.rs
@@ -5,10 +5,10 @@ use std::iter;
 use hir_expand::name::{known, AsName, Name};
 use rustc_hash::FxHashSet;
 
-use crate::nameres::DefMap;
 use crate::{
     db::DefDatabase,
     item_scope::ItemInNs,
+    nameres::DefMap,
     path::{ModPath, PathKind},
     visibility::Visibility,
     ModuleDefId, ModuleId,
@@ -134,7 +134,16 @@ fn find_path_inner(
     for (name, def_id) in root_def_map.extern_prelude() {
         if item == ItemInNs::Types(*def_id) {
             let name = scope_name.unwrap_or_else(|| name.clone());
-            return Some(ModPath::from_segments(PathKind::Plain, vec![name]));
+
+            let name_already_occupied_in_type_ns = def_map
+                .with_ancestor_maps(db, from.local_id, &mut |def_map, local_id| {
+                    def_map[local_id].scope.get(&name).take_types().filter(|&id| id != *def_id)
+                })
+                .is_some();
+            return Some(ModPath::from_segments(
+                if name_already_occupied_in_type_ns { PathKind::Abs } else { PathKind::Plain },
+                vec![name],
+            ));
         }
     }
 
diff --git a/crates/hir_def/src/nameres/collector.rs b/crates/hir_def/src/nameres/collector.rs
index a68674c10..d4840be2f 100644
--- a/crates/hir_def/src/nameres/collector.rs
+++ b/crates/hir_def/src/nameres/collector.rs
@@ -481,6 +481,11 @@ impl DefCollector<'_> {
         let res = self.def_map.resolve_name_in_extern_prelude(self.db, &extern_crate.name);
 
         if let Some(ModuleDefId::ModuleId(m)) = res.take_types() {
+            if m == self.def_map.module_id(current_module_id) {
+                cov_mark::hit!(ignore_macro_use_extern_crate_self);
+                return;
+            }
+
             cov_mark::hit!(macro_rules_from_other_crates_are_visible_with_macro_use);
             self.import_all_macros_exported(current_module_id, m.krate);
         }
diff --git a/crates/hir_def/src/nameres/tests.rs b/crates/hir_def/src/nameres/tests.rs
index 4f2e7a2f9..9f652731d 100644
--- a/crates/hir_def/src/nameres/tests.rs
+++ b/crates/hir_def/src/nameres/tests.rs
@@ -411,6 +411,22 @@ struct Arc;
 }
 
 #[test]
+fn macro_use_extern_crate_self() {
+    cov_mark::check!(ignore_macro_use_extern_crate_self);
+    check(
+        r#"
+//- /main.rs crate:main
+#[macro_use]
+extern crate self as bla;
+"#,
+        expect![[r#"
+            crate
+            bla: t
+        "#]],
+    );
+}
+
+#[test]
 fn reexport_across_crates() {
     check(
         r#"
diff --git a/crates/hir_def/src/type_ref.rs b/crates/hir_def/src/type_ref.rs
index ea29da5da..9e44547cb 100644
--- a/crates/hir_def/src/type_ref.rs
+++ b/crates/hir_def/src/type_ref.rs
@@ -2,6 +2,7 @@
 //! be directly created from an ast::TypeRef, without further queries.
 
 use hir_expand::{name::Name, AstId, InFile};
+use std::convert::TryInto;
 use syntax::ast;
 
 use crate::{body::LowerCtx, path::Path};
@@ -79,7 +80,9 @@ pub enum TypeRef {
     Path(Path),
     RawPtr(Box<TypeRef>, Mutability),
     Reference(Box<TypeRef>, Option<LifetimeRef>, Mutability),
-    Array(Box<TypeRef> /*, Expr*/),
+    // FIXME: for full const generics, the latter element (length) here is going to have to be an
+    // expression that is further lowered later in hir_ty.
+    Array(Box<TypeRef>, ConstScalar),
     Slice(Box<TypeRef>),
     /// A fn pointer. Last element of the vector is the return type.
     Fn(Vec<TypeRef>, bool /*varargs*/),
@@ -140,7 +143,16 @@ impl TypeRef {
                 TypeRef::RawPtr(Box::new(inner_ty), mutability)
             }
             ast::Type::ArrayType(inner) => {
-                TypeRef::Array(Box::new(TypeRef::from_ast_opt(&ctx, inner.ty())))
+                // FIXME: This is a hack. We should probably reuse the machinery of
+                // `hir_def::body::lower` to lower this into an `Expr` and then evaluate it at the
+                // `hir_ty` level, which would allow knowing the type of:
+                // let v: [u8; 2 + 2] = [0u8; 4];
+                let len = inner
+                    .expr()
+                    .map(ConstScalar::usize_from_literal_expr)
+                    .unwrap_or(ConstScalar::Unknown);
+
+                TypeRef::Array(Box::new(TypeRef::from_ast_opt(&ctx, inner.ty())), len)
             }
             ast::Type::SliceType(inner) => {
                 TypeRef::Slice(Box::new(TypeRef::from_ast_opt(&ctx, inner.ty())))
@@ -212,7 +224,7 @@ impl TypeRef {
                 }
                 TypeRef::RawPtr(type_ref, _)
                 | TypeRef::Reference(type_ref, ..)
-                | TypeRef::Array(type_ref)
+                | TypeRef::Array(type_ref, _)
                 | TypeRef::Slice(type_ref) => go(&type_ref, f),
                 TypeRef::ImplTrait(bounds) | TypeRef::DynTrait(bounds) => {
                     for bound in bounds {
@@ -298,3 +310,58 @@ impl TypeBound {
         }
     }
 }
+
+/// A concrete constant value
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum ConstScalar {
+    // for now, we only support the trivial case of constant evaluating the length of an array
+    // Note that this is u64 because the target usize may be bigger than our usize
+    Usize(u64),
+
+    /// Case of an unknown value that rustc might know but we don't
+    // FIXME: this is a hack to get around chalk not being able to represent unevaluatable
+    // constants
+    // https://github.com/rust-analyzer/rust-analyzer/pull/8813#issuecomment-840679177
+    // https://rust-lang.zulipchat.com/#narrow/stream/144729-wg-traits/topic/Handling.20non.20evaluatable.20constants'.20equality/near/238386348
+    Unknown,
+}
+
+impl std::fmt::Display for ConstScalar {
+    fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
+        match self {
+            ConstScalar::Usize(us) => write!(fmt, "{}", us),
+            ConstScalar::Unknown => write!(fmt, "_"),
+        }
+    }
+}
+
+impl ConstScalar {
+    /// Gets a target usize out of the ConstScalar
+    pub fn as_usize(&self) -> Option<u64> {
+        match self {
+            &ConstScalar::Usize(us) => Some(us),
+            _ => None,
+        }
+    }
+
+    // FIXME: as per the comments on `TypeRef::Array`, this evaluation should not happen at this
+    // parse stage.
+    fn usize_from_literal_expr(expr: ast::Expr) -> ConstScalar {
+        match expr {
+            ast::Expr::Literal(lit) => {
+                let lkind = lit.kind();
+                match lkind {
+                    ast::LiteralKind::IntNumber(num)
+                        if num.suffix() == None || num.suffix() == Some("usize") =>
+                    {
+                        num.value().and_then(|v| v.try_into().ok())
+                    }
+                    _ => None,
+                }
+            }
+            _ => None,
+        }
+        .map(ConstScalar::Usize)
+        .unwrap_or(ConstScalar::Unknown)
+    }
+}