Auto merge of #64478 - Centril:rollup-bnt51w1, r=Centril

Rollup of 5 pull requests

Successful merges:

 - #64457 (def_collector: Do not ICE on attributes on unnamed fields)
 - #64463 (resolve: Tweak some expected/found wording)
 - #64471 (Warn on no_start, crate_id attribute use)
 - #64473 (Use try_fold instead of manually carrying an accumulator)
 - #64475 (simplify the initialization)

Failed merges:

r? @ghost

Author: bors

src/librustc/hir/map/def_collector.rs

@@ -31,7 +31,7 @@ impl<'a> DefCollector<'a> {
         self.definitions.create_def_with_parent(parent_def, node_id, data, self.expansion, span)
     }
 
-    pub fn with_parent<F: FnOnce(&mut Self)>(&mut self, parent_def: DefIndex, f: F) {
+    fn with_parent<F: FnOnce(&mut Self)>(&mut self, parent_def: DefIndex, f: F) {
         let orig_parent_def = std::mem::replace(&mut self.parent_def, parent_def);
         f(self);
         self.parent_def = orig_parent_def;
@@ -74,6 +74,22 @@ impl<'a> DefCollector<'a> {
         })
     }
 
+    fn collect_field(&mut self, field: &'a StructField, index: Option<usize>) {
+        if field.is_placeholder {
+            self.visit_macro_invoc(field.id);
+        } else {
+            let name = field.ident.map(|ident| ident.name)
+                .or_else(|| index.map(sym::integer))
+                .unwrap_or_else(|| {
+                    let node_id = NodeId::placeholder_from_expn_id(self.expansion);
+                    sym::integer(self.definitions.placeholder_field_indices[&node_id])
+                })
+                .as_interned_str();
+            let def = self.create_def(field.id, DefPathData::ValueNs(name), field.span);
+            self.with_parent(def, |this| visit::walk_struct_field(this, field));
+        }
+    }
+
     pub fn visit_macro_invoc(&mut self, id: NodeId) {
         self.definitions.set_invocation_parent(id.placeholder_to_expn_id(), self.parent_def);
     }
@@ -170,17 +186,14 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
     }
 
     fn visit_variant_data(&mut self, data: &'a VariantData) {
+        // The assumption here is that non-`cfg` macro expansion cannot change field indices.
+        // It currently holds because only inert attributes are accepted on fields,
+        // and every such attribute expands into a single field after it's resolved.
         for (index, field) in data.fields().iter().enumerate() {
-            if field.is_placeholder {
-                self.visit_macro_invoc(field.id);
-                continue;
+            self.collect_field(field, Some(index));
+            if field.is_placeholder && field.ident.is_none() {
+                self.definitions.placeholder_field_indices.insert(field.id, index);
             }
-            let name = field.ident.map(|ident| ident.name)
-                .unwrap_or_else(|| sym::integer(index));
-            let def = self.create_def(field.id,
-                                      DefPathData::ValueNs(name.as_interned_str()),
-                                      field.span);
-            self.with_parent(def, |this| visit::walk_struct_field(this, field));
         }
     }
 
@@ -338,16 +351,9 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
         }
     }
 
-    fn visit_struct_field(&mut self, sf: &'a StructField) {
-        if sf.is_placeholder {
-            self.visit_macro_invoc(sf.id)
-        } else {
-            let name = sf.ident.map(|ident| ident.name)
-                .unwrap_or_else(|| panic!("don't know the field number in this context"));
-            let def = self.create_def(sf.id,
-                                        DefPathData::ValueNs(name.as_interned_str()),
-                                        sf.span);
-            self.with_parent(def, |this| visit::walk_struct_field(this, sf));
-        }
+    // This method is called only when we are visiting an individual field
+    // after expanding an attribute on it.
+    fn visit_struct_field(&mut self, field: &'a StructField) {
+        self.collect_field(field, None);
     }
 }

src/librustc/hir/map/definitions.rs

@@ -104,6 +104,8 @@ pub struct Definitions {
     /// When collecting definitions from an AST fragment produced by a macro invocation `ExpnId`
     /// we know what parent node that fragment should be attached to thanks to this table.
     invocation_parents: FxHashMap<ExpnId, DefIndex>,
+    /// Indices of unnamed struct or variant fields with unresolved attributes.
+    pub(super) placeholder_field_indices: NodeMap<usize>,
 }
 
 /// A unique identifier that we can use to lookup a definition

src/librustc_lint/builtin.rs

@@ -669,6 +669,22 @@ impl DeprecatedAttr {
     }
 }
 
+fn lint_deprecated_attr(
+    cx: &EarlyContext<'_>,
+    attr: &ast::Attribute,
+    msg: &str,
+    suggestion: Option<&str>,
+) {
+    cx.struct_span_lint(DEPRECATED, attr.span, &msg)
+        .span_suggestion_short(
+            attr.span,
+            suggestion.unwrap_or("remove this attribute"),
+            String::new(),
+            Applicability::MachineApplicable
+        )
+        .emit();
+}
+
 impl EarlyLintPass for DeprecatedAttr {
     fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
         for &&(n, _, _, ref g) in &self.depr_attrs {
@@ -679,18 +695,15 @@ impl EarlyLintPass for DeprecatedAttr {
                                              _) = g {
                     let msg = format!("use of deprecated attribute `{}`: {}. See {}",
                                       name, reason, link);
-                    let mut err = cx.struct_span_lint(DEPRECATED, attr.span, &msg);
-                    err.span_suggestion_short(
-                        attr.span,
-                        suggestion.unwrap_or("remove this attribute"),
-                        String::new(),
-                        Applicability::MachineApplicable
-                    );
-                    err.emit();
+                    lint_deprecated_attr(cx, attr, &msg, suggestion);
                 }
                 return;
             }
         }
+        if attr.check_name(sym::no_start) || attr.check_name(sym::crate_id) {
+            let msg = format!("use of deprecated attribute `{}`: no longer used.", attr.path);
+            lint_deprecated_attr(cx, attr, &msg, None);
+        }
     }
 }
 

src/librustc_mir/interpret/operand.rs

@@ -477,7 +477,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     ) -> InterpResult<'tcx, OpTy<'tcx, M::PointerTag>> {
         use rustc::mir::PlaceBase;
 
-        let mut op = match &place.base {
+        let base_op = match &place.base {
             PlaceBase::Local(mir::RETURN_PLACE) =>
                 throw_unsup!(ReadFromReturnPointer),
             PlaceBase::Local(local) => {
@@ -497,9 +497,10 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             }
         };
 
-        for elem in place.projection.iter() {
-            op = self.operand_projection(op, elem)?
-        }
+        let op = place.projection.iter().try_fold(
+            base_op,
+            |op, elem| self.operand_projection(op, elem)
+        )?;
 
         trace!("eval_place_to_op: got {:?}", *op);
         Ok(op)

src/librustc_resolve/macros.rs

@@ -237,7 +237,8 @@ impl<'a> base::Resolver for Resolver<'a> {
                 if let Res::Def(..) = res {
                     self.session.span_err(
                         span,
-                        "expected an inert attribute, found an attribute macro"
+                        &format!("expected an inert attribute, found {} {}",
+                                 res.article(), res.descr()),
                     );
                     return Ok(InvocationRes::Single(self.dummy_ext(kind)));
                 }
@@ -322,7 +323,7 @@ impl<'a> Resolver<'a> {
         self.check_stability_and_deprecation(&ext, path);
 
         Ok(if ext.macro_kind() != kind {
-            let expected = if kind == MacroKind::Attr { "attribute" } else  { kind.descr() };
+            let expected = if kind == MacroKind::Attr { "attribute" } else { kind.descr() };
             let msg = format!("expected {}, found {} `{}`", expected, res.descr(), path);
             self.session.struct_span_err(path.span, &msg)
                         .span_label(path.span, format!("not {} {}", kind.article(), expected))

src/librustc_typeck/check/mod.rs

@@ -400,7 +400,7 @@ pub struct UnsafetyState {
 
 impl UnsafetyState {
     pub fn function(unsafety: hir::Unsafety, def: hir::HirId) -> UnsafetyState {
-        UnsafetyState { def: def, unsafety: unsafety, unsafe_push_count: 0, from_fn: true }
+        UnsafetyState { def, unsafety, unsafe_push_count: 0, from_fn: true }
     }
 
     pub fn recurse(&mut self, blk: &hir::Block) -> UnsafetyState {

src/test/ui/attributes/item-attributes.rs

@@ -11,8 +11,6 @@
 #![rustc_dummy]
 #![rustc_dummy(attr5)]
 
-#![crate_id="foobar#0.1"]
-
 // These are attributes of the following mod
 #[rustc_dummy = "val"]
 #[rustc_dummy = "val"]

src/test/ui/attributes/unnamed-field-attributes.rs

@@ -0,0 +1,9 @@
+// check-pass
+
+struct S(
+    #[rustfmt::skip] u8,
+    u16,
+    #[rustfmt::skip] u32,
+);
+
+fn main() {}

src/test/ui/feature-gate/issue-43106-gating-of-builtin-attrs.rs

@@ -84,12 +84,12 @@
 #![crate_name = "0900"]
 #![crate_type = "bin"] // cannot pass "0800" here
 
-// For #![crate_id], see issue #43142. (I cannot bear to enshrine current behavior in a test)
+#![crate_id = "10"] //~ WARN use of deprecated attribute
 
 // FIXME(#44232) we should warn that this isn't used.
 #![feature(rust1)]
 
-// For #![no_start], see issue #43144. (I cannot bear to enshrine current behavior in a test)
+#![no_start] //~ WARN use of deprecated attribute
 
 // (cannot easily gating state of crate-level #[no_main]; but non crate-level is below at "0400")
 #![no_builtins]

src/test/ui/feature-gate/issue-43106-gating-of-builtin-attrs.stderr

@@ -186,6 +186,20 @@ LL |     mod inner { #![macro_escape] }
    |
    = help: consider an outer attribute, `#[macro_use]` mod ...
 
+warning: use of deprecated attribute `crate_id`: no longer used.
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:87:1
+   |
+LL | #![crate_id = "10"]
+   | ^^^^^^^^^^^^^^^^^^^ help: remove this attribute
+   |
+   = note: `#[warn(deprecated)]` on by default
+
+warning: use of deprecated attribute `no_start`: no longer used.
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:92:1
+   |
+LL | #![no_start]
+   | ^^^^^^^^^^^^ help: remove this attribute
+
 warning: the feature `rust1` has been stable since 1.0.0 and no longer requires an attribute to enable
   --> $DIR/issue-43106-gating-of-builtin-attrs.rs:90:12
    |