Rollup merge of #153540 - scrabsha:sasha/drop-derive-helpers, r=jdonszelmann

drop derive helpers during attribute parsing

Author: JonathanBrouwer

compiler/rustc_attr_parsing/src/errors.rs

@@ -0,0 +1,35 @@
+use rustc_errors::MultiSpan;
+use rustc_macros::{Diagnostic, Subdiagnostic};
+use rustc_span::{Span, Symbol};
+
+#[derive(Diagnostic)]
+#[diag("`{$name}` attribute cannot be used at crate level")]
+pub(crate) struct InvalidAttrAtCrateLevel {
+    #[primary_span]
+    pub span: Span,
+    #[suggestion(
+        "perhaps you meant to use an outer attribute",
+        code = "#[",
+        applicability = "machine-applicable",
+        style = "verbose"
+    )]
+    pub pound_to_opening_bracket: Span,
+    pub name: Symbol,
+    #[subdiagnostic]
+    pub item: Option<ItemFollowingInnerAttr>,
+}
+
+#[derive(Clone, Copy, Subdiagnostic)]
+#[label("the inner attribute doesn't annotate this item")]
+pub(crate) struct ItemFollowingInnerAttr {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag("most attributes are not supported in `where` clauses")]
+#[help("only `#[cfg]` and `#[cfg_attr]` are supported")]
+pub(crate) struct UnsupportedAttributesInWhere {
+    #[primary_span]
+    pub span: MultiSpan,
+}

compiler/rustc_attr_parsing/src/interface.rs

@@ -269,6 +269,11 @@ impl<'sess, S: Stage> AttributeParser<'sess, S> {
         mut emit_lint: impl FnMut(LintId, Span, AttributeLintKind),
     ) -> Vec<Attribute> {
         let mut attributes = Vec::new();
+        // We store the attributes we intend to discard at the end of this function in order to
+        // check they are applied to the right target and error out if necessary. In practice, we
+        // end up dropping only derive attributes and derive helpers, both being fully processed
+        // at macro expansion.
+        let mut dropped_attributes = Vec::new();
         let mut attr_paths: Vec<RefPathParser<'_>> = Vec::new();
         let mut early_parsed_state = EarlyParsedState::default();
 
@@ -304,7 +309,7 @@ impl<'sess, S: Stage> AttributeParser<'sess, S> {
                         kind: DocFragmentKind::Sugared(*comment_kind),
                         span: attr_span,
                         comment: *symbol,
-                    }))
+                    }));
                 }
                 ast::AttrKind::Normal(n) => {
                     attr_paths.push(PathParser(&n.item.path));
@@ -393,29 +398,33 @@ impl<'sess, S: Stage> AttributeParser<'sess, S> {
                             Self::check_target(&accept.allowed_targets, target, &mut cx);
                         }
                     } else {
-                        // If we're here, we must be compiling a tool attribute... Or someone
-                        // forgot to parse their fancy new attribute. Let's warn them in any case.
-                        // If you are that person, and you really think your attribute should
-                        // remain unparsed, carefully read the documentation in this module and if
-                        // you still think so you can add an exception to this assertion.
-
-                        // FIXME(jdonszelmann): convert other attributes, and check with this that
-                        // we caught em all
-                        // const FIXME_TEMPORARY_ATTR_ALLOWLIST: &[Symbol] = &[sym::cfg];
-                        // assert!(
-                        //     self.tools.contains(&parts[0]) || true,
-                        //     // || FIXME_TEMPORARY_ATTR_ALLOWLIST.contains(&parts[0]),
-                        //     "attribute {path} wasn't parsed and isn't a know tool attribute",
-                        // );
-
-                        attributes.push(Attribute::Unparsed(Box::new(AttrItem {
+                        let attr = AttrItem {
                             path: attr_path.clone(),
                             args: self
                                 .lower_attr_args(n.item.args.unparsed_ref().unwrap(), lower_span),
                             id: HashIgnoredAttrId { attr_id: attr.id },
                             style: attr.style,
                             span: attr_span,
-                        })));
+                        };
+
+                        if !matches!(self.stage.should_emit(), ShouldEmit::Nothing)
+                            && target == Target::Crate
+                        {
+                            self.check_invalid_crate_level_attr_item(&attr, n.item.span());
+                        }
+
+                        let attr = Attribute::Unparsed(Box::new(attr));
+
+                        if self.tools.contains(&parts[0])
+                            // FIXME: this can be removed once #152369 has been merged.
+                            // https://github.com/rust-lang/rust/pull/152369
+                            || [sym::allow, sym::deny, sym::expect, sym::forbid, sym::warn]
+                                .contains(&parts[0])
+                        {
+                            attributes.push(attr);
+                        } else {
+                            dropped_attributes.push(attr);
+                        }
                     }
                 }
             }
@@ -431,6 +440,12 @@ impl<'sess, S: Stage> AttributeParser<'sess, S> {
             }
         }
 
+        if !matches!(self.stage.should_emit(), ShouldEmit::Nothing)
+            && target == Target::WherePredicate
+        {
+            self.check_invalid_where_predicate_attrs(attributes.iter().chain(&dropped_attributes));
+        }
+
         attributes
     }
 

compiler/rustc_attr_parsing/src/lib.rs

@@ -79,6 +79,7 @@
 // tidy-alphabetical-start
 #![feature(decl_macro)]
 #![feature(iter_intersperse)]
+#![feature(try_blocks)]
 #![recursion_limit = "256"]
 // tidy-alphabetical-end
 
@@ -99,6 +100,7 @@ mod interface;
 pub mod parser;
 
 mod early_parsed;
+mod errors;
 mod safety;
 mod session_diagnostics;
 mod target_checking;

compiler/rustc_attr_parsing/src/target_checking.rs

@@ -1,14 +1,18 @@
 use std::borrow::Cow;
 
 use rustc_ast::AttrStyle;
-use rustc_errors::DiagArgValue;
+use rustc_errors::{DiagArgValue, MultiSpan, StashKey};
 use rustc_feature::Features;
+use rustc_hir::attrs::AttributeKind;
 use rustc_hir::lints::AttributeLintKind;
-use rustc_hir::{MethodKind, Target};
-use rustc_span::sym;
+use rustc_hir::{AttrItem, Attribute, MethodKind, Target};
+use rustc_span::{BytePos, Span, Symbol, sym};
 
 use crate::AttributeParser;
 use crate::context::{AcceptContext, Stage};
+use crate::errors::{
+    InvalidAttrAtCrateLevel, ItemFollowingInnerAttr, UnsupportedAttributesInWhere,
+};
 use crate::session_diagnostics::InvalidTarget;
 use crate::target_checking::Policy::Allow;
 
@@ -96,6 +100,25 @@ impl<'sess, S: Stage> AttributeParser<'sess, S> {
             return;
         }
 
+        if matches!(cx.attr_path.segments.as_ref(), [sym::repr]) && target == Target::Crate {
+            // The allowed targets of `repr` depend on its arguments. They can't be checked using
+            // the `AttributeParser` code.
+            let span = cx.attr_span;
+            let item =
+                cx.cx.first_line_of_next_item(span).map(|span| ItemFollowingInnerAttr { span });
+
+            let pound_to_opening_bracket = cx.attr_span.until(cx.inner_span);
+
+            cx.dcx()
+                .create_err(InvalidAttrAtCrateLevel {
+                    span,
+                    pound_to_opening_bracket,
+                    name: sym::repr,
+                    item,
+                })
+                .emit();
+        }
+
         match allowed_targets.is_allowed(target) {
             AllowedResult::Allowed => {}
             AllowedResult::Warn => {
@@ -163,6 +186,113 @@ impl<'sess, S: Stage> AttributeParser<'sess, S> {
 
         cx.emit_lint(rustc_session::lint::builtin::UNUSED_ATTRIBUTES, kind, attr_span);
     }
+
+    // FIXME: Fix "Cannot determine resolution" error and remove built-in macros
+    // from this check.
+    pub(crate) fn check_invalid_crate_level_attr_item(&self, attr: &AttrItem, inner_span: Span) {
+        // Check for builtin attributes at the crate level
+        // which were unsuccessfully resolved due to cannot determine
+        // resolution for the attribute macro error.
+        const ATTRS_TO_CHECK: &[Symbol] =
+            &[sym::derive, sym::test, sym::test_case, sym::global_allocator, sym::bench];
+
+        // FIXME(jdonszelmann): all attrs should be combined here cleaning this up some day.
+        if let Some(name) = ATTRS_TO_CHECK.iter().find(|attr_to_check| matches!(attr.path.segments.as_ref(), [segment] if segment == *attr_to_check)) {
+            let span = attr.span;
+            let name = *name;
+
+            let item = self.first_line_of_next_item(span).map(|span| ItemFollowingInnerAttr { span });
+
+            let err = self.dcx().create_err(InvalidAttrAtCrateLevel {
+                span,
+                pound_to_opening_bracket: span.until(inner_span),
+                name,
+                item,
+            });
+
+            self.dcx().try_steal_replace_and_emit_err(
+                attr.path.span,
+                StashKey::UndeterminedMacroResolution,
+                err,
+            );
+        }
+    }
+
+    fn first_line_of_next_item(&self, span: Span) -> Option<Span> {
+        // We can't exactly call `tcx.hir_free_items()` here because it's too early and querying
+        // this would create a circular dependency. Instead, we resort to getting the original
+        // source code that follows `span` and find the next item from here.
+
+        self.sess()
+            .source_map()
+            .span_to_source(span, |content, _, span_end| {
+                let mut source = &content[span_end..];
+                let initial_source_len = source.len();
+                let span = try {
+                    loop {
+                        let first = source.chars().next()?;
+
+                        if first.is_whitespace() {
+                            let split_idx = source.find(|c: char| !c.is_whitespace())?;
+                            source = &source[split_idx..];
+                        } else if source.starts_with("//") {
+                            let line_idx = source.find('\n')?;
+                            source = &source[line_idx + '\n'.len_utf8()..];
+                        } else if source.starts_with("/*") {
+                            // FIXME: support nested comments.
+                            let close_idx = source.find("*/")?;
+                            source = &source[close_idx + "*/".len()..];
+                        } else if first == '#' {
+                            // FIXME: properly find the end of the attributes in order to accurately
+                            // skip them. This version just consumes the source code until the next
+                            // `]`.
+                            let close_idx = source.find(']')?;
+                            source = &source[close_idx + ']'.len_utf8()..];
+                        } else {
+                            let lo = span_end + initial_source_len - source.len();
+                            let last_line = source.split('\n').next().map(|s| s.trim_end())?;
+
+                            let hi = lo + last_line.len();
+                            let lo = BytePos(lo as u32);
+                            let hi = BytePos(hi as u32);
+                            let next_item_span = Span::new(lo, hi, span.ctxt(), None);
+
+                            break next_item_span;
+                        }
+                    }
+                };
+
+                Ok(span)
+            })
+            .ok()
+            .flatten()
+    }
+
+    pub(crate) fn check_invalid_where_predicate_attrs<'attr>(
+        &self,
+        attrs: impl IntoIterator<Item = &'attr Attribute>,
+    ) {
+        // FIXME(where_clause_attrs): Currently, as the following check shows,
+        // only `#[cfg]` and `#[cfg_attr]` are allowed, but it should be removed
+        // if we allow more attributes (e.g., tool attributes and `allow/deny/warn`)
+        // in where clauses. After that, this function would become useless.
+        let spans = attrs
+            .into_iter()
+            // FIXME: We shouldn't need to special-case `doc`!
+            .filter(|attr| {
+                matches!(
+                    attr,
+                    Attribute::Parsed(AttributeKind::DocComment { .. } | AttributeKind::Doc(_))
+                        | Attribute::Unparsed(_)
+                )
+            })
+            .map(|attr| attr.span())
+            .collect::<Vec<_>>();
+        if !spans.is_empty() {
+            self.dcx()
+                .emit_err(UnsupportedAttributesInWhere { span: MultiSpan::from_spans(spans) });
+        }
+    }
 }
 
 /// Takes a list of `allowed_targets` for an attribute, and the `target` the attribute was applied to.