Fix Clippy handling of ExpnKind::Desugaring

src/bootstrap/test.rs

@@ -554,10 +554,7 @@ impl Step for Clippy {
 
         builder.add_rustc_lib_path(compiler, &mut cargo);
 
-        // FIXME: Disable clippy tests for now, they're failing on master
-        // (generally this would mean a toolstate failure but we don't have
-        // toolstate for clippy anymore).
-        // builder.run(&mut cargo.into());
+        builder.run(&mut cargo.into());
     }
 }
 

src/librustc_middle/lint.rs

@@ -7,8 +7,8 @@ use rustc_errors::{DiagnosticBuilder, DiagnosticId};
 use rustc_hir::HirId;
 use rustc_session::lint::{builtin, Level, Lint, LintId};
 use rustc_session::{DiagnosticMessageId, Session};
-use rustc_span::hygiene::MacroKind;
-use rustc_span::source_map::{DesugaringKind, ExpnKind, MultiSpan};
+use rustc_span::hygiene::{ClosestAstOrMacro, MacroKind};
+use rustc_span::source_map::{ExpnKind, MultiSpan};
 use rustc_span::{Span, Symbol};
 
 /// How a lint level was set.
@@ -337,16 +337,19 @@ pub fn struct_lint_level<'s, 'd>(
 /// This is used to test whether a lint should not even begin to figure out whether it should
 /// be reported on the current node.
 pub fn in_external_macro(sess: &Session, span: Span) -> bool {
-    let expn_data = span.ctxt().outer_expn_data();
-    match expn_data.kind {
-        ExpnKind::Root
-        | ExpnKind::Desugaring(DesugaringKind::ForLoop(_))
-        | ExpnKind::Desugaring(DesugaringKind::Operator) => false,
-        ExpnKind::AstPass(_) | ExpnKind::Desugaring(_) => true, // well, it's "external"
-        ExpnKind::Macro(MacroKind::Bang, _) => {
-            // Dummy span for the `def_site` means it's an external macro.
-            expn_data.def_site.is_dummy() || sess.source_map().is_imported(expn_data.def_site)
+    match span.ctxt().outer_expn().closest_ast_or_macro() {
+        ClosestAstOrMacro::Expn(expn_id) => {
+            let data = expn_id.expn_data();
+            match data.kind {
+                ExpnKind::Macro(MacroKind::Bang, _) => {
+                    // Dummy span for the `def_site` means it's an external macro.
+                    data.def_site.is_dummy() || sess.source_map().is_imported(data.def_site)
+                }
+                ExpnKind::Macro(_, _) => true, // definitely a plugin
+                ExpnKind::AstPass(_) => true,  // well, it's "External"
+                _ => unreachable!("unexpected ExpnData {:?}", data),
+            }
         }
-        ExpnKind::Macro(..) => true, // definitely a plugin
+        ClosestAstOrMacro::None => false,
     }
 }

src/librustc_span/hygiene.rs

@@ -104,9 +104,19 @@ impl ExpnId {
         HygieneData::with(|data| data.expn_data(self).clone())
     }
 
+    #[inline]
+    pub fn closest_ast_or_macro(self) -> ClosestAstOrMacro {
+        HygieneData::with(|data| data.closest_ast_or_macro(self))
+    }
+
     #[inline]
     pub fn set_expn_data(self, expn_data: ExpnData) {
         HygieneData::with(|data| {
+            let closest = data.determine_closest_ast_or_macro(self, &expn_data);
+            let old_closest = &mut data.closest_ast_or_macro[self.0 as usize];
+            assert!(old_closest.is_none(), "closest ast/macro data reset for an expansion ID");
+            *old_closest = Some(closest);
+
             let old_expn_data = &mut data.expn_data[self.0 as usize];
             assert!(old_expn_data.is_none(), "expansion data is reset for an expansion ID");
             *old_expn_data = Some(expn_data);
@@ -149,6 +159,10 @@ crate struct HygieneData {
     /// between creation of an expansion ID and obtaining its data (e.g. macros are collected
     /// first and then resolved later), so we use an `Option` here.
     expn_data: Vec<Option<ExpnData>>,
+    /// Stores the computed `ClosestAstOrMacro` for each `ExpnId`. This is updated
+    /// at the same time as `expn_data`, and its contents it determined entirely
+    /// by the `ExpnData` - this field is just a cache.
+    closest_ast_or_macro: Vec<Option<ClosestAstOrMacro>>,
     syntax_context_data: Vec<SyntaxContextData>,
     syntax_context_map: FxHashMap<(SyntaxContext, ExpnId, Transparency), SyntaxContext>,
 }
@@ -162,6 +176,7 @@ impl HygieneData {
                 edition,
                 Some(DefId::local(CRATE_DEF_INDEX)),
             ))],
+            closest_ast_or_macro: vec![Some(ClosestAstOrMacro::None)],
             syntax_context_data: vec![SyntaxContextData {
                 outer_expn: ExpnId::root(),
                 outer_transparency: Transparency::Opaque,
@@ -178,9 +193,36 @@ impl HygieneData {
         GLOBALS.with(|globals| f(&mut *globals.hygiene_data.borrow_mut()))
     }
 
+    fn determine_closest_ast_or_macro(
+        &self,
+        id: ExpnId,
+        expn_data: &ExpnData,
+    ) -> ClosestAstOrMacro {
+        match expn_data.kind {
+            ExpnKind::Macro(_, _) | ExpnKind::AstPass(_) => ClosestAstOrMacro::Expn(id),
+            ExpnKind::Desugaring(_) | ExpnKind::Root => {
+                // Avoid using `HygieneData` when construction root
+                // `ExpnData`
+                if expn_data.call_site.ctxt() == SyntaxContext::root() {
+                    ClosestAstOrMacro::None
+                } else {
+                    self.closest_ast_or_macro(self.outer_expn(expn_data.call_site.ctxt()))
+                }
+            }
+        }
+    }
+
+    fn closest_ast_or_macro(&self, expn_id: ExpnId) -> ClosestAstOrMacro {
+        self.closest_ast_or_macro[expn_id.0 as usize].as_ref().copied().unwrap()
+    }
+
     fn fresh_expn(&mut self, expn_data: Option<ExpnData>) -> ExpnId {
+        let expn_id = ExpnId(self.expn_data.len() as u32);
+        self.closest_ast_or_macro.push(
+            expn_data.as_ref().map(|data| self.determine_closest_ast_or_macro(expn_id, data)),
+        );
         self.expn_data.push(expn_data);
-        ExpnId(self.expn_data.len() as u32 - 1)
+        expn_id
     }
 
     fn expn_data(&self, expn_id: ExpnId) -> &ExpnData {
@@ -684,6 +726,22 @@ pub struct ExpnData {
     pub macro_def_id: Option<DefId>,
 }
 
+/// The closest `ExpnKind::AstPass` or `ExpnKind::Macro` to an `ExpnData`.
+/// 'Closest' is determined by starting at the current `ExpnData`,
+/// and walking up the `call_site` tree. If an `ExpnData` with
+/// `Expn::AstPass` or `ExpnKind::Macro` is found, it is represented
+/// by `ClosestAstOrMacro::Expn(id)`, where `id` is the `EpxId` of
+/// the found `ExpnData`.
+///
+/// A `ClosestAstOrMacro` implies that no `ExpnKind::AstPass` or `ExpnKind::Macro`
+/// are found anywhere in the `call_site` tree - that is, there no macro
+/// expansions or ast pass expansions.
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum ClosestAstOrMacro {
+    None,
+    Expn(ExpnId),
+}
+
 impl ExpnData {
     /// Constructs expansion data with default properties.
     pub fn default(

src/tools/clippy/clippy_lints/src/assertions_on_constants.rs

@@ -1,5 +1,5 @@
 use crate::consts::{constant, Constant};
-use crate::utils::paths;
+use crate::utils::{paths, in_macro};
 use crate::utils::{is_direct_expn_of, is_expn_of, match_function_call, snippet_opt, span_lint_and_help};
 use if_chain::if_chain;
 use rustc_ast::ast::LitKind;
@@ -67,7 +67,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssertionsOnConstants {
         };
 
         if let Some(debug_assert_span) = is_expn_of(e.span, "debug_assert") {
-            if debug_assert_span.from_expansion() {
+            if in_macro(debug_assert_span) {
                 return;
             }
             if_chain! {
@@ -79,7 +79,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssertionsOnConstants {
                 }
             };
         } else if let Some(assert_span) = is_direct_expn_of(e.span, "assert") {
-            if assert_span.from_expansion() {
+            if in_macro(assert_span) {
                 return;
             }
             if let Some(assert_match) = match_assert_with_message(&cx, e) {

src/tools/clippy/clippy_lints/src/attrs.rs

@@ -1,10 +1,7 @@
 //! checks for attributes
 
 use crate::reexport::Name;
-use crate::utils::{
-    first_line_of_span, is_present_in_source, match_def_path, paths, snippet_opt, span_lint, span_lint_and_sugg,
-    span_lint_and_then, without_block_comments,
-};
+use crate::utils::{first_line_of_span, is_present_in_source, match_def_path, paths, snippet_opt, span_lint, span_lint_and_sugg, span_lint_and_then, without_block_comments, in_macro};
 use if_chain::if_chain;
 use rustc_ast::ast::{AttrKind, AttrStyle, Attribute, Lit, LitKind, MetaItemKind, NestedMetaItem};
 use rustc_ast::util::lev_distance::find_best_match_for_name;
@@ -474,7 +471,7 @@ fn is_relevant_expr(cx: &LateContext<'_, '_>, tables: &ty::TypeckTables<'_>, exp
 }
 
 fn check_attrs(cx: &LateContext<'_, '_>, span: Span, name: Name, attrs: &[Attribute]) {
-    if span.from_expansion() {
+    if in_macro(span) {
         return;
     }
 

src/tools/clippy/clippy_lints/src/blocks_in_if_conditions.rs

@@ -1,4 +1,4 @@
-use crate::utils::{differing_macro_contexts, higher, snippet_block_with_applicability, span_lint, span_lint_and_sugg};
+use crate::utils::{differing_macro_contexts, higher, snippet_block_with_applicability, span_lint, span_lint_and_sugg, in_macro};
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
 use rustc_hir::{BlockCheckMode, Expr, ExprKind};
@@ -55,7 +55,7 @@ impl<'a, 'tcx> Visitor<'tcx> for ExVisitor<'a, 'tcx> {
         if let ExprKind::Closure(_, _, eid, _, _) = expr.kind {
             let body = self.cx.tcx.hir().body(eid);
             let ex = &body.value;
-            if matches!(ex.kind, ExprKind::Block(_, _)) && !body.value.span.from_expansion() {
+            if matches!(ex.kind, ExprKind::Block(_, _)) && !in_macro(body.value.span) {
                 self.found_block = Some(ex);
                 return;
             }
@@ -83,7 +83,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BlocksInIfConditions {
                         if let Some(ex) = &block.expr {
                             // don't dig into the expression here, just suggest that they remove
                             // the block
-                            if expr.span.from_expansion() || differing_macro_contexts(expr.span, ex.span) {
+                            if in_macro(expr.span) || differing_macro_contexts(expr.span, ex.span) {
                                 return;
                             }
                             let mut applicability = Applicability::MachineApplicable;
@@ -108,7 +108,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BlocksInIfConditions {
                         }
                     } else {
                         let span = block.expr.as_ref().map_or_else(|| block.stmts[0].span, |e| e.span);
-                        if span.from_expansion() || differing_macro_contexts(expr.span, span) {
+                        if in_macro(span) || differing_macro_contexts(expr.span, span) {
                             return;
                         }
                         // move block higher

src/tools/clippy/clippy_lints/src/booleans.rs

@@ -107,7 +107,7 @@ impl<'a, 'tcx, 'v> Hir2Qmm<'a, 'tcx, 'v> {
         }
 
         // prevent folding of `cfg!` macros and the like
-        if !e.span.from_expansion() {
+        if !in_macro(e.span) {
             match &e.kind {
                 ExprKind::Unary(UnOp::UnNot, inner) => return Ok(Bool::Not(box self.run(inner)?)),
                 ExprKind::Binary(binop, lhs, rhs) => match &binop.node {

src/tools/clippy/clippy_lints/src/cognitive_complexity.rs

@@ -9,7 +9,7 @@ use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::Span;
 use rustc_span::BytePos;
 
-use crate::utils::{is_type_diagnostic_item, snippet_opt, span_lint_and_help, LimitStack};
+use crate::utils::{is_type_diagnostic_item, snippet_opt, span_lint_and_help, LimitStack, in_macro};
 
 declare_clippy_lint! {
     /// **What it does:** Checks for methods with high cognitive complexity.
@@ -51,7 +51,7 @@ impl CognitiveComplexity {
         body: &'tcx Body<'_>,
         body_span: Span,
     ) {
-        if body_span.from_expansion() {
+        if in_macro(body_span) {
             return;
         }
 

src/tools/clippy/clippy_lints/src/collapsible_if.rs

@@ -18,7 +18,7 @@ use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
 use crate::utils::sugg::Sugg;
-use crate::utils::{snippet_block, snippet_block_with_applicability, span_lint_and_sugg, span_lint_and_then};
+use crate::utils::{snippet_block, snippet_block_with_applicability, span_lint_and_sugg, span_lint_and_then, in_macro};
 use rustc_errors::Applicability;
 
 declare_clippy_lint! {
@@ -75,7 +75,7 @@ declare_lint_pass!(CollapsibleIf => [COLLAPSIBLE_IF]);
 
 impl EarlyLintPass for CollapsibleIf {
     fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
-        if !expr.span.from_expansion() {
+        if !in_macro(expr.span) {
             check_if(cx, expr)
         }
     }
@@ -106,7 +106,7 @@ fn check_collapsible_maybe_if_let(cx: &EarlyContext<'_>, else_: &ast::Expr) {
         if let ast::ExprKind::Block(ref block, _) = else_.kind;
         if !block_starts_with_comment(cx, block);
         if let Some(else_) = expr_block(block);
-        if !else_.span.from_expansion();
+        if !in_macro(else_.span);
         if let ast::ExprKind::If(..) = else_.kind;
         then {
             let mut applicability = Applicability::MachineApplicable;

src/tools/clippy/clippy_lints/src/comparison_chain.rs

@@ -1,6 +1,4 @@
-use crate::utils::{
-    get_trait_def_id, if_sequence, implements_trait, parent_node_is_if_expr, paths, span_lint_and_help, SpanlessEq,
-};
+use crate::utils::{get_trait_def_id, if_sequence, implements_trait, parent_node_is_if_expr, paths, span_lint_and_help, SpanlessEq, in_macro};
 use rustc_hir::{BinOpKind, Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
@@ -54,7 +52,7 @@ declare_lint_pass!(ComparisonChain => [COMPARISON_CHAIN]);
 
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ComparisonChain {
     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
-        if expr.span.from_expansion() {
+        if in_macro(expr.span) {
             return;
         }
 

src/tools/clippy/clippy_lints/src/copies.rs

@@ -1,4 +1,4 @@
-use crate::utils::{get_parent_expr, higher, if_sequence, snippet, span_lint_and_note, span_lint_and_then};
+use crate::utils::{get_parent_expr, higher, if_sequence, snippet, span_lint_and_note, span_lint_and_then, in_macro};
 use crate::utils::{SpanlessEq, SpanlessHash};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::{Arm, Block, Expr, ExprKind, MatchSource, Pat, PatKind};
@@ -153,7 +153,7 @@ declare_lint_pass!(CopyAndPaste => [IFS_SAME_COND, SAME_FUNCTIONS_IN_IF_CONDITIO
 
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for CopyAndPaste {
     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
-        if !expr.span.from_expansion() {
+        if !in_macro(expr.span) {
             // skip ifs directly in else, it will be checked in the parent if
             if let Some(expr) = get_parent_expr(cx, expr) {
                 if let Some((_, _, Some(ref else_expr))) = higher::if_block(&expr) {

src/tools/clippy/clippy_lints/src/dereference.rs

@@ -1,4 +1,4 @@
-use crate::utils::{get_parent_expr, implements_trait, snippet, span_lint_and_sugg};
+use crate::utils::{get_parent_expr, implements_trait, snippet, span_lint_and_sugg, in_macro};
 use if_chain::if_chain;
 use rustc_ast::util::parser::{ExprPrecedence, PREC_POSTFIX, PREC_PREFIX};
 use rustc_errors::Applicability;
@@ -41,7 +41,7 @@ declare_lint_pass!(Dereferencing => [
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Dereferencing {
     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
         if_chain! {
-            if !expr.span.from_expansion();
+            if !in_macro(expr.span);
             if let ExprKind::MethodCall(ref method_name, _, ref args, _) = &expr.kind;
             if args.len() == 1;
 

src/tools/clippy/clippy_lints/src/double_parens.rs

@@ -1,4 +1,4 @@
-use crate::utils::span_lint;
+use crate::utils::{span_lint, in_macro};
 use rustc_ast::ast::{Expr, ExprKind};
 use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
@@ -41,7 +41,7 @@ declare_lint_pass!(DoubleParens => [DOUBLE_PARENS]);
 
 impl EarlyLintPass for DoubleParens {
     fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
-        if expr.span.from_expansion() {
+        if in_macro(expr.span) {
             return;
         }
 

src/tools/clippy/clippy_lints/src/enum_variants.rs

@@ -1,6 +1,6 @@
 //! lint on enum variants that are prefixed or suffixed by the same characters
 
-use crate::utils::{camel_case, is_present_in_source};
+use crate::utils::{camel_case, is_present_in_source, in_macro};
 use crate::utils::{span_lint, span_lint_and_help};
 use rustc_ast::ast::{EnumDef, Item, ItemKind, VisibilityKind};
 use rustc_lint::{EarlyContext, EarlyLintPass, Lint};
@@ -271,7 +271,7 @@ impl EarlyLintPass for EnumVariantNames {
         let item_name = item.ident.name.as_str();
         let item_name_chars = item_name.chars().count();
         let item_camel = to_camel_case(&item_name);
-        if !item.span.from_expansion() && is_present_in_source(cx, item.span) {
+        if !in_macro(item.span) && is_present_in_source(cx, item.span) {
             if let Some(&(ref mod_name, ref mod_camel)) = self.modules.last() {
                 // constants don't have surrounding modules
                 if !mod_camel.is_empty() {

src/tools/clippy/clippy_lints/src/eq_op.rs

@@ -56,7 +56,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EqOp {
     #[allow(clippy::similar_names, clippy::too_many_lines)]
     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr<'_>) {
         if let ExprKind::Binary(op, ref left, ref right) = e.kind {
-            if e.span.from_expansion() {
+            if in_macro(e.span) {
                 return;
             }
             let macro_with_not_op = |expr_kind: &ExprKind<'_>| {

src/tools/clippy/clippy_lints/src/erasing_op.rs

@@ -4,7 +4,7 @@ use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
 
 use crate::consts::{constant_simple, Constant};
-use crate::utils::span_lint;
+use crate::utils::{span_lint, in_macro};
 
 declare_clippy_lint! {
     /// **What it does:** Checks for erasing operations, e.g., `x * 0`.
@@ -31,7 +31,7 @@ declare_lint_pass!(ErasingOp => [ERASING_OP]);
 
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ErasingOp {
     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr<'_>) {
-        if e.span.from_expansion() {
+        if in_macro(e.span) {
             return;
         }
         if let ExprKind::Binary(ref cmp, ref left, ref right) = e.kind {