Convert two rustc_middle::lint functions to Span methods.

`rustc_middle` is a huge crate and it's always good to move stuff out of
it. There are lots of similar methods already on `Span`, so these two
functions, `in_external_macro` and `is_from_async_await`, fit right in.
The diff is big because `in_external_macro` is used a lot by clippy
lints.

Author: nnethercote

compiler/rustc_hir_typeck/src/coercion.rs

@@ -50,7 +50,6 @@ use rustc_infer::traits::{
     IfExpressionCause, MatchExpressionArmCause, Obligation, PredicateObligation,
     PredicateObligations,
 };
-use rustc_middle::lint::in_external_macro;
 use rustc_middle::span_bug;
 use rustc_middle::traits::BuiltinImplSource;
 use rustc_middle::ty::adjustment::{
@@ -1937,7 +1936,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
                     cond_expr.span.desugaring_kind(),
                     None | Some(DesugaringKind::WhileLoop)
                 )
-                && !in_external_macro(fcx.tcx.sess, cond_expr.span)
+                && !cond_expr.span.in_external_macro(fcx.tcx.sess.source_map())
                 && !matches!(
                     cond_expr.kind,
                     hir::ExprKind::Match(.., hir::MatchSource::TryDesugar(_))

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -14,7 +14,6 @@ use rustc_hir::{
 };
 use rustc_hir_analysis::hir_ty_lowering::HirTyLowerer;
 use rustc_hir_analysis::suggest_impl_trait;
-use rustc_middle::lint::in_external_macro;
 use rustc_middle::middle::stability::EvalResult;
 use rustc_middle::span_bug;
 use rustc_middle::ty::print::with_no_trimmed_paths;
@@ -770,7 +769,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         // If the expression is from an external macro, then do not suggest
                         // adding a semicolon, because there's nowhere to put it.
                         // See issue #81943.
-                        && !in_external_macro(self.tcx.sess, expression.span) =>
+                        && !expression.span.in_external_macro(self.tcx.sess.source_map()) =>
                 {
                     if needs_block {
                         err.multipart_suggestion(
@@ -2265,7 +2264,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expected: Ty<'tcx>,
         expr_ty: Ty<'tcx>,
     ) -> bool {
-        if in_external_macro(self.tcx.sess, expr.span) {
+        if expr.span.in_external_macro(self.tcx.sess.source_map()) {
             return false;
         }
         if let ty::Adt(expected_adt, args) = expected.kind() {
@@ -2593,14 +2592,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     )> {
         let sess = self.sess();
         let sp = expr.span;
+        let sm = sess.source_map();
 
         // If the span is from an external macro, there's no suggestion we can make.
-        if in_external_macro(sess, sp) {
+        if sp.in_external_macro(sm) {
             return None;
         }
 
-        let sm = sess.source_map();
-
         let replace_prefix = |s: &str, old: &str, new: &str| {
             s.strip_prefix(old).map(|stripped| new.to_string() + stripped)
         };

compiler/rustc_lint/src/builtin.rs

@@ -29,7 +29,6 @@ use rustc_hir::def_id::{CRATE_DEF_ID, DefId, LocalDefId};
 use rustc_hir::intravisit::FnKind as HirFnKind;
 use rustc_hir::{Body, FnDecl, GenericParamKind, PatKind, PredicateOrigin};
 use rustc_middle::bug;
-use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt, Upcast, VariantDef};
@@ -2029,7 +2028,7 @@ impl ExplicitOutlivesRequirements {
                 }
 
                 let span = bound.span().find_ancestor_inside(predicate_span)?;
-                if in_external_macro(tcx.sess, span) {
+                if span.in_external_macro(tcx.sess.source_map()) {
                     return None;
                 }
 

compiler/rustc_lint/src/early/diagnostics/check_cfg.rs

@@ -135,7 +135,7 @@ pub(super) fn unexpected_cfg_name(
     };
 
     let is_from_cargo = rustc_session::utils::was_invoked_from_cargo();
-    let is_from_external_macro = rustc_middle::lint::in_external_macro(sess, name_span);
+    let is_from_external_macro = name_span.in_external_macro(sess.source_map());
     let mut is_feature_cfg = name == sym::feature;
 
     let code_sugg = if is_feature_cfg && is_from_cargo {
@@ -281,7 +281,7 @@ pub(super) fn unexpected_cfg_value(
         .collect();
 
     let is_from_cargo = rustc_session::utils::was_invoked_from_cargo();
-    let is_from_external_macro = rustc_middle::lint::in_external_macro(sess, name_span);
+    let is_from_external_macro = name_span.in_external_macro(sess.source_map());
 
     // Show the full list if all possible values for a given name, but don't do it
     // for names as the possibilities could be very long

compiler/rustc_lint/src/non_fmt_panic.rs

@@ -2,7 +2,6 @@ use rustc_ast as ast;
 use rustc_errors::Applicability;
 use rustc_hir::{self as hir, LangItem};
 use rustc_infer::infer::TyCtxtInferExt;
-use rustc_middle::lint::in_external_macro;
 use rustc_middle::{bug, ty};
 use rustc_parse_format::{ParseMode, Parser, Piece};
 use rustc_session::lint::FutureIncompatibilityReason;
@@ -100,7 +99,7 @@ fn check_panic<'tcx>(cx: &LateContext<'tcx>, f: &'tcx hir::Expr<'tcx>, arg: &'tc
 
     let (span, panic, symbol) = panic_call(cx, f);
 
-    if in_external_macro(cx.sess(), span) {
+    if span.in_external_macro(cx.sess().source_map()) {
         // Nothing that can be done about it in the current crate.
         return;
     }
@@ -229,14 +228,15 @@ fn check_panic_str<'tcx>(
 
     let (span, _, _) = panic_call(cx, f);
 
-    if in_external_macro(cx.sess(), span) && in_external_macro(cx.sess(), arg.span) {
+    let sm = cx.sess().source_map();
+    if span.in_external_macro(sm) && arg.span.in_external_macro(sm) {
         // Nothing that can be done about it in the current crate.
         return;
     }
 
     let fmt_span = arg.span.source_callsite();
 
-    let (snippet, style) = match cx.sess().psess.source_map().span_to_snippet(fmt_span) {
+    let (snippet, style) = match sm.span_to_snippet(fmt_span) {
         Ok(snippet) => {
             // Count the number of `#`s between the `r` and `"`.
             let style = snippet.strip_prefix('r').and_then(|s| s.find('"'));
@@ -283,7 +283,7 @@ fn check_panic_str<'tcx>(
 /// Given the span of `some_macro!(args);`, gives the span of `(` and `)`,
 /// and the type of (opening) delimiter used.
 fn find_delimiters(cx: &LateContext<'_>, span: Span) -> Option<(Span, Span, char)> {
-    let snippet = cx.sess().psess.source_map().span_to_snippet(span).ok()?;
+    let snippet = cx.sess().source_map().span_to_snippet(span).ok()?;
     let (open, open_ch) = snippet.char_indices().find(|&(_, c)| "([{".contains(c))?;
     let close = snippet.rfind(|c| ")]}".contains(c))?;
     Some((

compiler/rustc_middle/src/lint.rs

@@ -8,8 +8,7 @@ use rustc_macros::{Decodable, Encodable, HashStable};
 use rustc_session::Session;
 use rustc_session::lint::builtin::{self, FORBIDDEN_LINT_GROUPS};
 use rustc_session::lint::{FutureIncompatibilityReason, Level, Lint, LintExpectationId, LintId};
-use rustc_span::hygiene::{ExpnKind, MacroKind};
-use rustc_span::{DUMMY_SP, DesugaringKind, Span, Symbol, kw};
+use rustc_span::{DUMMY_SP, Span, Symbol, kw};
 use tracing::instrument;
 
 use crate::ty::TyCtxt;
@@ -201,7 +200,7 @@ impl LintExpectation {
     }
 }
 
-pub fn explain_lint_level_source(
+fn explain_lint_level_source(
     lint: &'static Lint,
     level: Level,
     src: LintLevelSource,
@@ -325,7 +324,7 @@ pub fn lint_level(
         // If this code originates in a foreign macro, aka something that this crate
         // did not itself author, then it's likely that there's nothing this crate
         // can do about it. We probably want to skip the lint entirely.
-        if err.span.primary_spans().iter().any(|s| in_external_macro(sess, *s)) {
+        if err.span.primary_spans().iter().any(|s| s.in_external_macro(sess.source_map())) {
             // Any suggestions made here are likely to be incorrect, so anything we
             // emit shouldn't be automatically fixed by rustfix.
             err.disable_suggestions();
@@ -422,36 +421,3 @@ pub fn lint_level(
     }
     lint_level_impl(sess, lint, level, src, span, Box::new(decorate))
 }
-
-/// Returns whether `span` originates in a foreign crate's external macro.
-///
-/// 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
-            | DesugaringKind::WhileLoop
-            | DesugaringKind::OpaqueTy
-            | DesugaringKind::Async
-            | DesugaringKind::Await,
-        ) => 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)
-        }
-        ExpnKind::Macro { .. } => true, // definitely a plugin
-    }
-}
-
-/// Return whether `span` is generated by `async` or `await`.
-pub fn is_from_async_await(span: Span) -> bool {
-    let expn_data = span.ctxt().outer_expn_data();
-    match expn_data.kind {
-        ExpnKind::Desugaring(DesugaringKind::Async | DesugaringKind::Await) => true,
-        _ => false,
-    }
-}

compiler/rustc_span/src/lib.rs

@@ -600,11 +600,43 @@ impl Span {
         !self.is_dummy() && sm.is_span_accessible(self)
     }
 
+    /// Returns whether `span` originates in a foreign crate's external macro.
+    ///
+    /// 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(self, sm: &SourceMap) -> bool {
+        let expn_data = self.ctxt().outer_expn_data();
+        match expn_data.kind {
+            ExpnKind::Root
+            | ExpnKind::Desugaring(
+                DesugaringKind::ForLoop
+                | DesugaringKind::WhileLoop
+                | DesugaringKind::OpaqueTy
+                | DesugaringKind::Async
+                | DesugaringKind::Await,
+            ) => 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() || sm.is_imported(expn_data.def_site)
+            }
+            ExpnKind::Macro { .. } => true, // definitely a plugin
+        }
+    }
+
     /// Returns `true` if `span` originates in a derive-macro's expansion.
     pub fn in_derive_expansion(self) -> bool {
         matches!(self.ctxt().outer_expn_data().kind, ExpnKind::Macro(MacroKind::Derive, _))
     }
 
+    /// Return whether `span` is generated by `async` or `await`.
+    pub fn is_from_async_await(self) -> bool {
+        matches!(
+            self.ctxt().outer_expn_data().kind,
+            ExpnKind::Desugaring(DesugaringKind::Async | DesugaringKind::Await),
+        )
+    }
+
     /// Gate suggestions that would not be appropriate in a context the user didn't write.
     pub fn can_be_used_for_suggestions(self) -> bool {
         !self.from_expansion()

src/tools/clippy/book/src/development/adding_lints.md

@@ -788,7 +788,7 @@ don't hesitate to ask on [Zulip] or in the issue/PR.
 [`snippet`]: https://doc.rust-lang.org/nightly/nightly-rustc/clippy_utils/source/fn.snippet.html
 [let-chains]: https://github.com/rust-lang/rust/pull/94927
 [from_expansion]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/struct.Span.html#method.from_expansion
-[in_external_macro]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/lint/fn.in_external_macro.html
+[in_external_macro]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/struct.Span.html#method.in_external_macro
 [span]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/struct.Span.html
 [applicability]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_errors/enum.Applicability.html
 [rustc-dev-guide]: https://rustc-dev-guide.rust-lang.org/

src/tools/clippy/book/src/development/common_tools_writing_lints.md

@@ -218,7 +218,7 @@ functions to deal with macros:
   > context. And so just using `span.from_expansion()` is often good enough.
 
 
-- `in_external_macro(span)`: detect if the given span is from a macro defined in
+- `span.in_external_macro(sm)`: detect if the given span is from a macro defined in
   a foreign crate. If you want the lint to work with macro-generated code, this
   is the next line of defense to avoid macros not defined in the current crate.
   It doesn't make sense to lint code that the coder can't change.
@@ -227,15 +227,13 @@ functions to deal with macros:
   crates
 
   ```rust
-  use rustc_middle::lint::in_external_macro;
-
   use a_crate_with_macros::foo;
 
   // `foo` is defined in `a_crate_with_macros`
   foo!("bar");
 
   // if we lint the `match` of `foo` call and test its span
-  assert_eq!(in_external_macro(cx.sess(), match_span), true);
+  assert_eq!(match_span.in_external_macro(cx.sess().source_map()), true);
   ```
 
 - `span.ctxt()`: the span's context represents whether it is from expansion, and

src/tools/clippy/book/src/development/macro_expansions.md

@@ -120,7 +120,7 @@ assert_ne!(x_is_some_span.ctxt(), x_unwrap_span.ctxt());
 
 ### The `in_external_macro` function
 
-`rustc_middle::lint` provides a function ([`in_external_macro`]) that can
+`Span` provides a method ([`in_external_macro`]) that can
 detect if the given span is from a macro defined in a foreign crate.
 
 Therefore, if we really want a new lint to work with macro-generated code,
@@ -144,7 +144,7 @@ Also assume that we get the corresponding variable `foo_span` for the
 results in `true` (note that `cx` can be `EarlyContext` or `LateContext`):
 
 ```rust
-if in_external_macro(cx.sess(), foo_span) {
+if foo_span.in_external_macro(cx.sess().source_map()) {
     // We should ignore macro from a foreign crate.
     return;
 }
@@ -153,6 +153,6 @@ if in_external_macro(cx.sess(), foo_span) {
 [`ctxt`]: https://doc.rust-lang.org/stable/nightly-rustc/rustc_span/struct.Span.html#method.ctxt
 [expansion]: https://rustc-dev-guide.rust-lang.org/macro-expansion.html#expansion-and-ast-integration
 [`from_expansion`]: https://doc.rust-lang.org/stable/nightly-rustc/rustc_span/struct.Span.html#method.from_expansion
-[`in_external_macro`]: https://doc.rust-lang.org/stable/nightly-rustc/rustc_middle/lint/fn.in_external_macro.html
+[`in_external_macro`]: https://doc.rust-lang.org/stable/nightly-rustc/rustc_span/struct.Span.html#method.in_external_macro
 [Span]: https://doc.rust-lang.org/stable/nightly-rustc/rustc_span/struct.Span.html
 [SyntaxContext]: https://doc.rust-lang.org/stable/nightly-rustc/rustc_span/hygiene/struct.SyntaxContext.html