Auto merge of rust-lang#116855 - matthiaskrgr:rollup-i2izdwb, r=matthiaskrgr

Rollup of 5 pull requests

Successful merges:

 - rust-lang#111072 (Add new simpler and more explicit syntax for check-cfg)
 - rust-lang#116717 (Special case iterator chain checks for suggestion)
 - rust-lang#116719 (Add MonoItems and Instance to stable_mir)
 - rust-lang#116787 (Implement an internal lint encouraging use of `Span::eq_ctxt`)
 - rust-lang#116827 (Make `handle_options` public again.)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_driver_impl/src/lib.rs

@@ -1185,7 +1185,11 @@ fn print_flag_list<T>(
 ///
 /// So with all that in mind, the comments below have some more detail about the
 /// contortions done here to get things to work out correctly.
-fn handle_options(handler: &EarlyErrorHandler, args: &[String]) -> Option<getopts::Matches> {
+///
+/// This does not need to be `pub` for rustc itself, but @chaosite needs it to
+/// be public when using rustc as a library, see
+/// <https://github.com/rust-lang/rust/commit/2b4c33817a5aaecabf4c6598d41e190080ec119e>
+pub fn handle_options(handler: &EarlyErrorHandler, args: &[String]) -> Option<getopts::Matches> {
     if args.is_empty() {
         // user did not write `-v` nor `-Z unstable-options`, so do not
         // include that extra information.

compiler/rustc_hir_typeck/src/callee.rs

@@ -650,7 +650,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 .sess
                 .source_map()
                 .is_multiline(call_expr.span.with_lo(callee_expr.span.hi()))
-                && call_expr.span.ctxt() == callee_expr.span.ctxt();
+                && call_expr.span.eq_ctxt(callee_expr.span);
             if call_is_multiline {
                 err.span_suggestion(
                     callee_expr.span.shrink_to_hi(),

compiler/rustc_interface/src/interface.rs

@@ -125,8 +125,13 @@ pub fn parse_cfgspecs(
 /// Converts strings provided as `--check-cfg [specs]` into a `CheckCfg`.
 pub fn parse_check_cfg(handler: &EarlyErrorHandler, specs: Vec<String>) -> CheckCfg {
     rustc_span::create_default_session_if_not_set_then(move |_| {
-        let mut check_cfg = CheckCfg::default();
+        // If any --check-cfg is passed then exhaustive_values and exhaustive_names
+        // are enabled by default.
+        let exhaustive_names = !specs.is_empty();
+        let exhaustive_values = !specs.is_empty();
+        let mut check_cfg = CheckCfg { exhaustive_names, exhaustive_values, ..CheckCfg::default() };
 
+        let mut old_syntax = None;
         for s in specs {
             let sess = ParseSess::with_silent_emitter(Some(format!(
                 "this error occurred on the command line: `--check-cfg={s}`"
@@ -142,18 +147,21 @@ pub fn parse_check_cfg(handler: &EarlyErrorHandler, specs: Vec<String>) -> Check
                 };
             }
 
-            let expected_error = || {
-                error!(
-                    "expected `names(name1, name2, ... nameN)` or \
-                        `values(name, \"value1\", \"value2\", ... \"valueN\")`"
-                )
-            };
+            let expected_error =
+                || error!("expected `cfg(name, values(\"value1\", \"value2\", ... \"valueN\"))`");
 
             match maybe_new_parser_from_source_str(&sess, filename, s.to_string()) {
                 Ok(mut parser) => match parser.parse_meta_item() {
                     Ok(meta_item) if parser.token == token::Eof => {
                         if let Some(args) = meta_item.meta_item_list() {
                             if meta_item.has_name(sym::names) {
+                                // defaults are flipped for the old syntax
+                                if old_syntax == None {
+                                    check_cfg.exhaustive_names = false;
+                                    check_cfg.exhaustive_values = false;
+                                }
+                                old_syntax = Some(true);
+
                                 check_cfg.exhaustive_names = true;
                                 for arg in args {
                                     if arg.is_word() && arg.ident().is_some() {
@@ -167,6 +175,13 @@ pub fn parse_check_cfg(handler: &EarlyErrorHandler, specs: Vec<String>) -> Check
                                     }
                                 }
                             } else if meta_item.has_name(sym::values) {
+                                // defaults are flipped for the old syntax
+                                if old_syntax == None {
+                                    check_cfg.exhaustive_names = false;
+                                    check_cfg.exhaustive_values = false;
+                                }
+                                old_syntax = Some(true);
+
                                 if let Some((name, values)) = args.split_first() {
                                     if name.is_word() && name.ident().is_some() {
                                         let ident = name.ident().expect("multi-segment cfg key");
@@ -216,6 +231,116 @@ pub fn parse_check_cfg(handler: &EarlyErrorHandler, specs: Vec<String>) -> Check
                                 } else {
                                     expected_error();
                                 }
+                            } else if meta_item.has_name(sym::cfg) {
+                                old_syntax = Some(false);
+
+                                let mut names = Vec::new();
+                                let mut values: FxHashSet<_> = Default::default();
+
+                                let mut any_specified = false;
+                                let mut values_specified = false;
+                                let mut values_any_specified = false;
+
+                                for arg in args {
+                                    if arg.is_word() && let Some(ident) = arg.ident() {
+                                        if values_specified {
+                                            error!("`cfg()` names cannot be after values");
+                                        }
+                                        names.push(ident);
+                                    } else if arg.has_name(sym::any)
+                                        && let Some(args) = arg.meta_item_list()
+                                    {
+                                        if any_specified {
+                                            error!("`any()` cannot be specified multiple times");
+                                        }
+                                        any_specified = true;
+                                        if !args.is_empty() {
+                                            error!("`any()` must be empty");
+                                        }
+                                    } else if arg.has_name(sym::values)
+                                        && let Some(args) = arg.meta_item_list()
+                                    {
+                                        if names.is_empty() {
+                                            error!(
+                                                "`values()` cannot be specified before the names"
+                                            );
+                                        } else if values_specified {
+                                            error!(
+                                                "`values()` cannot be specified multiple times"
+                                            );
+                                        }
+                                        values_specified = true;
+
+                                        for arg in args {
+                                            if let Some(LitKind::Str(s, _)) =
+                                                arg.lit().map(|lit| &lit.kind)
+                                            {
+                                                values.insert(Some(s.to_string()));
+                                            } else if arg.has_name(sym::any)
+                                                && let Some(args) = arg.meta_item_list()
+                                            {
+                                                if values_any_specified {
+                                                    error!(
+                                                        "`any()` in `values()` cannot be specified multiple times"
+                                                    );
+                                                }
+                                                values_any_specified = true;
+                                                if !args.is_empty() {
+                                                    error!("`any()` must be empty");
+                                                }
+                                            } else {
+                                                error!(
+                                                    "`values()` arguments must be string literals or `any()`"
+                                                );
+                                            }
+                                        }
+                                    } else {
+                                        error!(
+                                            "`cfg()` arguments must be simple identifiers, `any()` or `values(...)`"
+                                        );
+                                    }
+                                }
+
+                                if values.is_empty() && !values_any_specified && !any_specified {
+                                    values.insert(None);
+                                } else if !values.is_empty() && values_any_specified {
+                                    error!(
+                                        "`values()` arguments cannot specify string literals and `any()` at the same time"
+                                    );
+                                }
+
+                                if any_specified {
+                                    if !names.is_empty()
+                                        || !values.is_empty()
+                                        || values_any_specified
+                                    {
+                                        error!("`cfg(any())` can only be provided in isolation");
+                                    }
+
+                                    check_cfg.exhaustive_names = false;
+                                } else {
+                                    for name in names {
+                                        check_cfg
+                                            .expecteds
+                                            .entry(name.to_string())
+                                            .and_modify(|v| match v {
+                                                ExpectedValues::Some(v)
+                                                    if !values_any_specified =>
+                                                {
+                                                    v.extend(values.clone())
+                                                }
+                                                ExpectedValues::Some(_) => *v = ExpectedValues::Any,
+                                                ExpectedValues::Any => {}
+                                            })
+                                            .or_insert_with(|| {
+                                                if values_any_specified {
+                                                    ExpectedValues::Any
+                                                } else {
+                                                    ExpectedValues::Some(values.clone())
+                                                }
+                                            });
+                                    }
+                                }
                             } else {
                                 expected_error();
                             }

compiler/rustc_interface/src/lib.rs

@@ -3,6 +3,7 @@
 #![feature(internal_output_capture)]
 #![feature(thread_spawn_unchecked)]
 #![feature(lazy_cell)]
+#![feature(let_chains)]
 #![feature(try_blocks)]
 #![recursion_limit = "256"]
 #![allow(rustc::potential_query_instability)]

compiler/rustc_lint/messages.ftl

@@ -494,6 +494,8 @@ lint_renamed_lint = lint `{$name}` has been renamed to `{$replace}`
 
 lint_requested_level = requested on the command line with `{$level} {$lint_name}`
 
+lint_span_use_eq_ctxt = use `.eq_ctxt()` instead of `.ctxt() == .ctxt()`
+
 lint_supertrait_as_deref_target = `{$t}` implements `Deref` with supertrait `{$target_principal}` as target
     .label = target type is set here
 

compiler/rustc_lint/src/internal.rs

@@ -3,14 +3,14 @@
 
 use crate::lints::{
     BadOptAccessDiag, DefaultHashTypesDiag, DiagOutOfImpl, LintPassByHand, NonExistentDocKeyword,
-    QueryInstability, TyQualified, TykindDiag, TykindKind, UntranslatableDiag,
+    QueryInstability, SpanUseEqCtxtDiag, TyQualified, TykindDiag, TykindKind, UntranslatableDiag,
     UntranslatableDiagnosticTrivial,
 };
 use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
 use rustc_ast as ast;
 use rustc_hir::def::Res;
 use rustc_hir::{def_id::DefId, Expr, ExprKind, GenericArg, PatKind, Path, PathSegment, QPath};
-use rustc_hir::{HirId, Impl, Item, ItemKind, Node, Pat, Ty, TyKind};
+use rustc_hir::{BinOp, BinOpKind, HirId, Impl, Item, ItemKind, Node, Pat, Ty, TyKind};
 use rustc_middle::ty;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::hygiene::{ExpnKind, MacroKind};
@@ -537,3 +537,33 @@ impl LateLintPass<'_> for BadOptAccess {
         }
     }
 }
+
+declare_tool_lint! {
+    pub rustc::SPAN_USE_EQ_CTXT,
+    Allow,
+    "forbid uses of `==` with `Span::ctxt`, suggest `Span::eq_ctxt` instead",
+    report_in_external_macro: true
+}
+
+declare_lint_pass!(SpanUseEqCtxt => [SPAN_USE_EQ_CTXT]);
+
+impl<'tcx> LateLintPass<'tcx> for SpanUseEqCtxt {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &Expr<'_>) {
+        if let ExprKind::Binary(BinOp { node: BinOpKind::Eq, .. }, lhs, rhs) = expr.kind {
+            if is_span_ctxt_call(cx, lhs) && is_span_ctxt_call(cx, rhs) {
+                cx.emit_spanned_lint(SPAN_USE_EQ_CTXT, expr.span, SpanUseEqCtxtDiag);
+            }
+        }
+    }
+}
+
+fn is_span_ctxt_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
+    match &expr.kind {
+        ExprKind::MethodCall(..) => cx
+            .typeck_results()
+            .type_dependent_def_id(expr.hir_id)
+            .is_some_and(|call_did| cx.tcx.is_diagnostic_item(sym::SpanCtxt, call_did)),
+
+        _ => false,
+    }
+}

compiler/rustc_lint/src/lib.rs

@@ -531,6 +531,8 @@ fn register_internals(store: &mut LintStore) {
     store.register_late_mod_pass(|_| Box::new(BadOptAccess));
     store.register_lints(&PassByValue::get_lints());
     store.register_late_mod_pass(|_| Box::new(PassByValue));
+    store.register_lints(&SpanUseEqCtxt::get_lints());
+    store.register_late_mod_pass(|_| Box::new(SpanUseEqCtxt));
     // FIXME(davidtwco): deliberately do not include `UNTRANSLATABLE_DIAGNOSTIC` and
     // `DIAGNOSTIC_OUTSIDE_OF_IMPL` here because `-Wrustc::internal` is provided to every crate and
     // these lints will trigger all of the time - change this once migration to diagnostic structs
@@ -548,6 +550,7 @@ fn register_internals(store: &mut LintStore) {
             LintId::of(USAGE_OF_QUALIFIED_TY),
             LintId::of(EXISTING_DOC_KEYWORD),
             LintId::of(BAD_OPT_ACCESS),
+            LintId::of(SPAN_USE_EQ_CTXT),
         ],
     );
 }

compiler/rustc_lint/src/lints.rs

@@ -900,6 +900,10 @@ pub struct QueryInstability {
     pub query: Symbol,
 }
 
+#[derive(LintDiagnostic)]
+#[diag(lint_span_use_eq_ctxt)]
+pub struct SpanUseEqCtxtDiag;
+
 #[derive(LintDiagnostic)]
 #[diag(lint_tykind_kind)]
 pub struct TykindKind {

compiler/rustc_mir_transform/src/coverage/spans.rs

@@ -404,7 +404,7 @@ impl<'a> CoverageSpansGenerator<'a> {
 
         let Some(visible_macro) = curr.visible_macro(self.body_span) else { return };
         if let Some(prev) = &self.some_prev
-            && prev.expn_span.ctxt() == curr.expn_span.ctxt()
+            && prev.expn_span.eq_ctxt(curr.expn_span)
         {
             return;
         }

compiler/rustc_passes/src/loops.rs

@@ -231,7 +231,7 @@ impl<'a, 'hir> CheckLoopVisitor<'a, 'hir> {
             AsyncClosure(closure_span) => {
                 self.sess.emit_err(BreakInsideAsyncBlock { span, closure_span, name });
             }
-            UnlabeledBlock(block_span) if is_break && block_span.ctxt() == break_span.ctxt() => {
+            UnlabeledBlock(block_span) if is_break && block_span.eq_ctxt(break_span) => {
                 let suggestion = Some(OutsideLoopSuggestion { block_span, break_span });
                 self.sess.emit_err(OutsideLoop { span, name, is_break, suggestion });
             }