Auto merge of #100304 - matthiaskrgr:rollup-gs56vlw, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - #100163 (Refactor: remove an unnecessary string search)
 - #100212 (Remove more Clean trait implementations)
 - #100238 (Further improve error message for E0081)
 - #100268 (Add regression test for #79148)
 - #100294 (Update Duration::as_secs doc to point to as_secs_f64/32 for including fractional part)
 - #100303 (:arrow_up: rust-analyzer)

Failed merges:

 - #100281 (Remove more Clean trait implementations)

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

Author: bors

Diff for: compiler/rustc_typeck/src/check/check.rs

@@ -32,7 +32,6 @@ use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _;
 use rustc_trait_selection::traits::{self, ObligationCtxt};
 use rustc_ty_utils::representability::{self, Representability};
 
-use std::iter;
 use std::ops::ControlFlow;
 
 pub(super) fn check_abi(tcx: TyCtxt<'_>, hir_id: hir::HirId, span: Span, abi: Abi) {
@@ -1494,76 +1493,109 @@ fn check_enum<'tcx>(tcx: TyCtxt<'tcx>, vs: &'tcx [hir::Variant<'tcx>], def_id: L
         }
     }
 
-    let mut disr_vals: Vec<Discr<'tcx>> = Vec::with_capacity(vs.len());
-    // This tracks the previous variant span (in the loop) incase we need it for diagnostics
-    let mut prev_variant_span: Span = DUMMY_SP;
-    for ((_, discr), v) in iter::zip(def.discriminants(tcx), vs) {
-        // Check for duplicate discriminant values
-        if let Some(i) = disr_vals.iter().position(|&x| x.val == discr.val) {
-            let variant_did = def.variant(VariantIdx::new(i)).def_id;
-            let variant_i_hir_id = tcx.hir().local_def_id_to_hir_id(variant_did.expect_local());
-            let variant_i = tcx.hir().expect_variant(variant_i_hir_id);
-            let i_span = match variant_i.disr_expr {
-                Some(ref expr) => tcx.hir().span(expr.hir_id),
-                None => tcx.def_span(variant_did),
-            };
-            let span = match v.disr_expr {
-                Some(ref expr) => tcx.hir().span(expr.hir_id),
-                None => v.span,
-            };
-            let display_discr = format_discriminant_overflow(tcx, v, discr);
-            let display_discr_i = format_discriminant_overflow(tcx, variant_i, disr_vals[i]);
-            let no_disr = v.disr_expr.is_none();
-            let mut err = struct_span_err!(
-                tcx.sess,
-                sp,
-                E0081,
-                "discriminant value `{}` assigned more than once",
-                discr,
-            );
-
-            err.span_label(i_span, format!("first assignment of {display_discr_i}"));
-            err.span_label(span, format!("second assignment of {display_discr}"));
-
-            if no_disr {
-                err.span_label(
-                    prev_variant_span,
-                    format!(
-                        "assigned discriminant for `{}` was incremented from this discriminant",
-                        v.ident
-                    ),
-                );
-            }
-            err.emit();
-        }
-
-        disr_vals.push(discr);
-        prev_variant_span = v.span;
-    }
+    detect_discriminant_duplicate(tcx, def.discriminants(tcx).collect(), vs, sp);
 
     check_representable(tcx, sp, def_id);
     check_transparent(tcx, sp, def);
 }
 
-/// In the case that a discriminant is both a duplicate and an overflowing literal,
-/// we insert both the assigned discriminant and the literal it overflowed from into the formatted
-/// output. Otherwise we format the discriminant normally.
-fn format_discriminant_overflow<'tcx>(
+/// Part of enum check. Given the discriminants of an enum, errors if two or more discriminants are equal
+fn detect_discriminant_duplicate<'tcx>(
     tcx: TyCtxt<'tcx>,
-    variant: &hir::Variant<'_>,
-    dis: Discr<'tcx>,
-) -> String {
-    if let Some(expr) = &variant.disr_expr {
-        let body = &tcx.hir().body(expr.body).value;
-        if let hir::ExprKind::Lit(lit) = &body.kind
-            && let rustc_ast::LitKind::Int(lit_value, _int_kind) = &lit.node
-            && dis.val != *lit_value
-        {
-                    return format!("`{dis}` (overflowed from `{lit_value}`)");
+    mut discrs: Vec<(VariantIdx, Discr<'tcx>)>,
+    vs: &'tcx [hir::Variant<'tcx>],
+    self_span: Span,
+) {
+    // Helper closure to reduce duplicate code. This gets called everytime we detect a duplicate.
+    // Here `idx` refers to the order of which the discriminant appears, and its index in `vs`
+    let report = |dis: Discr<'tcx>,
+                  idx: usize,
+                  err: &mut DiagnosticBuilder<'_, ErrorGuaranteed>| {
+        let var = &vs[idx]; // HIR for the duplicate discriminant
+        let (span, display_discr) = match var.disr_expr {
+            Some(ref expr) => {
+                // In the case the discriminant is both a duplicate and overflowed, let the user know
+                if let hir::ExprKind::Lit(lit) = &tcx.hir().body(expr.body).value.kind
+                    && let rustc_ast::LitKind::Int(lit_value, _int_kind) = &lit.node
+                    && *lit_value != dis.val
+                {
+                    (tcx.hir().span(expr.hir_id), format!("`{dis}` (overflowed from `{lit_value}`)"))
+                // Otherwise, format the value as-is
+                } else {
+                    (tcx.hir().span(expr.hir_id), format!("`{dis}`"))
+                }
+            }
+            None => {
+                // At this point we know this discriminant is a duplicate, and was not explicitly
+                // assigned by the user. Here we iterate backwards to fetch the HIR for the last
+                // explictly assigned discriminant, and letting the user know that this was the
+                // increment startpoint, and how many steps from there leading to the duplicate
+                if let Some((n, hir::Variant { span, ident, .. })) =
+                    vs[..idx].iter().rev().enumerate().find(|v| v.1.disr_expr.is_some())
+                {
+                    let ve_ident = var.ident;
+                    let n = n + 1;
+                    let sp = if n > 1 { "variants" } else { "variant" };
+
+                    err.span_label(
+                        *span,
+                        format!("discriminant for `{ve_ident}` incremented from this startpoint (`{ident}` + {n} {sp} later => `{ve_ident}` = {dis})"),
+                    );
+                }
+
+                (vs[idx].span, format!("`{dis}`"))
+            }
+        };
+
+        err.span_label(span, format!("{display_discr} assigned here"));
+    };
+
+    // Here we loop through the discriminants, comparing each discriminant to another.
+    // When a duplicate is detected, we instatiate an error and point to both
+    // initial and duplicate value. The duplicate discriminant is then discarded by swapping
+    // it with the last element and decrementing the `vec.len` (which is why we have to evaluate
+    // `discrs.len()` anew every iteration, and why this could be tricky to do in a functional
+    // style as we are mutating `discrs` on the fly).
+    let mut i = 0;
+    while i < discrs.len() {
+        let hir_var_i_idx = discrs[i].0.index();
+        let mut error: Option<DiagnosticBuilder<'_, _>> = None;
+
+        let mut o = i + 1;
+        while o < discrs.len() {
+            let hir_var_o_idx = discrs[o].0.index();
+
+            if discrs[i].1.val == discrs[o].1.val {
+                let err = error.get_or_insert_with(|| {
+                    let mut ret = struct_span_err!(
+                        tcx.sess,
+                        self_span,
+                        E0081,
+                        "discriminant value `{}` assigned more than once",
+                        discrs[i].1,
+                    );
+
+                    report(discrs[i].1, hir_var_i_idx, &mut ret);
+
+                    ret
+                });
+
+                report(discrs[o].1, hir_var_o_idx, err);
+
+                // Safe to unwrap here, as we wouldn't reach this point if `discrs` was empty
+                discrs[o] = *discrs.last().unwrap();
+                discrs.pop();
+            } else {
+                o += 1;
+            }
         }
-    }
 
-    format!("`{dis}`")
+        if let Some(mut e) = error {
+            e.emit();
+        }
+
+        i += 1;
+    }
 }
 
 pub(super) fn check_type_params_are_used<'tcx>(

Diff for: compiler/rustc_typeck/src/check/expr.rs

@@ -50,7 +50,6 @@ use rustc_span::hygiene::DesugaringKind;
 use rustc_span::lev_distance::find_best_match_for_name;
 use rustc_span::source_map::{Span, Spanned};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
-use rustc_span::{BytePos, Pos};
 use rustc_target::spec::abi::Abi::RustIntrinsic;
 use rustc_trait_selection::infer::InferCtxtExt;
 use rustc_trait_selection::traits::{self, ObligationCauseCode};
@@ -2398,37 +2397,29 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 expr,
                 Some(span),
             );
+        } else if let ty::RawPtr(ty_and_mut) = expr_t.kind()
+            && let ty::Adt(adt_def, _) = ty_and_mut.ty.kind()
+            && let ExprKind::Field(base_expr, _) = expr.kind
+            && adt_def.variants().len() == 1
+            && adt_def
+                .variants()
+                .iter()
+                .next()
+                .unwrap()
+                .fields
+                .iter()
+                .any(|f| f.ident(self.tcx) == field)
+        {
+            err.multipart_suggestion(
+                "to access the field, dereference first",
+                vec![
+                    (base_expr.span.shrink_to_lo(), "(*".to_string()),
+                    (base_expr.span.shrink_to_hi(), ")".to_string()),
+                ],
+                Applicability::MaybeIncorrect,
+            );
         } else {
-            let mut found = false;
-
-            if let ty::RawPtr(ty_and_mut) = expr_t.kind()
-                && let ty::Adt(adt_def, _) = ty_and_mut.ty.kind()
-            {
-                if adt_def.variants().len() == 1
-                    && adt_def
-                        .variants()
-                        .iter()
-                        .next()
-                        .unwrap()
-                        .fields
-                        .iter()
-                        .any(|f| f.ident(self.tcx) == field)
-                {
-                    if let Some(dot_loc) = expr_snippet.rfind('.') {
-                        found = true;
-                        err.span_suggestion(
-                            expr.span.with_hi(expr.span.lo() + BytePos::from_usize(dot_loc)),
-                            "to access the field, dereference first",
-                            format!("(*{})", &expr_snippet[0..dot_loc]),
-                            Applicability::MaybeIncorrect,
-                        );
-                    }
-                }
-            }
-
-            if !found {
-                err.help("methods are immutable and cannot be assigned to");
-            }
+            err.help("methods are immutable and cannot be assigned to");
         }
 
         err.emit();

Diff for: compiler/rustc_typeck/src/check/mod.rs

@@ -112,7 +112,6 @@ use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::intravisit::Visitor;
 use rustc_hir::{HirIdMap, ImplicitSelfKind, Node};
 use rustc_index::bit_set::BitSet;
-use rustc_index::vec::Idx;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::subst::{InternalSubsts, Subst, SubstsRef};

Diff for: library/core/src/time.rs

@@ -318,19 +318,11 @@ impl Duration {
     /// assert_eq!(duration.as_secs(), 5);
     /// ```
     ///
-    /// To determine the total number of seconds represented by the `Duration`,
-    /// use `as_secs` in combination with [`subsec_nanos`]:
-    ///
-    /// ```
-    /// use std::time::Duration;
-    ///
-    /// let duration = Duration::new(5, 730023852);
-    ///
-    /// assert_eq!(5.730023852,
-    ///            duration.as_secs() as f64
-    ///            + duration.subsec_nanos() as f64 * 1e-9);
-    /// ```
+    /// To determine the total number of seconds represented by the `Duration`
+    /// including the fractional part, use [`as_secs_f64`] or [`as_secs_f32`]
     ///
+    /// [`as_secs_f32`]: Duration::as_secs_f64
+    /// [`as_secs_f64`]: Duration::as_secs_f32
     /// [`subsec_nanos`]: Duration::subsec_nanos
     #[stable(feature = "duration", since = "1.3.0")]
     #[rustc_const_stable(feature = "duration_consts", since = "1.32.0")]

Diff for: src/librustdoc/clean/auto_trait.rs

@@ -476,7 +476,7 @@ where
         let mut ty_to_fn: FxHashMap<Type, (PolyTrait, Option<Type>)> = Default::default();
 
         for p in clean_where_predicates {
-            let (orig_p, p) = (p, p.clean(self.cx));
+            let (orig_p, p) = (p, clean_predicate(p, self.cx));
             if p.is_none() {
                 continue;
             }