Auto merge of rust-lang#106914 - matthiaskrgr:rollup-yh0x4gq, r=matthiaskrgr

Rollup of 5 pull requests

Successful merges:

 - rust-lang#106888 (Add tidy check to ensure that rustdoc GUI tests start with a small description)
 - rust-lang#106896 (suggest `is_empty` for collections when casting to `bool`)
 - rust-lang#106900 (Fix regression in `unused_braces` with macros)
 - rust-lang#106906 (remove redundant clones)
 - rust-lang#106909 (Only suggest adding type param if path being resolved was a type)

Failed merges:

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

Author: bors

compiler/rustc_hir_typeck/src/cast.rs

@@ -31,7 +31,9 @@
 use super::FnCtxt;
 
 use crate::type_error_struct;
-use rustc_errors::{struct_span_err, Applicability, DelayDm, DiagnosticBuilder, ErrorGuaranteed};
+use rustc_errors::{
+    struct_span_err, Applicability, DelayDm, Diagnostic, DiagnosticBuilder, ErrorGuaranteed,
+};
 use rustc_hir as hir;
 use rustc_macros::{TypeFoldable, TypeVisitable};
 use rustc_middle::mir::Mutability;
@@ -270,6 +272,9 @@ impl<'a, 'tcx> CastCheck<'tcx> {
                         }
                     ));
                 }
+
+                self.try_suggest_collection_to_bool(fcx, &mut err);
+
                 err.emit();
             }
             CastError::NeedViaInt => {
@@ -517,6 +522,9 @@ impl<'a, 'tcx> CastCheck<'tcx> {
                 } else {
                     err.span_label(self.span, "invalid cast");
                 }
+
+                self.try_suggest_collection_to_bool(fcx, &mut err);
+
                 err.emit();
             }
             CastError::SizedUnsizedCast => {
@@ -1080,4 +1088,40 @@ impl<'a, 'tcx> CastCheck<'tcx> {
             },
         );
     }
+
+    /// Attempt to suggest using `.is_empty` when trying to cast from a
+    /// collection type to a boolean.
+    fn try_suggest_collection_to_bool(&self, fcx: &FnCtxt<'a, 'tcx>, err: &mut Diagnostic) {
+        if self.cast_ty.is_bool() {
+            let derefed = fcx
+                .autoderef(self.expr_span, self.expr_ty)
+                .silence_errors()
+                .find(|t| matches!(t.0.kind(), ty::Str | ty::Slice(..)));
+
+            if let Some((deref_ty, _)) = derefed {
+                // Give a note about what the expr derefs to.
+                if deref_ty != self.expr_ty.peel_refs() {
+                    err.span_note(
+                        self.expr_span,
+                        format!(
+                            "this expression `Deref`s to `{}` which implements `is_empty`",
+                            fcx.ty_to_string(deref_ty)
+                        ),
+                    );
+                }
+
+                // Create a multipart suggestion: add `!` and `.is_empty()` in
+                // place of the cast.
+                let suggestion = vec![
+                    (self.expr_span.shrink_to_lo(), "!".to_string()),
+                    (self.span.with_lo(self.expr_span.hi()), ".is_empty()".to_string()),
+                ];
+
+                err.multipart_suggestion_verbose(format!(
+                    "consider using the `is_empty` method on `{}` to determine if it contains anything",
+                    fcx.ty_to_string(self.expr_ty),
+                ),  suggestion, Applicability::MaybeIncorrect);
+            }
+        }
+    }
 }

compiler/rustc_lint/src/internal.rs

@@ -187,9 +187,9 @@ impl<'tcx> LateLintPass<'tcx> for TyTyKind {
                         },
                         None => cx.emit_spanned_lint(USAGE_OF_TY_TYKIND, path.span, TykindDiag),
                     }
-                } else if !ty.span.from_expansion() && path.segments.len() > 1 && let Some(t) = is_ty_or_ty_ctxt(cx, &path) {
+                } else if !ty.span.from_expansion() && path.segments.len() > 1 && let Some(ty) = is_ty_or_ty_ctxt(cx, &path) {
                     cx.emit_spanned_lint(USAGE_OF_QUALIFIED_TY, path.span, TyQualified {
-                        ty: t.clone(),
+                        ty,
                         suggestion: path.span,
                     });
                 }

compiler/rustc_lint/src/pass_by_value.rs

@@ -32,7 +32,7 @@ impl<'tcx> LateLintPass<'tcx> for PassByValue {
                     cx.emit_spanned_lint(
                         PASS_BY_VALUE,
                         ty.span,
-                        PassByValueDiag { ty: t.clone(), suggestion: ty.span },
+                        PassByValueDiag { ty: t, suggestion: ty.span },
                     );
                 }
             }

compiler/rustc_lint/src/unused.rs

@@ -1095,17 +1095,21 @@ impl UnusedDelimLint for UnusedBraces {
                 //      ```
                 // - the block has no attribute and was not created inside a macro
                 // - if the block is an `anon_const`, the inner expr must be a literal
-                //      (do not lint `struct A<const N: usize>; let _: A<{ 2 + 3 }>;`)
-                //
+                //   not created by a macro, i.e. do not lint on:
+                //      ```
+                //      struct A<const N: usize>;
+                //      let _: A<{ 2 + 3 }>;
+                //      let _: A<{produces_literal!()}>;
+                //      ```
                 // FIXME(const_generics): handle paths when #67075 is fixed.
                 if let [stmt] = inner.stmts.as_slice() {
                     if let ast::StmtKind::Expr(ref expr) = stmt.kind {
                         if !Self::is_expr_delims_necessary(expr, followed_by_block, false)
                             && (ctx != UnusedDelimsCtx::AnonConst
-                                || matches!(expr.kind, ast::ExprKind::Lit(_)))
+                                || (matches!(expr.kind, ast::ExprKind::Lit(_))
+                                    && !expr.span.from_expansion()))
                             && !cx.sess().source_map().is_multiline(value.span)
                             && value.attrs.is_empty()
-                            && !expr.span.from_expansion()
                             && !value.span.from_expansion()
                             && !inner.span.from_expansion()
                         {

compiler/rustc_resolve/src/late.rs

@@ -3373,7 +3373,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                         sugg.to_string(),
                         Applicability::MaybeIncorrect,
                     ))
-                } else if res.is_none() {
+                } else if res.is_none() && matches!(source, PathSource::Type) {
                     this.report_missing_type_error(path)
                 } else {
                     None

src/tools/tidy/src/lib.rs

@@ -62,6 +62,7 @@ pub mod features;
 pub mod mir_opt_tests;
 pub mod pal;
 pub mod primitive_docs;
+pub mod rustdoc_gui_tests;
 pub mod style;
 pub mod target_specific_tests;
 pub mod tests_placement;

src/tools/tidy/src/main.rs

@@ -80,6 +80,7 @@ fn main() {
         check!(debug_artifacts, &tests_path);
         check!(ui_tests, &tests_path);
         check!(mir_opt_tests, &tests_path, bless);
+        check!(rustdoc_gui_tests, &tests_path);
 
         // Checks that only make sense for the compiler.
         check!(error_codes, &root_path, &[&compiler_path, &librustdoc_path], verbose);

src/tools/tidy/src/rustdoc_gui_tests.rs

@@ -0,0 +1,33 @@
+//! Tidy check to ensure that rustdoc GUI tests start with a small description.
+
+use std::path::Path;
+
+pub fn check(path: &Path, bad: &mut bool) {
+    crate::walk::walk(
+        &path.join("rustdoc-gui"),
+        &mut |p| {
+            // If there is no extension, it's very likely a folder and we want to go into it.
+            p.extension().map(|e| e != "goml").unwrap_or(false)
+        },
+        &mut |entry, content| {
+            for line in content.lines() {
+                if !line.starts_with("// ") {
+                    tidy_error!(
+                        bad,
+                        "{}: rustdoc-gui tests must start with a small description",
+                        entry.path().display(),
+                    );
+                    return;
+                } else if line.starts_with("// ") {
+                    let parts = line[2..].trim();
+                    // We ignore tidy comments.
+                    if parts.starts_with("// tidy-") {
+                        continue;
+                    }
+                    // All good!
+                    return;
+                }
+            }
+        },
+    );
+}

tests/rustdoc-gui/basic-code.goml

@@ -1,3 +1,5 @@
+// Small test to ensure the "src-line-numbers" element is only present once on
+// the page.
 goto: "file://" + |DOC_PATH| + "/test_docs/index.html"
 click: ".srclink"
 wait-for: ".src-line-numbers"

tests/ui/cast/cast-as-bool.rs

@@ -2,8 +2,12 @@ fn main() {
     let u = 5 as bool; //~ ERROR cannot cast as `bool`
                        //~| HELP compare with zero instead
                        //~| SUGGESTION 5 != 0
+
     let t = (1 + 2) as bool; //~ ERROR cannot cast as `bool`
                              //~| HELP compare with zero instead
                              //~| SUGGESTION (1 + 2) != 0
-    let v = "hello" as bool; //~ ERROR casting `&'static str` as `bool` is invalid
+
+    let v = "hello" as bool;
+    //~^ ERROR casting `&'static str` as `bool` is invalid
+    //~| HELP consider using the `is_empty` method on `&'static str` to determine if it contains anything
 }