let expr_ty = self.resolve_type_vars_with_obligations(checked_ty);
let mut err = self.report_mismatched_types(&cause, expected, expr_ty, e);
- // If the expected type is an enum with any variants whose sole
- // field is of the found type, suggest such variants. See Issue
- // #42764.
+ // If the expected type is an enum (Issue #55250) with any variants whose
+ // sole field is of the found type, suggest such variants. (Issue #42764)
if let ty::Adt(expected_adt, substs) = expected.sty {
- let compatible_variants = expected_adt.variants
- .iter()
- .filter(|variant| variant.fields.len() == 1)
- .filter_map(|variant| {
- let sole_field = &variant.fields[0];
- let sole_field_ty = sole_field.ty(self.tcx, substs);
- if self.can_coerce(expr_ty, sole_field_ty) {
- let variant_path = self.tcx.item_path_str(variant.did);
- Some(variant_path.trim_left_matches("std::prelude::v1::").to_string())
- } else {
- None
+ if expected_adt.is_enum() {
+ let mut compatible_variants = expected_adt.variants
+ .iter()
+ .filter(|variant| variant.fields.len() == 1)
+ .filter_map(|variant| {
+ let sole_field = &variant.fields[0];
+ let sole_field_ty = sole_field.ty(self.tcx, substs);
+ if self.can_coerce(expr_ty, sole_field_ty) {
+ let variant_path = self.tcx.item_path_str(variant.did);
+ Some(variant_path.trim_left_matches("std::prelude::v1::").to_string())
+ } else {
+ None
+ }
+ }).peekable();
+
+ if compatible_variants.peek().is_some() {
+ let expr_text = print::to_string(print::NO_ANN, |s| s.print_expr(expr));
+ let suggestions = compatible_variants
+ .map(|v| format!("{}({})", v, expr_text)).collect::<Vec<_>>();
+ err.span_suggestions_with_applicability(
+ expr.span,
+ "try using a variant of the expected type",
+ suggestions,
+ Applicability::MaybeIncorrect,
+ );
}
- }).collect::<Vec<_>>();
-
- if !compatible_variants.is_empty() {
- let expr_text = print::to_string(print::NO_ANN, |s| s.print_expr(expr));
- let suggestions = compatible_variants.iter()
- .map(|v| format!("{}({})", v, expr_text)).collect::<Vec<_>>();
- err.span_suggestions_with_applicability(
- expr.span,
- "try using a variant of the expected type",
- suggestions,
- Applicability::MaybeIncorrect,
- );
}
}
};
if self.can_coerce(ref_ty, expected) {
if let Ok(src) = cm.span_to_snippet(sp) {
- let sugg_expr = match expr.node { // parenthesize if needed (Issue #46756)
+ let needs_parens = match expr.node {
+ // parenthesize if needed (Issue #46756)
hir::ExprKind::Cast(_, _) |
- hir::ExprKind::Binary(_, _, _) => format!("({})", src),
- _ => src,
+ hir::ExprKind::Binary(_, _, _) => true,
+ // parenthesize borrows of range literals (Issue #54505)
+ _ if self.is_range_literal(expr) => true,
+ _ => false,
};
+ let sugg_expr = if needs_parens {
+ format!("({})", src)
+ } else {
+ src
+ };
+
if let Some(sugg) = self.can_use_as_ref(expr) {
return Some(sugg);
}
None
}
+ /// This function checks if the specified expression is a built-in range literal.
+ /// (See: `LoweringContext::lower_expr()` in `src/librustc/hir/lowering.rs`).
+ fn is_range_literal(&self, expr: &hir::Expr) -> bool {
+ use hir::{Path, QPath, ExprKind, TyKind};
+
+ // We support `::std::ops::Range` and `::core::ops::Range` prefixes
+ let is_range_path = |path: &Path| {
+ let mut segs = path.segments.iter()
+ .map(|seg| seg.ident.as_str());
+
+ if let (Some(root), Some(std_core), Some(ops), Some(range), None) =
+ (segs.next(), segs.next(), segs.next(), segs.next(), segs.next())
+ {
+ // "{{root}}" is the equivalent of `::` prefix in Path
+ root == "{{root}}" && (std_core == "std" || std_core == "core")
+ && ops == "ops" && range.starts_with("Range")
+ } else {
+ false
+ }
+ };
+
+ let span_is_range_literal = |span: &Span| {
+ // Check whether a span corresponding to a range expression
+ // is a range literal, rather than an explicit struct or `new()` call.
+ let source_map = self.tcx.sess.source_map();
+ let end_point = source_map.end_point(*span);
+
+ if let Ok(end_string) = source_map.span_to_snippet(end_point) {
+ !(end_string.ends_with("}") || end_string.ends_with(")"))
+ } else {
+ false
+ }
+ };
+
+ match expr.node {
+ // All built-in range literals but `..=` and `..` desugar to Structs
+ ExprKind::Struct(QPath::Resolved(None, ref path), _, _) |
+ // `..` desugars to its struct path
+ ExprKind::Path(QPath::Resolved(None, ref path)) => {
+ return is_range_path(&path) && span_is_range_literal(&expr.span);
+ }
+
+ // `..=` desugars into `::std::ops::RangeInclusive::new(...)`
+ ExprKind::Call(ref func, _) => {
+ if let ExprKind::Path(QPath::TypeRelative(ref ty, ref segment)) = func.node {
+ if let TyKind::Path(QPath::Resolved(None, ref path)) = ty.node {
+ let call_to_new = segment.ident.as_str() == "new";
+
+ return is_range_path(&path) && span_is_range_literal(&expr.span)
+ && call_to_new;
+ }
+ }
+ }
+
+ _ => {}
+ }
+
+ false
+ }
+
pub fn check_for_cast(&self,
err: &mut DiagnosticBuilder<'tcx>,
expr: &hir::Expr,
projects / rust.git / blobdiff