diff options
| -rw-r--r-- | compiler/rustc_hir_analysis/src/check/callee.rs | 126 | ||||
| -rw-r--r-- | src/test/ui/suggestions/fn-to-method.rs | 19 | ||||
| -rw-r--r-- | src/test/ui/suggestions/fn-to-method.stderr | 38 |
3 files changed, 177 insertions, 6 deletions
diff --git a/compiler/rustc_hir_analysis/src/check/callee.rs b/compiler/rustc_hir_analysis/src/check/callee.rs index cf69747e10a..a715ce5bee8 100644 --- a/compiler/rustc_hir_analysis/src/check/callee.rs +++ b/compiler/rustc_hir_analysis/src/check/callee.rs @@ -1,7 +1,9 @@ +use super::method::probe::{IsSuggestion, Mode, ProbeScope}; use super::method::MethodCallee; use super::{DefIdOrName, Expectation, FnCtxt, TupleArgumentsFlag}; use crate::type_error_struct; +use rustc_ast::util::parser::PREC_POSTFIX; use rustc_errors::{struct_span_err, Applicability, Diagnostic, StashKey}; use rustc_hir as hir; use rustc_hir::def::{self, Namespace, Res}; @@ -407,7 +409,21 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { .diagnostic() .steal_diagnostic(segment.ident.span, StashKey::CallIntoMethod) { - diag.emit(); + // Try suggesting `foo(a)` -> `a.foo()` if possible. + if let Some(ty) = + self.suggest_call_as_method( + &mut diag, + segment, + arg_exprs, + call_expr, + expected + ) + { + diag.emit(); + return ty; + } else { + diag.emit(); + } } self.report_invalid_callee(call_expr, callee_expr, callee_ty, arg_exprs); @@ -457,6 +473,105 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { fn_sig.output() } + /// Attempts to reinterpret `method(rcvr, args...)` as `method.rcvr(args...)` + /// and suggesting the fix if the method probe is successful. + fn suggest_call_as_method( + &self, + diag: &mut Diagnostic, + segment: &'tcx hir::PathSegment<'tcx>, + arg_exprs: &'tcx [hir::Expr<'tcx>], + call_expr: &'tcx hir::Expr<'tcx>, + expected: Expectation<'tcx>, + ) -> Option<Ty<'tcx>> { + if let [callee_expr, rest @ ..] = arg_exprs { + let callee_ty = self.check_expr(callee_expr); + // First, do a probe with `IsSuggestion(true)` to avoid emitting + // any strange errors. If it's successful, then we'll do a true + // method lookup. + let Ok(pick) = self + .probe_for_name( + call_expr.span, + Mode::MethodCall, + segment.ident, + IsSuggestion(true), + callee_ty, + call_expr.hir_id, + // We didn't record the in scope traits during late resolution + // so we need to probe AllTraits unfortunately + ProbeScope::AllTraits, + ) else { + return None; + }; + + let pick = self.confirm_method( + call_expr.span, + callee_expr, + call_expr, + callee_ty, + pick, + segment, + ); + if pick.illegal_sized_bound.is_some() { + return None; + } + + let up_to_rcvr_span = segment.ident.span.until(callee_expr.span); + let rest_span = callee_expr.span.shrink_to_hi().to(call_expr.span.shrink_to_hi()); + let rest_snippet = if let Some(first) = rest.first() { + self.tcx + .sess + .source_map() + .span_to_snippet(first.span.to(call_expr.span.shrink_to_hi())) + } else { + Ok(")".to_string()) + }; + + if let Ok(rest_snippet) = rest_snippet { + let sugg = if callee_expr.precedence().order() >= PREC_POSTFIX { + vec![ + (up_to_rcvr_span, "".to_string()), + (rest_span, format!(".{}({rest_snippet}", segment.ident)), + ] + } else { + vec![ + (up_to_rcvr_span, "(".to_string()), + (rest_span, format!(").{}({rest_snippet}", segment.ident)), + ] + }; + let self_ty = self.resolve_vars_if_possible(pick.callee.sig.inputs()[0]); + diag.multipart_suggestion( + format!( + "use the `.` operator to call the method `{}{}` on `{self_ty}`", + self.tcx + .associated_item(pick.callee.def_id) + .trait_container(self.tcx) + .map_or_else( + || String::new(), + |trait_def_id| self.tcx.def_path_str(trait_def_id) + "::" + ), + segment.ident + ), + sugg, + Applicability::MaybeIncorrect, + ); + + // Let's check the method fully now + let return_ty = self.check_method_argument_types( + segment.ident.span, + call_expr, + Ok(pick.callee), + rest, + TupleArgumentsFlag::DontTupleArguments, + expected, + ); + + return Some(return_ty); + } + } + + None + } + fn report_invalid_callee( &self, call_expr: &'tcx hir::Expr<'tcx>, @@ -475,10 +590,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { def::CtorOf::Struct => "struct", def::CtorOf::Variant => "enum variant", }; - let removal_span = - callee_expr.span.shrink_to_hi().to(call_expr.span.shrink_to_hi()); - unit_variant = - Some((removal_span, descr, rustc_hir_pretty::qpath_to_string(qpath))); + let removal_span = callee_expr.span.shrink_to_hi().to(call_expr.span.shrink_to_hi()); + unit_variant = Some((removal_span, descr, rustc_hir_pretty::qpath_to_string(qpath))); } let callee_ty = self.resolve_vars_if_possible(callee_ty); @@ -541,7 +654,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { }; if !self.maybe_suggest_bad_array_definition(&mut err, call_expr, callee_expr) { - if let Some((maybe_def, output_ty, _)) = self.extract_callable_info(callee_expr, callee_ty) + if let Some((maybe_def, output_ty, _)) = + self.extract_callable_info(callee_expr, callee_ty) && !self.type_is_sized_modulo_regions(self.param_env, output_ty, callee_expr.span) { let descr = match maybe_def { diff --git a/src/test/ui/suggestions/fn-to-method.rs b/src/test/ui/suggestions/fn-to-method.rs new file mode 100644 index 00000000000..9a35c3efc41 --- /dev/null +++ b/src/test/ui/suggestions/fn-to-method.rs @@ -0,0 +1,19 @@ +struct Foo; + +impl Foo { + fn bar(self) {} +} + +fn main() { + let x = cmp(&1, &2); + //~^ ERROR cannot find function `cmp` in this scope + //~| HELP use the `.` operator to call the method `Ord::cmp` on `&{integer}` + + let y = len([1, 2, 3]); + //~^ ERROR cannot find function `len` in this scope + //~| HELP use the `.` operator to call the method `len` on `&[{integer}]` + + let z = bar(Foo); + //~^ ERROR cannot find function `bar` in this scope + //~| HELP use the `.` operator to call the method `bar` on `Foo` +} diff --git a/src/test/ui/suggestions/fn-to-method.stderr b/src/test/ui/suggestions/fn-to-method.stderr new file mode 100644 index 00000000000..36c17e60d35 --- /dev/null +++ b/src/test/ui/suggestions/fn-to-method.stderr @@ -0,0 +1,38 @@ +error[E0425]: cannot find function `cmp` in this scope + --> $DIR/fn-to-method.rs:8:13 + | +LL | let x = cmp(&1, &2); + | ^^^ not found in this scope + | +help: use the `.` operator to call the method `Ord::cmp` on `&{integer}` + | +LL | let x = (&1).cmp(&2); + | ~ ~~~~~~~~~ + +error[E0425]: cannot find function `len` in this scope + --> $DIR/fn-to-method.rs:12:13 + | +LL | let y = len([1, 2, 3]); + | ^^^ not found in this scope + | +help: use the `.` operator to call the method `len` on `&[{integer}]` + | +LL - let y = len([1, 2, 3]); +LL + let y = [1, 2, 3].len(); + | + +error[E0425]: cannot find function `bar` in this scope + --> $DIR/fn-to-method.rs:16:13 + | +LL | let z = bar(Foo); + | ^^^ not found in this scope + | +help: use the `.` operator to call the method `bar` on `Foo` + | +LL - let z = bar(Foo); +LL + let z = Foo.bar(); + | + +error: aborting due to 3 previous errors + +For more information about this error, try `rustc --explain E0425`. |