diff options
4 files changed, 81 insertions, 1 deletions
diff --git a/src/librustc_mir_build/hair/pattern/check_match.rs b/src/librustc_mir_build/hair/pattern/check_match.rs index 6fc447a87f5..4bfb6cccbcb 100644 --- a/src/librustc_mir_build/hair/pattern/check_match.rs +++ b/src/librustc_mir_build/hair/pattern/check_match.rs @@ -12,6 +12,7 @@ use rustc_hir::def_id::DefId; use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor}; use rustc_hir::{HirId, Pat}; use rustc_middle::ty::{self, Ty, TyCtxt}; +use rustc_session::config::nightly_options; use rustc_session::lint::builtin::BINDINGS_WITH_VARIANT_NAME; use rustc_session::lint::builtin::{IRREFUTABLE_LET_PATTERNS, UNREACHABLE_PATTERNS}; use rustc_session::parse::feature_err; @@ -487,9 +488,27 @@ fn check_exhaustive<'p, 'tcx>( adt_defined_here(cx, &mut err, scrut_ty, &witnesses); err.help( "ensure that all possible cases are being handled, \ - possibly by adding wildcards or more match arms", + possibly by adding wildcards or more match arms", ); err.note(&format!("the matched value is of type `{}`", scrut_ty)); + if (scrut_ty == cx.tcx.types.usize || scrut_ty == cx.tcx.types.isize) + && !is_empty_match + && witnesses.len() == 1 + && witnesses[0].is_wildcard() + { + err.note(&format!( + "`{}` does not have a fixed maximum value, \ + so a wildcard `_` is necessary to match exhaustively", + scrut_ty, + )); + if nightly_options::is_nightly_build() { + err.help(&format!( + "add `#![feature(precise_pointer_size_matching)]` \ + to the crate attributes to enable precise `{}` matching", + scrut_ty, + )); + } + } err.emit(); } diff --git a/src/test/ui/feature-gates/feature-gate-precise_pointer_size_matching.stderr b/src/test/ui/feature-gates/feature-gate-precise_pointer_size_matching.stderr index 6c5d0091c5a..c7a63e5d502 100644 --- a/src/test/ui/feature-gates/feature-gate-precise_pointer_size_matching.stderr +++ b/src/test/ui/feature-gates/feature-gate-precise_pointer_size_matching.stderr @@ -6,6 +6,8 @@ LL | match 0usize { | = help: ensure that all possible cases are being handled, possibly by adding wildcards or more match arms = note: the matched value is of type `usize` + = note: `usize` does not have a fixed maximum value, so a wildcard `_` is necessary to match exhaustively + = help: add `#![feature(precise_pointer_size_matching)]` to the crate attributes to enable precise `usize` matching error[E0004]: non-exhaustive patterns: `_` not covered --> $DIR/feature-gate-precise_pointer_size_matching.rs:10:11 @@ -15,6 +17,8 @@ LL | match 0isize { | = help: ensure that all possible cases are being handled, possibly by adding wildcards or more match arms = note: the matched value is of type `isize` + = note: `isize` does not have a fixed maximum value, so a wildcard `_` is necessary to match exhaustively + = help: add `#![feature(precise_pointer_size_matching)]` to the crate attributes to enable precise `isize` matching error: aborting due to 2 previous errors diff --git a/src/test/ui/pattern/usefulness/non-exhaustive-pattern-pointer-size-int.rs b/src/test/ui/pattern/usefulness/non-exhaustive-pattern-pointer-size-int.rs new file mode 100644 index 00000000000..0c52876e21f --- /dev/null +++ b/src/test/ui/pattern/usefulness/non-exhaustive-pattern-pointer-size-int.rs @@ -0,0 +1,23 @@ +use std::{usize, isize}; + +fn main() { + match 0usize { + //~^ ERROR non-exhaustive patterns + //~| NOTE pattern `_` not covered + //~| NOTE the matched value is of type `usize` + //~| NOTE `usize` does not have a fixed maximum value + 0 ..= usize::MAX => {} + } + + match 0isize { + //~^ ERROR non-exhaustive patterns + //~| NOTE pattern `_` not covered + //~| NOTE the matched value is of type `isize` + //~| NOTE `isize` does not have a fixed maximum value + isize::MIN ..= isize::MAX => {} + } + + match 7usize {} + //~^ ERROR non-exhaustive patterns + //~| NOTE the matched value is of type `usize` +} diff --git a/src/test/ui/pattern/usefulness/non-exhaustive-pattern-pointer-size-int.stderr b/src/test/ui/pattern/usefulness/non-exhaustive-pattern-pointer-size-int.stderr new file mode 100644 index 00000000000..d0aa452fd38 --- /dev/null +++ b/src/test/ui/pattern/usefulness/non-exhaustive-pattern-pointer-size-int.stderr @@ -0,0 +1,34 @@ +error[E0004]: non-exhaustive patterns: `_` not covered + --> $DIR/non-exhaustive-pattern-pointer-size-int.rs:4:11 + | +LL | match 0usize { + | ^^^^^^ pattern `_` not covered + | + = help: ensure that all possible cases are being handled, possibly by adding wildcards or more match arms + = note: the matched value is of type `usize` + = note: `usize` does not have a fixed maximum value, so a wildcard `_` is necessary to match exhaustively + = help: add `#![feature(precise_pointer_size_matching)]` to the crate attributes to enable precise `usize` matching + +error[E0004]: non-exhaustive patterns: `_` not covered + --> $DIR/non-exhaustive-pattern-pointer-size-int.rs:12:11 + | +LL | match 0isize { + | ^^^^^^ pattern `_` not covered + | + = help: ensure that all possible cases are being handled, possibly by adding wildcards or more match arms + = note: the matched value is of type `isize` + = note: `isize` does not have a fixed maximum value, so a wildcard `_` is necessary to match exhaustively + = help: add `#![feature(precise_pointer_size_matching)]` to the crate attributes to enable precise `isize` matching + +error[E0004]: non-exhaustive patterns: type `usize` is non-empty + --> $DIR/non-exhaustive-pattern-pointer-size-int.rs:20:11 + | +LL | match 7usize {} + | ^^^^^^ + | + = help: ensure that all possible cases are being handled, possibly by adding wildcards or more match arms + = note: the matched value is of type `usize` + +error: aborting due to 3 previous errors + +For more information about this error, try `rustc --explain E0004`. |