Rollup merge of #61380 - varkor:expected-usize-got-param, r=eddyb

Fix some issues with `unwrap_usize` instead of `assert_usize`

Fixes https://github.com/rust-lang/rust/issues/61337.
Fixes https://github.com/rust-lang/rust/issues/61341.
Fixes https://github.com/rust-lang/rust/issues/61422.

r? @eddyb

15 files changed, 160 insertions, 28 deletions

diff --git a/src/librustc/traits/error_reporting.rs b/src/librustc/traits/error_reporting.rs
index a29b173880a..95312d55b3b 100644
--- a/src/librustc/traits/error_reporting.rs
+++ b/src/librustc/traits/error_reporting.rs
@@ -914,8 +914,11 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             }
 
             // already reported in the query
-            ConstEvalFailure(_) => {
-                self.tcx.sess.delay_span_bug(span, "constant in type had an ignored error");
+            ConstEvalFailure(err) => {
+                self.tcx.sess.delay_span_bug(
+                    span,
+                    &format!("constant in type had an ignored error: {:?}", err),
+                );
                 return;
             }
 
diff --git a/src/librustc/ty/layout.rs b/src/librustc/ty/layout.rs
index 6d7b0926c7a..6415122dd39 100644
--- a/src/librustc/ty/layout.rs
+++ b/src/librustc/ty/layout.rs
@@ -549,8 +549,8 @@ impl<'a, 'tcx> LayoutCx<'tcx, TyCtxt<'a, 'tcx, 'tcx>> {
                     }
                 }
 
+                let count = count.assert_usize(tcx).ok_or(LayoutError::Unknown(ty))?;
                 let element = self.layout_of(element)?;
-                let count = count.unwrap_usize(tcx);
                 let size = element.size.checked_mul(count, dl)
                     .ok_or(LayoutError::SizeOverflow(ty))?;
 
diff --git a/src/librustc_codegen_llvm/debuginfo/metadata.rs b/src/librustc_codegen_llvm/debuginfo/metadata.rs
index b000628a3f7..42bd790ca2e 100644
--- a/src/librustc_codegen_llvm/debuginfo/metadata.rs
+++ b/src/librustc_codegen_llvm/debuginfo/metadata.rs
@@ -342,9 +342,7 @@ fn fixed_vec_metadata(
     let (size, align) = cx.size_and_align_of(array_or_slice_type);
 
     let upper_bound = match array_or_slice_type.sty {
-        ty::Array(_, len) => {
-            len.unwrap_usize(cx.tcx) as c_longlong
-        }
+        ty::Array(_, len) => len.unwrap_usize(cx.tcx) as c_longlong,
         _ => -1
     };
 
diff --git a/src/librustc_mir/borrow_check/places_conflict.rs b/src/librustc_mir/borrow_check/places_conflict.rs
index 74da3f96653..8aa27eef72a 100644
--- a/src/librustc_mir/borrow_check/places_conflict.rs
+++ b/src/librustc_mir/borrow_check/places_conflict.rs
@@ -332,8 +332,8 @@ fn place_base_conflict<'a, 'gcx: 'tcx, 'tcx>(
                 },
                 (StaticKind::Promoted(promoted_1), StaticKind::Promoted(promoted_2)) => {
                     if promoted_1 == promoted_2 {
-                        if let ty::Array(_, size) = s1.ty.sty {
-                            if size.unwrap_usize(tcx) == 0 {
+                        if let ty::Array(_, len) = s1.ty.sty {
+                            if let Some(0) = len.assert_usize(tcx) {
                                 // Ignore conflicts with promoted [T; 0].
                                 debug!("place_element_conflict: IGNORE-LEN-0-PROMOTED");
                                 return Overlap::Disjoint;
diff --git a/src/librustc_mir/transform/qualify_consts.rs b/src/librustc_mir/transform/qualify_consts.rs
index a416792101f..fe94181047f 100644
--- a/src/librustc_mir/transform/qualify_consts.rs
+++ b/src/librustc_mir/transform/qualify_consts.rs
@@ -316,8 +316,9 @@ impl Qualif for HasMutInterior {
                     } else if let ty::Array(_, len) = ty.sty {
                         // FIXME(eddyb) the `cx.mode == Mode::Fn` condition
                         // seems unnecessary, given that this is merely a ZST.
-                        if !(len.unwrap_usize(cx.tcx) == 0 && cx.mode == Mode::Fn) {
-                            return true;
+                        match len.assert_usize(cx.tcx) {
+                            Some(0) if cx.mode == Mode::Fn => {},
+                            _ => return true,
                         }
                     } else {
                         return true;
diff --git a/src/librustc_typeck/check/_match.rs b/src/librustc_typeck/check/_match.rs
index 5cd95a9d834..64e2eedd721 100644
--- a/src/librustc_typeck/check/_match.rs
+++ b/src/librustc_typeck/check/_match.rs
@@ -400,27 +400,36 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                 let expected_ty = self.structurally_resolved_type(pat.span, expected);
                 let (inner_ty, slice_ty) = match expected_ty.sty {
                     ty::Array(inner_ty, size) => {
-                        let size = size.unwrap_usize(tcx);
-                        let min_len = before.len() as u64 + after.len() as u64;
-                        if slice.is_none() {
-                            if min_len != size {
-                                struct_span_err!(
-                                    tcx.sess, pat.span, E0527,
-                                    "pattern requires {} elements but array has {}",
-                                    min_len, size)
-                                    .span_label(pat.span, format!("expected {} elements", size))
+                        if let Some(size) = size.assert_usize(tcx) {
+                            let min_len = before.len() as u64 + after.len() as u64;
+                            if slice.is_none() {
+                                if min_len != size {
+                                    struct_span_err!(
+                                        tcx.sess, pat.span, E0527,
+                                        "pattern requires {} elements but array has {}",
+                                        min_len, size)
+                                        .span_label(pat.span, format!("expected {} elements", size))
+                                        .emit();
+                                }
+                                (inner_ty, tcx.types.err)
+                            } else if let Some(rest) = size.checked_sub(min_len) {
+                                (inner_ty, tcx.mk_array(inner_ty, rest))
+                            } else {
+                                struct_span_err!(tcx.sess, pat.span, E0528,
+                                        "pattern requires at least {} elements but array has {}",
+                                        min_len, size)
+                                    .span_label(pat.span,
+                                        format!("pattern cannot match array of {} elements", size))
                                     .emit();
+                                (inner_ty, tcx.types.err)
                             }
-                            (inner_ty, tcx.types.err)
-                        } else if let Some(rest) = size.checked_sub(min_len) {
-                            (inner_ty, tcx.mk_array(inner_ty, rest))
                         } else {
-                            struct_span_err!(tcx.sess, pat.span, E0528,
-                                    "pattern requires at least {} elements but array has {}",
-                                    min_len, size)
-                                .span_label(pat.span,
-                                    format!("pattern cannot match array of {} elements", size))
-                                .emit();
+                            struct_span_err!(
+                                tcx.sess,
+                                pat.span,
+                                E0730,
+                                "cannot pattern-match on an array without a fixed length",
+                            ).emit();
                             (inner_ty, tcx.types.err)
                         }
                     }
diff --git a/src/librustc_typeck/error_codes.rs b/src/librustc_typeck/error_codes.rs
index 6dd3c0113cd..b5a50f43875 100644
--- a/src/librustc_typeck/error_codes.rs
+++ b/src/librustc_typeck/error_codes.rs
@@ -4648,6 +4648,38 @@ fn make_recursive_type() -> impl Sized {
 ```
 "##,
 
+E0730: r##"
+An array without a fixed length was pattern-matched.
+
+Example of erroneous code:
+
+```compile_fail,E0730
+#![feature(const_generics)]
+
+fn is_123<const N: usize>(x: [u32; N]) -> bool {
+    match x {
+        [1, 2, 3] => true, // error: cannot pattern-match on an
+                           //        array without a fixed length
+        _ => false
+    }
+}
+```
+
+Ensure that the pattern is consistent with the size of the matched
+array. Additional elements can be matched with `..`:
+
+```
+#![feature(slice_patterns)]
+
+let r = &[1, 2, 3, 4];
+match r {
+    &[a, b, ..] => { // ok!
+        println!("a={}, b={}", a, b);
+    }
+}
+```
+"##,
+
 }
 
 register_diagnostics! {
diff --git a/src/test/ui/const-generics/issue-61422.rs b/src/test/ui/const-generics/issue-61422.rs
new file mode 100644
index 00000000000..3ccf38e5619
--- /dev/null
+++ b/src/test/ui/const-generics/issue-61422.rs
@@ -0,0 +1,15 @@
+// run-pass
+
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+use std::mem;
+
+fn foo<const SIZE: usize>() {
+    let arr: [u8; SIZE] = unsafe {
+        let mut array: [u8; SIZE] = mem::uninitialized();
+        array
+    };
+}
+
+fn main() {}
diff --git a/src/test/ui/const-generics/issue-61422.stderr b/src/test/ui/const-generics/issue-61422.stderr
new file mode 100644
index 00000000000..4cb76ec4fe1
--- /dev/null
+++ b/src/test/ui/const-generics/issue-61422.stderr
@@ -0,0 +1,6 @@
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+  --> $DIR/issue-61422.rs:3:12
+   |
+LL | #![feature(const_generics)]
+   |            ^^^^^^^^^^^^^^
+
diff --git a/src/test/ui/const-generics/mut-ref-const-param-array.rs b/src/test/ui/const-generics/mut-ref-const-param-array.rs
new file mode 100644
index 00000000000..f930fb87963
--- /dev/null
+++ b/src/test/ui/const-generics/mut-ref-const-param-array.rs
@@ -0,0 +1,19 @@
+// run-pass
+
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+use std::ops::AddAssign;
+
+fn inc<T: AddAssign + Clone, const N: usize>(v: &mut [T; N]) -> &mut [T; N] {
+    for x in v.iter_mut() {
+        *x += x.clone();
+    }
+    v
+}
+
+fn main() {
+    let mut v = [1, 2, 3];
+    inc(&mut v);
+    assert_eq!(v, [2, 4, 6]);
+}
diff --git a/src/test/ui/const-generics/mut-ref-const-param-array.stderr b/src/test/ui/const-generics/mut-ref-const-param-array.stderr
new file mode 100644
index 00000000000..261d3578a11
--- /dev/null
+++ b/src/test/ui/const-generics/mut-ref-const-param-array.stderr
@@ -0,0 +1,6 @@
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+  --> $DIR/mut-ref-const-param-array.rs:3:12
+   |
+LL | #![feature(const_generics)]
+   |            ^^^^^^^^^^^^^^
+
diff --git a/src/test/ui/const-generics/transparent-maybeunit-array-wrapper.rs b/src/test/ui/const-generics/transparent-maybeunit-array-wrapper.rs
new file mode 100644
index 00000000000..794048174f9
--- /dev/null
+++ b/src/test/ui/const-generics/transparent-maybeunit-array-wrapper.rs
@@ -0,0 +1,11 @@
+// run-pass
+
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+use std::mem::MaybeUninit;
+
+#[repr(transparent)]
+pub struct MaybeUninitWrapper<const N: usize>(MaybeUninit<[u64; N]>);
+
+fn main() {}
diff --git a/src/test/ui/const-generics/transparent-maybeunit-array-wrapper.stderr b/src/test/ui/const-generics/transparent-maybeunit-array-wrapper.stderr
new file mode 100644
index 00000000000..661bbd113bc
--- /dev/null
+++ b/src/test/ui/const-generics/transparent-maybeunit-array-wrapper.stderr
@@ -0,0 +1,6 @@
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+  --> $DIR/transparent-maybeunit-array-wrapper.rs:3:12
+   |
+LL | #![feature(const_generics)]
+   |            ^^^^^^^^^^^^^^
+
diff --git a/src/test/ui/error-codes/E0730.rs b/src/test/ui/error-codes/E0730.rs
new file mode 100644
index 00000000000..e5048d6e6e3
--- /dev/null
+++ b/src/test/ui/error-codes/E0730.rs
@@ -0,0 +1,11 @@
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+fn is_123<const N: usize>(x: [u32; N]) -> bool {
+    match x {
+        [1, 2, 3] => true, //~ ERROR cannot pattern-match on an array without a fixed length
+        _ => false
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/error-codes/E0730.stderr b/src/test/ui/error-codes/E0730.stderr
new file mode 100644
index 00000000000..f9281262bb7
--- /dev/null
+++ b/src/test/ui/error-codes/E0730.stderr
@@ -0,0 +1,15 @@
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+  --> $DIR/E0730.rs:1:12
+   |
+LL | #![feature(const_generics)]
+   |            ^^^^^^^^^^^^^^
+
+error[E0730]: cannot pattern-match on an array without a fixed length
+  --> $DIR/E0730.rs:6:9
+   |
+LL |         [1, 2, 3] => true,
+   |         ^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0730`.