rustfmt tests/mir-opt.

The only non-obvious changes:
- `building/storage_live_dead_in_statics.rs` has a `#[rustfmt::skip]`
  attribute to avoid reformating a table of data.
- Two `.mir` files have slight changes involving line numbers.
- In `unusual_item_types.rs` an `EMIT_MIR` annotation is moved to
  outside a function, which is the usual spot, because `tidy` complains
  if such a comment is indented.

The commit also tweaks the comments in `rustfmt.toml`.

rustfmt.toml

@@ -10,17 +10,13 @@ ignore = [
     "/build-*/",
     "/vendor/",
 
-    # Some tests are not formatted, for multiple reasons:
-    # - some contain syntax errors that cause rustfmt to give an error
-    # - some UI tests are broken by different formatting
-    # - some require special comments in a particular position (e.g. `EMIT_MIR` comments)
+    # Some tests are not formatted, for various reasons.
     "/tests/codegen/simd-intrinsic/", # Many types like `u8x64` are better hand-formatted.
-    "/tests/crashes/",                # Many tests contain syntax errors.
-    "/tests/debuginfo/",              # Tests are somewhat sensitive to source code layout.
-    "/tests/incremental/",            # Tests are somewhat sensitive to source code layout.
-    "/tests/mir-opt/",
+    "/tests/crashes/",                # Many of these tests contain syntax errors.
+    "/tests/debuginfo/",              # These tests are somewhat sensitive to source code layout.
+    "/tests/incremental/",            # These tests are somewhat sensitive to source code layout.
     "/tests/pretty/",
-    "/tests/run-make/translation/test.rs", # Contains syntax errors.
+    "/tests/run-make/translation/test.rs", # This test contains syntax errors.
     "/tests/run-make-fulldeps/",
     "/tests/run-pass-valgrind/",
     "/tests/rustdoc/",

tests/mir-opt/address_of.rs

@@ -9,7 +9,7 @@ fn address_of_reborrow() {
     y as *const [i32; 10];
     y as *const dyn Send;
     y as *const [i32];
-    y as *const i32;            // This is a cast, not a coercion
+    y as *const i32; // This is a cast, not a coercion
 
     let p: *const _ = y;
     let p: *const [i32; 10] = y;

tests/mir-opt/array_index_is_temporary.rs

@@ -9,7 +9,6 @@ unsafe fn foo(z: *mut usize) -> u32 {
     99
 }
 
-
 // EMIT_MIR array_index_is_temporary.main.SimplifyCfg-pre-optimizations.after.mir
 fn main() {
     // CHECK-LABEL: fn main(

tests/mir-opt/building/custom/debuginfo.rs

@@ -27,7 +27,9 @@ fn numbered(i: (u32, i32)) {
     }
 }
 
-struct S { x: f32 }
+struct S {
+    x: f32,
+}
 
 // EMIT_MIR debuginfo.structured.built.after.mir
 #[custom_mir(dialect = "analysis", phase = "post-cleanup")]

tests/mir-opt/building/enum_cast.rs

@@ -5,21 +5,24 @@
 // EMIT_MIR enum_cast.far.built.after.mir
 
 enum Foo {
-    A
+    A,
 }
 
 enum Bar {
-    A, B
+    A,
+    B,
 }
 
 #[repr(u8)]
 enum Boo {
-    A, B
+    A,
+    B,
 }
 
 #[repr(i16)]
 enum Far {
-    A, B
+    A,
+    B,
 }
 
 fn foo(foo: Foo) -> usize {
@@ -40,7 +43,9 @@ fn far(far: Far) -> isize {
 
 // EMIT_MIR enum_cast.droppy.built.after.mir
 enum Droppy {
-    A, B, C
+    A,
+    B,
+    C,
 }
 
 impl Drop for Droppy {
@@ -82,12 +87,15 @@ fn unsigny(x: UnsignedAroundZero) -> u16 {
     x as u16
 }
 
-enum NotStartingAtZero { A = 4, B = 6, C = 8 }
+enum NotStartingAtZero {
+    A = 4,
+    B = 6,
+    C = 8,
+}
 
 // EMIT_MIR enum_cast.offsetty.built.after.mir
 fn offsetty(x: NotStartingAtZero) -> u32 {
     x as u32
 }
 
-fn main() {
-}
+fn main() {}

tests/mir-opt/building/logical_or_in_conditional.rs

@@ -30,9 +30,13 @@ fn test_or() {
 
 // EMIT_MIR logical_or_in_conditional.test_complex.built.after.mir
 fn test_complex() {
-    if let E::A(_) = E::f() && ((always_true() && Droppy(0).0 > 0) || Droppy(1).0 > 1) {}
+    if let E::A(_) = E::f()
+        && ((always_true() && Droppy(0).0 > 0) || Droppy(1).0 > 1)
+    {}
 
-    if !always_true() && let E::B = E::f() {}
+    if !always_true()
+        && let E::B = E::f()
+    {}
 }
 
 fn main() {

tests/mir-opt/building/match/simple_match.rs

@@ -1,7 +1,6 @@
 // skip-filecheck
 // Test that we don't generate unnecessarily large MIR for very simple matches
 
-
 // EMIT_MIR simple_match.match_bool.built.after.mir
 fn match_bool(x: bool) -> usize {
     match x {

tests/mir-opt/building/shifts.rs

@@ -3,19 +3,12 @@
 
 // EMIT_MIR shifts.shift_signed.built.after.mir
 fn shift_signed(small: i8, big: u128, a: i8, b: i32, c: i128) -> ([i8; 3], [u128; 3]) {
-    (
-        [small >> a, small >> b, small >> c],
-        [big << a, big << b, big << c],
-    )
+    ([small >> a, small >> b, small >> c], [big << a, big << b, big << c])
 }
 
 // EMIT_MIR shifts.shift_unsigned.built.after.mir
 fn shift_unsigned(small: u8, big: i128, a: u8, b: u32, c: u128) -> ([u8; 3], [i128; 3]) {
-    (
-        [small >> a, small >> b, small >> c],
-        [big << a, big << b, big << c],
-    )
+    ([small >> a, small >> b, small >> c], [big << a, big << b, big << c])
 }
 
-fn main() {
-}
+fn main() {}

tests/mir-opt/building/storage_live_dead_in_statics.rs

@@ -3,6 +3,7 @@
 // generate `StorageStart` or `StorageEnd` statements.
 
 // EMIT_MIR storage_live_dead_in_statics.XXX.built.after.mir
+#[rustfmt::skip]
 static XXX: &'static Foo = &Foo {
     tup: "hi",
     data: &[
@@ -20,13 +21,13 @@ static XXX: &'static Foo = &Foo {
         (0, 1), (0, 2), (0, 3),
         (0, 1), (0, 2), (0, 3),
         (0, 1), (0, 2), (0, 3),
-    ]
+    ],
 };
 
 #[derive(Debug)]
 struct Foo {
     tup: &'static str,
-    data: &'static [(u32, u32)]
+    data: &'static [(u32, u32)],
 }
 
 fn main() {

tests/mir-opt/const_prop/control_flow_simplification.rs

@@ -11,7 +11,7 @@ impl<This> NeedsDrop for This {}
 
 // EMIT_MIR control_flow_simplification.hello.GVN.diff
 // EMIT_MIR control_flow_simplification.hello.PreCodegen.before.mir
-fn hello<T>(){
+fn hello<T>() {
     if <bool>::NEEDS {
         panic!()
     }

tests/mir-opt/const_prop/invalid_constant.rs

@@ -8,7 +8,11 @@
 
 #[derive(Copy, Clone)]
 #[repr(u32)]
-enum E { A, B, C }
+enum E {
+    A,
+    B,
+    C,
+}
 
 #[derive(Copy, Clone)]
 enum Empty {}
@@ -39,7 +43,5 @@ fn main() {
 
     // A non-UTF-8 string slice. Regression test for #75763 and #78520.
     struct Str<const S: &'static str>;
-    let _non_utf8_str: Str::<{
-        unsafe { std::mem::transmute::<&[u8], &str>(&[0xC0, 0xC1, 0xF5]) }
-    }>;
+    let _non_utf8_str: Str<{ unsafe { std::mem::transmute::<&[u8], &str>(&[0xC0, 0xC1, 0xF5]) } }>;
 }

tests/mir-opt/const_prop/offset_of.rs

@@ -31,7 +31,7 @@ struct Delta<T> {
 enum Epsilon {
     A(u8, u16),
     B,
-    C { c: u32 }
+    C { c: u32 },
 }
 
 enum Zeta<T> {

tests/mir-opt/const_prop/pointer_expose_provenance.rs

@@ -2,7 +2,7 @@
 //@ test-mir-pass: GVN
 
 #[inline(never)]
-fn read(_: usize) { }
+fn read(_: usize) {}
 
 // EMIT_MIR pointer_expose_provenance.main.GVN.diff
 fn main() {

tests/mir-opt/const_prop/scalar_literal_propagation.rs

@@ -10,4 +10,4 @@ fn main() {
 }
 
 #[inline(never)]
-fn consume(_: u32) { }
+fn consume(_: u32) {}

tests/mir-opt/const_prop/switch_int.rs

@@ -3,7 +3,7 @@
 // EMIT_MIR_FOR_EACH_PANIC_STRATEGY
 
 #[inline(never)]
-fn foo(_: i32) { }
+fn foo(_: i32) {}
 
 // EMIT_MIR switch_int.main.GVN.diff
 // EMIT_MIR switch_int.main.SimplifyConstCondition-after-const-prop.diff

tests/mir-opt/const_prop/transmute.rs

@@ -45,7 +45,10 @@ pub unsafe fn undef_union_as_integer() -> u32 {
     // CHECK-LABEL: fn undef_union_as_integer(
     // CHECK: _1 = Union32 {
     // CHECK: _0 = move _1 as u32 (Transmute);
-    union Union32 { value: u32, unit: () }
+    union Union32 {
+        value: u32,
+        unit: (),
+    }
     unsafe { transmute(Union32 { unit: () }) }
 }
 

tests/mir-opt/const_prop/tuple_literal_propagation.rs

@@ -10,4 +10,4 @@ fn main() {
 }
 
 #[inline(never)]
-fn consume(_: (u32, u32)) { }
+fn consume(_: (u32, u32)) {}

tests/mir-opt/copy-prop/borrowed_local.rs

@@ -4,10 +4,12 @@
 #![feature(custom_mir, core_intrinsics, freeze)]
 #![allow(unused_assignments)]
 extern crate core;
-use core::marker::Freeze;
 use core::intrinsics::mir::*;
+use core::marker::Freeze;
 
-fn opaque(_: impl Sized) -> bool { true }
+fn opaque(_: impl Sized) -> bool {
+    true
+}
 
 fn cmp_ref(a: &u8, b: &u8) -> bool {
     std::ptr::eq(a as *const u8, b as *const u8)

tests/mir-opt/copy-prop/move_projection.rs

@@ -7,7 +7,9 @@
 extern crate core;
 use core::intrinsics::mir::*;
 
-fn opaque(_: impl Sized) -> bool { true }
+fn opaque(_: impl Sized) -> bool {
+    true
+}
 
 struct Foo(u8);
 

tests/mir-opt/dataflow-const-prop/enum.rs

@@ -8,7 +8,7 @@ use std::intrinsics::mir::*;
 #[derive(Copy, Clone)]
 enum E {
     V1(i32),
-    V2(i32)
+    V2(i32),
 }
 
 // EMIT_MIR enum.simple.DataflowConstProp.diff
@@ -23,7 +23,10 @@ fn simple() {
     // CHECK: switchInt(const 0_isize) -> [0: [[target_bb:bb.*]], 1: bb2, otherwise: bb1];
     // CHECK: [[target_bb]]: {
     // CHECK:     [[x]] = const 0_i32;
-    let x = match e { E::V1(x1) => x1, E::V2(x2) => x2 };
+    let x = match e {
+        E::V1(x1) => x1,
+        E::V2(x2) => x2,
+    };
 }
 
 // EMIT_MIR enum.constant.DataflowConstProp.diff
@@ -39,7 +42,10 @@ fn constant() {
     // CHECK: switchInt(const 0_isize) -> [0: [[target_bb:bb.*]], 1: bb2, otherwise: bb1];
     // CHECK: [[target_bb]]: {
     // CHECK:     [[x]] = const 0_i32;
-    let x = match e { E::V1(x1) => x1, E::V2(x2) => x2 };
+    let x = match e {
+        E::V1(x1) => x1,
+        E::V2(x2) => x2,
+    };
 }
 
 // EMIT_MIR enum.statics.DataflowConstProp.diff
@@ -58,7 +64,10 @@ fn statics() {
     // CHECK: switchInt(const 0_isize) -> [0: [[target_bb:bb.*]], 1: bb2, otherwise: bb1];
     // CHECK: [[target_bb]]: {
     // CHECK:     [[x1]] = const 0_i32;
-    let x1 = match e1 { E::V1(x11) => x11, E::V2(x12) => x12 };
+    let x1 = match e1 {
+        E::V1(x11) => x11,
+        E::V2(x12) => x12,
+    };
 
     static RC: &E = &E::V2(4);
 
@@ -72,7 +81,10 @@ fn statics() {
     // One is `_9 = &(*_12) and another is `_9 = _11`. It is different from what we can
     // get by printing MIR directly. It is better to check if there are any bugs in the
     // MIR passes around this stage.
-    let x2 = match e2 { E::V1(x21) => x21, E::V2(x22) => x22 };
+    let x2 = match e2 {
+        E::V1(x21) => x21,
+        E::V2(x22) => x22,
+    };
 }
 
 #[rustc_layout_scalar_valid_range_start(1)]
@@ -132,7 +144,10 @@ fn multiple(x: bool, i: u8) {
     // CHECK: [[x2]] = const 0_u8;
     // CHECK: [[some:_.*]] = (({{_.*}} as Some).0: u8)
     // CHECK: [[x2]] = [[some]];
-    let x2 = match e { Some(i) => i, None => 0 };
+    let x2 = match e {
+        Some(i) => i,
+        None => 0,
+    };
 
     // Therefore, `x2` should be `Top` here, and no replacement shall happen.
 

tests/mir-opt/dataflow-const-prop/mult_by_zero.rs

@@ -2,9 +2,9 @@
 
 // EMIT_MIR mult_by_zero.test.DataflowConstProp.diff
 // CHECK-LABEL: fn test(
-fn test(x : i32) -> i32 {
-  x * 0
-  // CHECK: _0 = const 0_i32;
+fn test(x: i32) -> i32 {
+    x * 0
+    // CHECK: _0 = const 0_i32;
 }
 
 fn main() {

tests/mir-opt/dataflow-const-prop/transmute.rs

@@ -45,7 +45,10 @@ pub unsafe fn undef_union_as_integer() -> u32 {
     // CHECK-LABEL: fn undef_union_as_integer(
     // CHECK: _1 = Union32 {
     // CHECK: _0 = move _1 as u32 (Transmute);
-    union Union32 { value: u32, unit: () }
+    union Union32 {
+        value: u32,
+        unit: (),
+    }
     unsafe { transmute(Union32 { unit: () }) }
 }
 

tests/mir-opt/derefer_complex_case.rs

@@ -4,5 +4,7 @@
 // EMIT_MIR_FOR_EACH_PANIC_STRATEGY
 
 fn main() {
-    for &foo in &[42, 43] { drop(foo) }
+    for &foo in &[42, 43] {
+        drop(foo)
+    }
 }