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`.

Author: nnethercote

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!()
     }