Auto merge of #47064 - kennytm:force-trailing-newlines, r=estebank

Add a tidy check for missing or too many trailing newlines.

I've noticed recently there are lots of review comments requesting to fix trailing newlines. If this is going to be an official style here, it's better to let the CI do this repetitive check.

src/liballoc/tests/cow_str.rs

@@ -148,4 +148,4 @@ fn check_cow_clone_from() {
     let c2: Cow<str> = Cow::Owned(s);
     c1.clone_from(&c2);
     assert!(c1.into_owned().capacity() >= 25);
-}
+}

src/libcore/tests/ops.rs

@@ -67,4 +67,4 @@ fn test_range_inclusive() {
     r = RangeInclusive { start: 1, end: -1 };
     assert_eq!(r.size_hint(), (0, Some(0)));
     assert_eq!(r.next(), None);
-}
+}

src/libserialize/collection_impls.rs

@@ -241,4 +241,4 @@ impl<T: Decodable> Decodable for Arc<[T]> {
             Ok(vec.into())
         })
     }
-}
+}

src/test/codegen/prefetch.rs

@@ -71,5 +71,3 @@ pub fn check_prefetch_write_instruction(data: &[i8]) {
         prefetch_write_instruction(data.as_ptr(), 3);
     }
 }
-
-

src/test/compile-fail/E0004.rs

@@ -19,4 +19,4 @@ fn main() {
     match x { //~ ERROR E0004
         Terminator::TalkToMyHand => {}
     }
-}
+}

src/test/compile-fail/duplicate_entry_error.rs

@@ -20,4 +20,4 @@ fn panic_fmt() -> ! {
     loop {}
 }
 
-fn main() {}
+fn main() {}

src/test/compile-fail/float-int-invalid-const-cast.rs

@@ -58,4 +58,4 @@ fn main() {
     { const X: u32 = 4294967296. as u32; force(X); } //~ ERROR constant evaluation error
     { const X: u128 = 1e40 as u128; force(X); } //~ ERROR constant evaluation error
     { const X: i128 = 1e40 as i128; force(X); } //~ ERROR constant evaluation error
-}
+}

src/test/compile-fail/issue-28848.rs

@@ -20,4 +20,4 @@ pub fn foo<'a, 'b>(u: &'b ()) -> &'a () {
     Foo::<'a, 'b>::xmute(u) //~ ERROR lifetime bound not satisfied
 }
 
-fn main() {}
+fn main() {}

src/test/compile-fail/never-assign-wrong-type.rs

@@ -16,5 +16,3 @@
 fn main() {
     let x: ! = "hello"; //~ ERROR mismatched types
 }
-
-

src/test/compile-fail/range_inclusive_gate.rs

@@ -19,5 +19,3 @@ pub fn main() {
     //~| ERROR core_intrinsics
     //~| ERROR core_intrinsics
 }
-
-

src/test/compile-fail/useless_comment.rs

@@ -27,4 +27,4 @@ fn foo() {
 
 fn main() {
     foo();
-}
+}

src/test/incremental/hashes/enum_defs.rs

@@ -651,5 +651,3 @@ mod change_trait_bound_indirectly_where {
         Variant1(T)
     }
 }
-
-

src/test/incremental/hashes/inline_asm.rs

@@ -236,6 +236,3 @@ pub fn change_options(_a: i32) -> i32 {
     }
     _out
 }
-
-
-

src/test/mir-opt/return_an_array.rs

@@ -15,4 +15,4 @@ fn foo() -> [u8; 1024] {
         return x;
 }
 
-fn main() { }
+fn main() { }

src/test/parse-fail/issue-37113.rs

@@ -18,4 +18,4 @@ macro_rules! test_macro {
 
 fn main() {
     test_macro!(String,);
-}
+}

src/test/parse-fail/range_inclusive_gate.rs

@@ -72,5 +72,3 @@ pub fn main() {
     o!(); // not allowed in macros that output cfgs
     p!(); // not allowed in cfg'ed macros that output cfgs
 }
-
-

src/test/run-fail/return-never-coerce.rs

@@ -24,5 +24,3 @@ fn main() {
     let x: i32 = call_another_fn(wub);
     let y: u32 = wub();
 }
-
-

src/test/run-make/a-b-a-linker-guard/a.rs

@@ -16,5 +16,3 @@ pub fn foo(x: u32) { }
 
 #[cfg(y)]
 pub fn foo(x: i32) { }
-
-

src/test/run-make/reproducible-build/reproducible-build.rs

@@ -124,5 +124,3 @@ fn main() {
 
     TupleStruct(1, 2, 3, 4).bar();
 }
-
-

src/test/run-pass/abi-sysv64-register-usage.rs

@@ -102,4 +102,4 @@ pub fn main() {
 }
 
 #[cfg(not(target_arch = "x86_64"))]
-pub fn main() {}
+pub fn main() {}

src/test/run-pass/auxiliary/issue_42007_s.rs

@@ -11,4 +11,4 @@
 #[repr(u8)]
 pub enum E {
     B = 1 as u8,
-}
+}

src/test/run-pass/for-loop-mut-ref-element.rs

@@ -12,4 +12,4 @@
 
 fn main() {
     for ref mut _a in std::iter::once(true) {}
-}
+}

src/test/run-pass/generator/borrow-in-tail-expr.rs

@@ -16,4 +16,4 @@ fn main() {
         let a = String::new();
         a.len()
     };
-}
+}

src/test/run-pass/generator/match-bindings.rs

@@ -27,4 +27,4 @@ fn main() {
             yield;
         }
     };
-}
+}

src/test/run-pass/generator/yield-subtype.rs

@@ -20,4 +20,4 @@ fn bar<'a>() {
     };
 }
 
-fn main() {}
+fn main() {}

src/test/run-pass/issue-22066.rs

@@ -18,4 +18,4 @@ pub trait LineFormatter<'a> {
     }
 }
 
-fn main() {}
+fn main() {}

src/test/run-pass/issue-32292.rs

@@ -15,4 +15,4 @@ struct Foo;
 
 fn main() {
     let _ = Foo;
-}
+}

src/test/run-pass/issue-33992.rs

@@ -37,4 +37,4 @@ pub static TEST7: bool = true;
 #[linkage = "weak_odr"]
 pub static TEST8: bool = true;
 
-fn main() {}
+fn main() {}

src/test/run-pass/issue-35376.rs

@@ -48,4 +48,4 @@ pub struct Handle;
 
 impl Beta for Handle {
     type Event = ();
-}
+}

src/test/run-pass/optimization-fuel-1.rs

@@ -22,5 +22,3 @@ fn main() {
         +(size_of::<S2>() == 4) as usize;
     assert_eq!(optimized, 1);
 }
-
-

src/test/rustdoc/doc-cfg.rs

@@ -44,4 +44,4 @@ pub mod unix_only {
     impl ArmOnly for super::Portable {
         fn unix_and_arm_only_function() {}
     }
-}
+}

src/test/ui-fulldeps/update-references.sh

@@ -46,5 +46,3 @@ while [[ "$1" != "" ]]; do
         cp $BUILD_DIR/$STDERR_NAME $MYDIR/$STDERR_NAME
     fi
 done
-
-

src/test/ui/in-band-lifetimes/single_use_lifetimes-4.rs

@@ -17,4 +17,4 @@ enum Bar<'x> { //~ ERROR lifetime name `'x` only used once
     Variant(&'x u32)
 }
 
-fn main() { }
+fn main() { }

src/test/ui/in-band-lifetimes/single_use_lifetimes.rs

@@ -13,4 +13,4 @@ fn deref<'x>(v: &'x u32) -> u32 { //~ ERROR lifetime name `'x` only used once
     *v
 }
 
-fn main() {}
+fn main() {}

src/test/ui/update-references.sh

@@ -46,5 +46,3 @@ while [[ "$1" != "" ]]; do
         cp $BUILD_DIR/$STDERR_NAME $MYDIR/$STDERR_NAME
     fi
 done
-
-

src/tools/tidy/src/style.rs

@@ -130,6 +130,7 @@ pub fn check(path: &Path, bad: &mut bool) {
         let skip_tab = contents.contains("ignore-tidy-tab");
         let skip_length = contents.contains("ignore-tidy-linelength");
         let skip_end_whitespace = contents.contains("ignore-tidy-end-whitespace");
+        let mut trailing_new_lines = 0;
         for (i, line) in contents.split("\n").enumerate() {
             let mut err = |msg: &str| {
                 tidy_error!(bad, "{}:{}: {}", file.display(), i + 1, msg);
@@ -161,10 +162,20 @@ pub fn check(path: &Path, bad: &mut bool) {
             if filename.ends_with(".cpp") && line.contains("llvm_unreachable") {
                 err(LLVM_UNREACHABLE_INFO);
             }
+            if line.is_empty() {
+                trailing_new_lines += 1;
+            } else {
+                trailing_new_lines = 0;
+            }
         }
         if !licenseck(file, &contents) {
             tidy_error!(bad, "{}: incorrect license", file.display());
         }
+        match trailing_new_lines {
+            0 => tidy_error!(bad, "{}: missing trailing newline", file.display()),
+            1 | 2 => {}
+            n => tidy_error!(bad, "{}: too many trailing newlines ({})", file.display(), n),
+        };
     })
 }