If suggestion would leave an empty line, delete it

Author: clubby789

compiler/rustc_errors/src/json.rs

@@ -479,14 +479,24 @@ impl DiagnosticSpan {
     }
 
     fn from_span_full(
-        span: Span,
+        mut span: Span,
         is_primary: bool,
         label: Option<String>,
         suggestion: Option<(&String, Applicability)>,
         mut backtrace: impl Iterator<Item = ExpnData>,
         je: &JsonEmitter,
     ) -> DiagnosticSpan {
         let start = je.sm.lookup_char_pos(span.lo());
+        // If this goes from the start of a line to the end and the replacement
+        // is an empty string, increase the length to include the newline so we don't
+        // leave an empty line
+        if start.col.0 == 0
+            && suggestion.map_or(false, |(s, _)| s.is_empty())
+            && let Ok(after) = je.sm.span_to_next_source(span)
+            && after.starts_with('\n')
+        {
+            span = span.with_hi(span.hi() + rustc_span::BytePos(1));
+        }
         let end = je.sm.lookup_char_pos(span.hi());
         let backtrace_step = backtrace.next().map(|bt| {
             let call_site = Self::from_span_full(bt.call_site, false, None, None, backtrace, je);

tests/ui/associated-types/impl-wf-cycle-6.fixed

@@ -19,7 +19,6 @@ impl Grault for () {
 
 impl<T: Grault> Grault for (T,)
 //~^ ERROR overflow evaluating the requirement `<(T,) as Grault>::A == _`
-
 {
     type A = ();
     type B = bool;

tests/ui/generics/generic-no-mangle.fixed

@@ -2,10 +2,8 @@
 
 #![deny(no_mangle_generic_items)]
 
-
 pub fn foo<T>() {} //~ ERROR functions generic over types or consts must be mangled
 
-
 pub extern "C" fn bar<T>() {} //~ ERROR functions generic over types or consts must be mangled
 
 #[no_mangle]

tests/ui/imports/issue-52891.fixed

@@ -27,10 +27,8 @@ use issue_52891::{l,
 use issue_52891::a::inner;
 use issue_52891::b::inner as other_inner; //~ ERROR `inner` is defined multiple times
 
-
 //~^ ERROR `issue_52891` is defined multiple times
 
-
 #[macro_use]
 use issue_52891::n; //~ ERROR `n` is defined multiple times
 

tests/ui/imports/unused-import-issue-87973.fixed

@@ -2,7 +2,6 @@
 #![deny(unused_imports)]
 
 // Check that attributes get removed too. See #87973.
-
 //~^ ERROR unused import
 
 fn main() {}

tests/ui/lazy-type-alias/leading-where-clause.fixed

@@ -6,7 +6,6 @@
 // Check that we *reject* leading where-clauses on lazy type aliases.
 
 type Alias<T>
-
 = T where String: From<T>;
 //~^^^ ERROR where clauses are not allowed before the type for type aliases
 

tests/ui/lint/suggestions.fixed

@@ -7,7 +7,6 @@
 //~^ ERROR const items should never be `#[no_mangle]`
 //~| HELP try a static value
 
-
 //~^ HELP remove this attribute
 pub fn defiant<T>(_t: T) {}
 //~^ WARN functions generic over types or consts must be mangled

tests/ui/lint/unused/import_remove_line.fixed

@@ -0,0 +1,11 @@
+// run-rustfix
+// check-pass
+
+#![crate_type = "lib"]
+#![warn(unused_imports)]
+
+//~^ WARN unused imports
+//~^ WARN unused import
+
+//~^ WARN unused import
+//~| WARN unused import

tests/ui/lint/unused/import_remove_line.rs

@@ -0,0 +1,13 @@
+// run-rustfix
+// check-pass
+
+#![crate_type = "lib"]
+#![warn(unused_imports)]
+
+use std::time::{Duration, Instant};
+//~^ WARN unused imports
+use std::time::SystemTime;
+//~^ WARN unused import
+use std::time::SystemTimeError;use std::time::TryFromFloatSecsError;
+//~^ WARN unused import
+//~| WARN unused import

tests/ui/lint/unused/import_remove_line.stderr

@@ -0,0 +1,32 @@
+warning: unused imports: `Duration`, `Instant`
+  --> $DIR/import_remove_line.rs:7:17
+   |
+LL | use std::time::{Duration, Instant};
+   |                 ^^^^^^^^  ^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/import_remove_line.rs:5:9
+   |
+LL | #![warn(unused_imports)]
+   |         ^^^^^^^^^^^^^^
+
+warning: unused import: `std::time::SystemTime`
+  --> $DIR/import_remove_line.rs:9:5
+   |
+LL | use std::time::SystemTime;
+   |     ^^^^^^^^^^^^^^^^^^^^^
+
+warning: unused import: `std::time::SystemTimeError`
+  --> $DIR/import_remove_line.rs:11:5
+   |
+LL | use std::time::SystemTimeError;use std::time::TryFromFloatSecsError;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: unused import: `std::time::TryFromFloatSecsError`
+  --> $DIR/import_remove_line.rs:11:36
+   |
+LL | use std::time::SystemTimeError;use std::time::TryFromFloatSecsError;
+   |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: 4 warnings emitted
+

tests/ui/resolve/resolve-conflict-import-vs-import.fixed

@@ -2,7 +2,6 @@
 
 #[allow(unused_imports)]
 use std::mem::transmute;
-
 //~^ ERROR the name `transmute` is defined multiple times
 
 fn main() {

tests/ui/rust-2018/extern-crate-idiomatic-in-2018.fixed

@@ -9,7 +9,6 @@
 #![deny(rust_2018_idioms)]
 #![allow(dead_code)]
 
-
 //~^ ERROR unused extern crate
 
 // Shouldn't suggest changing to `use`, as `bar`

tests/ui/rust-2018/issue-54400-unused-extern-crate-attr-span.fixed

@@ -8,7 +8,6 @@
 
 // The suggestion span should include the attribute.
 
-
 //~^ ERROR unused extern crate
 
 fn main() {}