Auto merge of rust-lang#8912 - Alexendoo:needless-late-init-ice, r=gi…

…raffate

needless_late_init: fix ICE when all branches return the never type

Fixes rust-lang#8911

When the assignment is done in a match guard or the if condition and all of the branches return the never type `assignment_suggestions` would return an empty `Vec` which caused the ICE. It now returns `None` in that scenario

Also moves some tests to the top of the file

changelog: ICE Fixes: [`needless_late_init`] rust-lang#8911

clippy_lints/src/needless_late_init.rs

@@ -194,14 +194,15 @@ fn assignment_suggestions<'tcx>(
         }))
         .collect::<Option<Vec<(Span, String)>>>()?;
 
-    let applicability = if suggestions.len() > 1 {
+    match suggestions.len() {
+        // All of `exprs` are never types
+        // https://github.com/rust-lang/rust-clippy/issues/8911
+        0 => None,
+        1 => Some((Applicability::MachineApplicable, suggestions)),
         // multiple suggestions don't work with rustfix in multipart_suggest
         // https://github.com/rust-lang/rustfix/issues/141
-        Applicability::Unspecified
-    } else {
-        Applicability::MachineApplicable
-    };
-    Some((applicability, suggestions))
+        _ => Some((Applicability::Unspecified, suggestions)),
+    }
 }
 
 struct Usage<'tcx> {

tests/ui/needless_late_init.fixed

@@ -3,6 +3,7 @@
 #![allow(
     unused,
     clippy::assign_op_pattern,
+    clippy::blocks_in_if_conditions,
     clippy::let_and_return,
     clippy::let_unit_value,
     clippy::nonminimal_bool
@@ -18,6 +19,22 @@ impl std::ops::Drop for SignificantDrop {
     }
 }
 
+fn simple() {
+
+    let a = "zero";
+
+
+
+    let b = 1;
+    let c = 2;
+
+
+    let d: usize = 1;
+
+
+    let e = format!("{}", d);
+}
+
 fn main() {
 
     let n = 1;
@@ -237,22 +254,20 @@ fn does_not_lint() {
     x = SignificantDrop;
 }
 
-mod fixable {
-    #![allow(dead_code)]
-
-    fn main() {
-
-        let a = "zero";
-
-
-
-        let b = 1;
-        let c = 2;
-
-
-        let d: usize = 1;
+#[rustfmt::skip]
+fn issue8911() -> u32 {
+    let x;
+    match 1 {
+        _ if { x = 1; false } => return 1,
+        _ => return 2,
+    }
 
-
-        let e = format!("{}", d);
+    let x;
+    if { x = 1; true } {
+        return 1;
+    } else {
+        return 2;
     }
+
+    3
 }

tests/ui/needless_late_init.rs

@@ -3,6 +3,7 @@
 #![allow(
     unused,
     clippy::assign_op_pattern,
+    clippy::blocks_in_if_conditions,
     clippy::let_and_return,
     clippy::let_unit_value,
     clippy::nonminimal_bool
@@ -18,6 +19,22 @@ impl std::ops::Drop for SignificantDrop {
     }
 }
 
+fn simple() {
+    let a;
+    a = "zero";
+
+    let b;
+    let c;
+    b = 1;
+    c = 2;
+
+    let d: usize;
+    d = 1;
+
+    let e;
+    e = format!("{}", d);
+}
+
 fn main() {
     let a;
     let n = 1;
@@ -237,22 +254,20 @@ fn does_not_lint() {
     x = SignificantDrop;
 }
 
-mod fixable {
-    #![allow(dead_code)]
-
-    fn main() {
-        let a;
-        a = "zero";
-
-        let b;
-        let c;
-        b = 1;
-        c = 2;
-
-        let d: usize;
-        d = 1;
+#[rustfmt::skip]
+fn issue8911() -> u32 {
+    let x;
+    match 1 {
+        _ if { x = 1; false } => return 1,
+        _ => return 2,
+    }
 
-        let e;
-        e = format!("{}", d);
+    let x;
+    if { x = 1; true } {
+        return 1;
+    } else {
+        return 2;
     }
+
+    3
 }