fix(zero_repeat_side_effects): don't suggest unsuggestable types (rust-lang#15815)

Fixes rust-lang#14998

changelog: [`zero_repeat_side_effects`]: don't suggest unsuggestable
types

Author: Jarcho

clippy_lints/src/zero_repeat_side_effects.rs

@@ -6,6 +6,7 @@ use rustc_data_structures::packed::Pu128;
 use rustc_errors::Applicability;
 use rustc_hir::{ConstArgKind, ExprKind, Node};
 use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::IsSuggestable;
 use rustc_session::declare_lint_pass;
 
 declare_clippy_lint! {
@@ -72,6 +73,7 @@ fn inner_check(cx: &LateContext<'_>, expr: &'_ rustc_hir::Expr<'_>, inner_expr:
     // check if expr is a call or has a call inside it
     if inner_expr.can_have_side_effects() {
         let parent_hir_node = cx.tcx.parent_hir_node(expr.hir_id);
+        let inner_expr_ty = cx.typeck_results().expr_ty(inner_expr);
         let return_type = cx.typeck_results().expr_ty(expr);
 
         let inner_expr = snippet(cx, inner_expr.span.source_callsite(), "..");
@@ -94,18 +96,25 @@ fn inner_check(cx: &LateContext<'_>, expr: &'_ rustc_hir::Expr<'_>, inner_expr:
             ),
             _ => (expr.span, format!("{{ {inner_expr}; {vec}[] as {return_type} }}")),
         };
+        let span = span.source_callsite();
         span_lint_and_then(
             cx,
             ZERO_REPEAT_SIDE_EFFECTS,
-            span.source_callsite(),
+            span,
             "expression with side effects as the initial value in a zero-sized array initializer",
             |diag| {
-                diag.span_suggestion_verbose(
-                    span.source_callsite(),
-                    "consider performing the side effect separately",
-                    sugg,
-                    Applicability::Unspecified,
-                );
+                if (!inner_expr_ty.is_never() || cx.tcx.features().never_type())
+                    && return_type.is_suggestable(cx.tcx, true)
+                {
+                    diag.span_suggestion_verbose(
+                        span,
+                        "consider performing the side effect separately",
+                        sugg,
+                        Applicability::Unspecified,
+                    );
+                } else {
+                    diag.help("consider performing the side effect separately");
+                }
             },
         );
     }

tests/ui/zero_repeat_side_effects_never_pattern.fixed

@@ -0,0 +1,9 @@
+#![warn(clippy::zero_repeat_side_effects)]
+#![allow(clippy::diverging_sub_expression)]
+#![feature(never_type)]
+
+fn issue_14998() {
+    // nameable type thanks to `never_type` being enabled, suggest
+    panic!(); let _data: [!; 0] = [];
+    //~^ zero_repeat_side_effects
+}

tests/ui/zero_repeat_side_effects_never_pattern.rs

@@ -0,0 +1,9 @@
+#![warn(clippy::zero_repeat_side_effects)]
+#![allow(clippy::diverging_sub_expression)]
+#![feature(never_type)]
+
+fn issue_14998() {
+    // nameable type thanks to `never_type` being enabled, suggest
+    let _data = [panic!(); 0];
+    //~^ zero_repeat_side_effects
+}

tests/ui/zero_repeat_side_effects_never_pattern.stderr

@@ -0,0 +1,16 @@
+error: expression with side effects as the initial value in a zero-sized array initializer
+  --> tests/ui/zero_repeat_side_effects_never_pattern.rs:7:5
+   |
+LL |     let _data = [panic!(); 0];
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::zero-repeat-side-effects` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::zero_repeat_side_effects)]`
+help: consider performing the side effect separately
+   |
+LL -     let _data = [panic!(); 0];
+LL +     panic!(); let _data: [!; 0] = [];
+   |
+
+error: aborting due to 1 previous error
+

tests/ui/zero_repeat_side_effects_unfixable.rs

@@ -0,0 +1,13 @@
+//@no-rustfix
+#![warn(clippy::zero_repeat_side_effects)]
+#![expect(clippy::diverging_sub_expression)]
+
+fn issue_14998() {
+    // unnameable types, don't suggest
+    let _data = [|| 3i32; 0];
+    //~^ zero_repeat_side_effects
+
+    // unnameable type because `never_type` is not enabled, don't suggest
+    let _data = [panic!(); 0];
+    //~^ zero_repeat_side_effects
+}

tests/ui/zero_repeat_side_effects_unfixable.stderr

@@ -0,0 +1,20 @@
+error: expression with side effects as the initial value in a zero-sized array initializer
+  --> tests/ui/zero_repeat_side_effects_unfixable.rs:7:5
+   |
+LL |     let _data = [|| 3i32; 0];
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider performing the side effect separately
+   = note: `-D clippy::zero-repeat-side-effects` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::zero_repeat_side_effects)]`
+
+error: expression with side effects as the initial value in a zero-sized array initializer
+  --> tests/ui/zero_repeat_side_effects_unfixable.rs:11:5
+   |
+LL |     let _data = [panic!(); 0];
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider performing the side effect separately
+
+error: aborting due to 2 previous errors
+