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use clippy_utils ::diagnostics ::span_lint_and_then ;
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use clippy_utils ::macros ::root_macro_call_first_node ;
use clippy_utils ::return_ty ;
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use clippy_utils ::ty ::is_type_diagnostic_item ;
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use clippy_utils ::visitors ::expr_visitor_no_bodies ;
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use rustc_hir as hir ;
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use rustc_hir ::intravisit ::{ FnKind , Visitor } ;
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use rustc_lint ::{ LateContext , LateLintPass } ;
use rustc_session ::{ declare_lint_pass , declare_tool_lint } ;
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use rustc_span ::{ sym , Span } ;
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declare_clippy_lint! {
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/// ### What it does
/// Checks for usage of `panic!`, `unimplemented!`, `todo!`, `unreachable!` or assertions in a function of type result.
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///
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/// ### Why is this bad?
/// For some codebases, it is desirable for functions of type result to return an error instead of crashing. Hence panicking macros should be avoided.
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///
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/// ### Known problems
/// Functions called from a function returning a `Result` may invoke a panicking macro. This is not checked.
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///
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/// ### Example
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/// ```rust
/// fn result_with_panic() -> Result<bool, String>
/// {
/// panic!("error");
/// }
/// ```
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/// Use instead:
/// ```rust
/// fn result_without_panic() -> Result<bool, String> {
/// Err(String::from("error"))
/// }
/// ```
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#[ clippy::version = " 1.48.0 " ]
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pub PANIC_IN_RESULT_FN ,
restriction ,
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" functions of type `Result<..>` that contain `panic!()`, `todo!()`, `unreachable()`, `unimplemented()` or assertion "
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}
declare_lint_pass! ( PanicInResultFn = > [ PANIC_IN_RESULT_FN ] ) ;
impl < ' tcx > LateLintPass < ' tcx > for PanicInResultFn {
fn check_fn (
& mut self ,
cx : & LateContext < ' tcx > ,
fn_kind : FnKind < ' tcx > ,
_ : & ' tcx hir ::FnDecl < ' tcx > ,
body : & ' tcx hir ::Body < ' tcx > ,
span : Span ,
hir_id : hir ::HirId ,
) {
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if ! matches! ( fn_kind , FnKind ::Closure ) & & is_type_diagnostic_item ( cx , return_ty ( cx , hir_id ) , sym ::Result ) {
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lint_impl_body ( cx , span , body ) ;
}
}
}
fn lint_impl_body < ' tcx > ( cx : & LateContext < ' tcx > , impl_span : Span , body : & ' tcx hir ::Body < ' tcx > ) {
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let mut panics = Vec ::new ( ) ;
expr_visitor_no_bodies ( | expr | {
let Some ( macro_call ) = root_macro_call_first_node ( cx , expr ) else { return true } ;
if matches! (
& * cx . tcx . item_name ( macro_call . def_id ) . as_str ( ) ,
" unimplemented " | " unreachable " | " panic " | " todo " | " assert " | " assert_eq " | " assert_ne "
) {
panics . push ( macro_call . span ) ;
return false ;
}
true
} )
. visit_expr ( & body . value ) ;
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if ! panics . is_empty ( ) {
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span_lint_and_then (
cx ,
PANIC_IN_RESULT_FN ,
impl_span ,
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" used `unimplemented!()`, `unreachable!()`, `todo!()`, `panic!()` or assertion in a function that returns `Result` " ,
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move | diag | {
diag . help (
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" `unimplemented!()`, `unreachable!()`, `todo!()`, `panic!()` or assertions should not be used in a function that returns `Result` as `Result` is expected to return an error instead of crashing " ,
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) ;
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diag . span_note ( panics , " return Err() instead of panicking " ) ;
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} ,
) ;
}
}