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Address some of the code style issues
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@ -1,7 +1,6 @@
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use clippy_utils::consts::{constant, Constant};
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use clippy_utils::diagnostics::span_lint_and_help;
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use clippy_utils::{is_integer_literal, is_path_diagnostic_item};
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use if_chain::if_chain;
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use rustc_hir::{BinOpKind, Expr, ExprKind, TyKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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@ -33,19 +32,24 @@ declare_clippy_lint! {
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}
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declare_lint_pass!(FnNullCheck => [FN_NULL_CHECK]);
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const LINT_MSG: &str = "function pointer assumed to be nullable, even though it isn't";
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const HELP_MSG: &str = "try wrapping your function pointer type in `Option<T>` instead, and using `is_none` to check for null pointer value";
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fn lint_expr(cx: &LateContext<'_>, expr: &Expr<'_>) {
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span_lint_and_help(
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cx,
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FN_NULL_CHECK,
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expr.span,
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"function pointer assumed to be nullable, even though it isn't",
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None,
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"try wrapping your function pointer type in `Option<T>` instead, and using `is_none` to check for null pointer value",
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)
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}
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fn is_fn_ptr_cast(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
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if_chain! {
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if let ExprKind::Cast(cast_expr, cast_ty) = expr.kind;
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if let TyKind::Ptr(_) = cast_ty.kind;
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if cx.typeck_results().expr_ty_adjusted(cast_expr).is_fn();
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then {
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true
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} else {
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false
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}
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if let ExprKind::Cast(cast_expr, cast_ty) = expr.kind
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&& let TyKind::Ptr(_) = cast_ty.kind
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{
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cx.typeck_results().expr_ty_adjusted(cast_expr).is_fn()
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} else {
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false
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}
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}
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@ -53,20 +57,12 @@ impl<'tcx> LateLintPass<'tcx> for FnNullCheck {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
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// Catching:
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// (fn_ptr as *<const/mut> <ty>).is_null()
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if_chain! {
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if let ExprKind::MethodCall(method_name, receiver, _, _) = expr.kind;
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if method_name.ident.as_str() == "is_null";
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if is_fn_ptr_cast(cx, receiver);
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then {
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span_lint_and_help(
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cx,
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FN_NULL_CHECK,
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expr.span,
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LINT_MSG,
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None,
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HELP_MSG
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);
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}
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if let ExprKind::MethodCall(method_name, receiver, _, _) = expr.kind
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&& method_name.ident.as_str() == "is_null"
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&& is_fn_ptr_cast(cx, receiver)
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{
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lint_expr(cx, expr);
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return;
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}
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if let ExprKind::Binary(op, left, right) = expr.kind
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@ -85,28 +81,14 @@ impl<'tcx> LateLintPass<'tcx> for FnNullCheck {
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// (fn_ptr as *<const/mut> <ty>) == <const that evaluates to null_ptr>
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let c = constant(cx, cx.typeck_results(), to_check);
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if let Some((Constant::RawPtr(0), _)) = c {
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span_lint_and_help(
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cx,
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FN_NULL_CHECK,
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expr.span,
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LINT_MSG,
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None,
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HELP_MSG
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);
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lint_expr(cx, expr);
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return;
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}
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// Catching:
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// (fn_ptr as *<const/mut> <ty>) == (0 as <ty>)
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if let ExprKind::Cast(cast_expr, _) = to_check.kind && is_integer_literal(cast_expr, 0) {
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span_lint_and_help(
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cx,
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FN_NULL_CHECK,
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expr.span,
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LINT_MSG,
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None,
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HELP_MSG
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);
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lint_expr(cx, expr);
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return;
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}
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@ -115,14 +97,7 @@ impl<'tcx> LateLintPass<'tcx> for FnNullCheck {
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if let ExprKind::Call(func, []) = to_check.kind &&
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is_path_diagnostic_item(cx, func, sym::ptr_null)
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{
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span_lint_and_help(
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cx,
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FN_NULL_CHECK,
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expr.span,
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LINT_MSG,
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None,
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HELP_MSG
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);
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lint_expr(cx, expr);
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}
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}
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}
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@ -18,7 +18,8 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, arg: &'t
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return false;
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}
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// Catching transmute over constants that resolve to `null`.
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// Catching:
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// transmute over constants that resolve to `null`.
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let mut const_eval_context = constant_context(cx, cx.typeck_results());
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if let ExprKind::Path(ref _qpath) = arg.kind &&
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let Some(Constant::RawPtr(0)) = const_eval_context.expr(arg)
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