//! calculate cognitive complexity and warn about overly complex functions
-use rustc::hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
-use rustc::hir::*;
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintContext, LintPass};
-use rustc::{declare_tool_lint, impl_lint_pass};
-use syntax::ast::Attribute;
-use syntax::source_map::Span;
+use rustc_ast::ast::Attribute;
+use rustc_hir::intravisit::{walk_expr, FnKind, NestedVisitorMap, Visitor};
+use rustc_hir::{Body, Expr, ExprKind, FnDecl, HirId};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_middle::hir::map::Map;
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::source_map::Span;
+use rustc_span::{sym, BytePos};
-use crate::utils::{match_type, paths, span_help_and_lint, LimitStack};
+use crate::utils::{is_type_diagnostic_item, snippet_opt, span_lint_and_help, LimitStack};
declare_clippy_lint! {
/// **What it does:** Checks for methods with high cognitive complexity.
///
/// **Example:** No. You'll see it when you get the warning.
pub COGNITIVE_COMPLEXITY,
- complexity,
+ nursery,
"functions that should be split up into multiple functions"
}
}
impl CognitiveComplexity {
+ #[must_use]
pub fn new(limit: u64) -> Self {
Self {
limit: LimitStack::new(limit),
impl_lint_pass!(CognitiveComplexity => [COGNITIVE_COMPLEXITY]);
impl CognitiveComplexity {
- fn check<'a, 'tcx>(&mut self, cx: &'a LateContext<'a, 'tcx>, body: &'tcx Body, span: Span) {
- if span.from_expansion() {
+ #[allow(clippy::cast_possible_truncation)]
+ fn check<'tcx>(
+ &mut self,
+ cx: &LateContext<'tcx>,
+ kind: FnKind<'tcx>,
+ decl: &'tcx FnDecl<'_>,
+ body: &'tcx Body<'_>,
+ body_span: Span,
+ ) {
+ if body_span.from_expansion() {
return;
}
let mut helper = CCHelper { cc: 1, returns: 0 };
helper.visit_expr(expr);
let CCHelper { cc, returns } = helper;
- let ret_ty = cx.tables.node_type(expr.hir_id);
- let ret_adjust = if match_type(cx, ret_ty, &paths::RESULT) {
+ let ret_ty = cx.typeck_results().node_type(expr.hir_id);
+ let ret_adjust = if is_type_diagnostic_item(cx, ret_ty, sym::result_type) {
returns
} else {
#[allow(clippy::integer_division)]
if rust_cc >= ret_adjust {
rust_cc -= ret_adjust;
}
+
if rust_cc > self.limit.limit() {
- span_help_and_lint(
+ let fn_span = match kind {
+ FnKind::ItemFn(ident, _, _, _, _) | FnKind::Method(ident, _, _, _) => ident.span,
+ FnKind::Closure(_) => {
+ let header_span = body_span.with_hi(decl.output.span().lo());
+ let pos = snippet_opt(cx, header_span).and_then(|snip| {
+ let low_offset = snip.find('|')?;
+ let high_offset = 1 + snip.get(low_offset + 1..)?.find('|')?;
+ let low = header_span.lo() + BytePos(low_offset as u32);
+ let high = low + BytePos(high_offset as u32 + 1);
+
+ Some((low, high))
+ });
+
+ if let Some((low, high)) = pos {
+ Span::new(low, high, header_span.ctxt())
+ } else {
+ return;
+ }
+ },
+ };
+
+ span_lint_and_help(
cx,
COGNITIVE_COMPLEXITY,
- span,
+ fn_span,
&format!(
"the function has a cognitive complexity of ({}/{})",
rust_cc,
self.limit.limit()
),
+ None,
"you could split it up into multiple smaller functions",
);
}
}
}
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for CognitiveComplexity {
+impl<'tcx> LateLintPass<'tcx> for CognitiveComplexity {
fn check_fn(
&mut self,
- cx: &LateContext<'a, 'tcx>,
- _: intravisit::FnKind<'tcx>,
- _: &'tcx FnDecl,
- body: &'tcx Body,
+ cx: &LateContext<'tcx>,
+ kind: FnKind<'tcx>,
+ decl: &'tcx FnDecl<'_>,
+ body: &'tcx Body<'_>,
span: Span,
hir_id: HirId,
) {
let def_id = cx.tcx.hir().local_def_id(hir_id);
- if !cx.tcx.has_attr(def_id, sym!(test)) {
- self.check(cx, body, span);
+ if !cx.tcx.has_attr(def_id.to_def_id(), sym::test) {
+ self.check(cx, kind, decl, body, span);
}
}
- fn enter_lint_attrs(&mut self, cx: &LateContext<'a, 'tcx>, attrs: &'tcx [Attribute]) {
+ fn enter_lint_attrs(&mut self, cx: &LateContext<'tcx>, attrs: &'tcx [Attribute]) {
self.limit.push_attrs(cx.sess(), attrs, "cognitive_complexity");
}
- fn exit_lint_attrs(&mut self, cx: &LateContext<'a, 'tcx>, attrs: &'tcx [Attribute]) {
+ fn exit_lint_attrs(&mut self, cx: &LateContext<'tcx>, attrs: &'tcx [Attribute]) {
self.limit.pop_attrs(cx.sess(), attrs, "cognitive_complexity");
}
}
}
impl<'tcx> Visitor<'tcx> for CCHelper {
- fn visit_expr(&mut self, e: &'tcx Expr) {
+ type Map = Map<'tcx>;
+
+ fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
walk_expr(self, e);
- match e.node {
+ match e.kind {
ExprKind::Match(_, ref arms, _) => {
if arms.len() > 1 {
self.cc += 1;
_ => {},
}
}
- fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
+ fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
}