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New macro utils
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Sorry, this is a big one. A lot of interrelated changes and I wanted to put the new utils to use to make sure they are somewhat battle-tested. We may want to divide some of the lint-specific refactoring commits into batches for smaller reviewing tasks. I could also split into more PRs.

Introduces a bunch of new utils at `clippy_utils::macros::...`. Please read through the docs and give any feedback! I'm happy to introduce `MacroCall` and various functions to retrieve an instance. It feels like the missing puzzle piece. I'm also introducing `ExpnId` from rustc as "useful for Clippy too". `@rust-lang/clippy`

Fixes rust-lang#7843 by not parsing every node of macro implementations, at least the major offenders.

I probably want to get rid of `is_expn_of` at some point.
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@bors
bors committed Jan 4, 2022
1 parent 3ea7784 commit 786f874
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Showing 31 changed files with 868 additions and 865 deletions.
120 changes: 25 additions & 95 deletions clippy_lints/src/assertions_on_constants.rs
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Original file line number Diff line number Diff line change
@@ -1,12 +1,10 @@
use clippy_utils::consts::{constant, Constant};
use clippy_utils::diagnostics::span_lint_and_help;
use clippy_utils::higher;
use clippy_utils::source::snippet_opt;
use clippy_utils::{is_direct_expn_of, is_expn_of, match_panic_call, peel_blocks};
use if_chain::if_chain;
use rustc_hir::{Expr, ExprKind, UnOp};
use clippy_utils::macros::{find_assert_args, root_macro_call_first_node, PanicExpn};
use rustc_hir::Expr;
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::sym;

declare_clippy_lint! {
/// ### What it does
Expand Down Expand Up @@ -36,107 +34,39 @@ declare_lint_pass!(AssertionsOnConstants => [ASSERTIONS_ON_CONSTANTS]);

impl<'tcx> LateLintPass<'tcx> for AssertionsOnConstants {
fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
let lint_true = |is_debug: bool| {
span_lint_and_help(
cx,
ASSERTIONS_ON_CONSTANTS,
e.span,
if is_debug {
"`debug_assert!(true)` will be optimized out by the compiler"
} else {
"`assert!(true)` will be optimized out by the compiler"
},
None,
"remove it",
);
let Some(macro_call) = root_macro_call_first_node(cx, e) else { return };
let is_debug = match cx.tcx.get_diagnostic_name(macro_call.def_id) {
Some(sym::debug_assert_macro) => true,
Some(sym::assert_macro) => false,
_ => return,
};
let lint_false_without_message = || {
let Some((condition, panic_expn)) = find_assert_args(cx, e, macro_call.expn) else { return };
let Some((Constant::Bool(val), _)) = constant(cx, cx.typeck_results(), condition) else { return };
if val {
span_lint_and_help(
cx,
ASSERTIONS_ON_CONSTANTS,
e.span,
"`assert!(false)` should probably be replaced",
macro_call.span,
&format!(
"`{}!(true)` will be optimized out by the compiler",
cx.tcx.item_name(macro_call.def_id)
),
None,
"use `panic!()` or `unreachable!()`",
"remove it",
);
};
let lint_false_with_message = |panic_message: String| {
} else if !is_debug {
let (assert_arg, panic_arg) = match panic_expn {
PanicExpn::Empty => ("", ""),
_ => (", ..", ".."),
};
span_lint_and_help(
cx,
ASSERTIONS_ON_CONSTANTS,
e.span,
&format!("`assert!(false, {})` should probably be replaced", panic_message),
macro_call.span,
&format!("`assert!(false{})` should probably be replaced", assert_arg),
None,
&format!("use `panic!({})` or `unreachable!({})`", panic_message, panic_message),
&format!("use `panic!({})` or `unreachable!({0})`", panic_arg),
);
};

if let Some(debug_assert_span) = is_expn_of(e.span, "debug_assert") {
if debug_assert_span.from_expansion() {
return;
}
if_chain! {
if let ExprKind::Unary(_, lit) = e.kind;
if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.typeck_results(), lit);
if is_true;
then {
lint_true(true);
}
};
} else if let Some(assert_span) = is_direct_expn_of(e.span, "assert") {
if assert_span.from_expansion() {
return;
}
if let Some(assert_match) = match_assert_with_message(cx, e) {
match assert_match {
// matched assert but not message
AssertKind::WithoutMessage(false) => lint_false_without_message(),
AssertKind::WithoutMessage(true) | AssertKind::WithMessage(_, true) => lint_true(false),
AssertKind::WithMessage(panic_message, false) => lint_false_with_message(panic_message),
};
}
}
}
}

/// Result of calling `match_assert_with_message`.
enum AssertKind {
WithMessage(String, bool),
WithoutMessage(bool),
}

/// Check if the expression matches
///
/// ```rust,ignore
/// if !c {
/// {
/// ::std::rt::begin_panic(message, _)
/// }
/// }
/// ```
///
/// where `message` is any expression and `c` is a constant bool.
fn match_assert_with_message<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<AssertKind> {
if_chain! {
if let Some(higher::If { cond, then, .. }) = higher::If::hir(expr);
if let ExprKind::Unary(UnOp::Not, expr) = cond.kind;
// bind the first argument of the `assert!` macro
if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.typeck_results(), expr);
let begin_panic_call = peel_blocks(then);
// function call
if let Some(arg) = match_panic_call(cx, begin_panic_call);
// bind the second argument of the `assert!` macro if it exists
if let panic_message = snippet_opt(cx, arg.span);
// second argument of begin_panic is irrelevant
// as is the second match arm
then {
// an empty message occurs when it was generated by the macro
// (and not passed by the user)
return panic_message
.filter(|msg| !msg.is_empty())
.map(|msg| AssertKind::WithMessage(msg, is_true))
.or(Some(AssertKind::WithoutMessage(is_true)));
}
}
None
}
18 changes: 7 additions & 11 deletions clippy_lints/src/attrs.rs
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Original file line number Diff line number Diff line change
@@ -1,9 +1,10 @@
//! checks for attributes

use clippy_utils::diagnostics::{span_lint, span_lint_and_help, span_lint_and_sugg, span_lint_and_then};
use clippy_utils::macros::{is_panic, macro_backtrace};
use clippy_utils::msrvs;
use clippy_utils::source::{first_line_of_span, is_present_in_source, snippet_opt, without_block_comments};
use clippy_utils::{extract_msrv_attr, match_panic_def_id, meets_msrv};
use clippy_utils::{extract_msrv_attr, meets_msrv};
use if_chain::if_chain;
use rustc_ast::{AttrKind, AttrStyle, Attribute, Lit, LitKind, MetaItemKind, NestedMetaItem};
use rustc_errors::Applicability;
Expand Down Expand Up @@ -443,20 +444,15 @@ fn is_relevant_block(cx: &LateContext<'_>, typeck_results: &ty::TypeckResults<'_
}

fn is_relevant_expr(cx: &LateContext<'_>, typeck_results: &ty::TypeckResults<'_>, expr: &Expr<'_>) -> bool {
if macro_backtrace(expr.span).last().map_or(false, |macro_call| {
is_panic(cx, macro_call.def_id) || cx.tcx.item_name(macro_call.def_id) == sym::unreachable
}) {
return false;
}
match &expr.kind {
ExprKind::Block(block, _) => is_relevant_block(cx, typeck_results, block),
ExprKind::Ret(Some(e)) => is_relevant_expr(cx, typeck_results, e),
ExprKind::Ret(None) | ExprKind::Break(_, None) => false,
ExprKind::Call(path_expr, _) => {
if let ExprKind::Path(qpath) = &path_expr.kind {
typeck_results
.qpath_res(qpath, path_expr.hir_id)
.opt_def_id()
.map_or(true, |fun_id| !match_panic_def_id(cx, fun_id))
} else {
true
}
},
_ => true,
}
}
Expand Down
73 changes: 35 additions & 38 deletions clippy_lints/src/bool_assert_comparison.rs
View file
Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
use clippy_utils::{diagnostics::span_lint_and_sugg, higher, is_direct_expn_of, ty::implements_trait};
use clippy_utils::macros::{find_assert_eq_args, root_macro_call_first_node};
use clippy_utils::{diagnostics::span_lint_and_sugg, ty::implements_trait};
use rustc_ast::ast::LitKind;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind, Lit};
Expand Down Expand Up @@ -66,44 +67,40 @@ fn is_impl_not_trait_with_bool_out(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) ->

impl<'tcx> LateLintPass<'tcx> for BoolAssertComparison {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
let macros = ["assert_eq", "debug_assert_eq"];
let inverted_macros = ["assert_ne", "debug_assert_ne"];

for mac in macros.iter().chain(inverted_macros.iter()) {
if let Some(span) = is_direct_expn_of(expr.span, mac) {
if let Some(args) = higher::extract_assert_macro_args(expr) {
if let [a, b, ..] = args[..] {
let nb_bool_args = usize::from(is_bool_lit(a)) + usize::from(is_bool_lit(b));

if nb_bool_args != 1 {
// If there are two boolean arguments, we definitely don't understand
// what's going on, so better leave things as is...
//
// Or there is simply no boolean and then we can leave things as is!
return;
}

if !is_impl_not_trait_with_bool_out(cx, a) || !is_impl_not_trait_with_bool_out(cx, b) {
// At this point the expression which is not a boolean
// literal does not implement Not trait with a bool output,
// so we cannot suggest to rewrite our code
return;
}
let Some(macro_call) = root_macro_call_first_node(cx, expr) else { return };
let macro_name = cx.tcx.item_name(macro_call.def_id);
if !matches!(
macro_name.as_str(),
"assert_eq" | "debug_assert_eq" | "assert_ne" | "debug_assert_ne"
) {
return;
}
let Some ((a, b, _)) = find_assert_eq_args(cx, expr, macro_call.expn) else { return };
if !(is_bool_lit(a) ^ is_bool_lit(b)) {
// If there are two boolean arguments, we definitely don't understand
// what's going on, so better leave things as is...
//
// Or there is simply no boolean and then we can leave things as is!
return;
}

let non_eq_mac = &mac[..mac.len() - 3];
span_lint_and_sugg(
cx,
BOOL_ASSERT_COMPARISON,
span,
&format!("used `{}!` with a literal bool", mac),
"replace it with",
format!("{}!(..)", non_eq_mac),
Applicability::MaybeIncorrect,
);
return;
}
}
}
if !is_impl_not_trait_with_bool_out(cx, a) || !is_impl_not_trait_with_bool_out(cx, b) {
// At this point the expression which is not a boolean
// literal does not implement Not trait with a bool output,
// so we cannot suggest to rewrite our code
return;
}

let macro_name = macro_name.as_str();
let non_eq_mac = &macro_name[..macro_name.len() - 3];
span_lint_and_sugg(
cx,
BOOL_ASSERT_COMPARISON,
macro_call.span,
&format!("used `{}!` with a literal bool", macro_name),
"replace it with",
format!("{}!(..)", non_eq_mac),
Applicability::MaybeIncorrect,
);
}
}
33 changes: 11 additions & 22 deletions clippy_lints/src/doc.rs
View file
Original file line number Diff line number Diff line change
@@ -1,8 +1,9 @@
use clippy_utils::attrs::is_doc_hidden;
use clippy_utils::diagnostics::{span_lint, span_lint_and_help, span_lint_and_note, span_lint_and_then};
use clippy_utils::macros::{is_panic, root_macro_call_first_node};
use clippy_utils::source::{first_line_of_span, snippet_with_applicability};
use clippy_utils::ty::{implements_trait, is_type_diagnostic_item};
use clippy_utils::{is_entrypoint_fn, is_expn_of, match_panic_def_id, method_chain_args, return_ty};
use clippy_utils::{is_entrypoint_fn, method_chain_args, return_ty};
use if_chain::if_chain;
use itertools::Itertools;
use rustc_ast::ast::{Async, AttrKind, Attribute, Fn, FnRetTy, ItemKind};
Expand All @@ -13,7 +14,7 @@ use rustc_errors::emitter::EmitterWriter;
use rustc_errors::{Applicability, Handler, SuggestionStyle};
use rustc_hir as hir;
use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
use rustc_hir::{AnonConst, Expr, ExprKind, QPath};
use rustc_hir::{AnonConst, Expr};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::hir::map::Map;
use rustc_middle::lint::in_external_macro;
Expand Down Expand Up @@ -805,24 +806,17 @@ impl<'a, 'tcx> Visitor<'tcx> for FindPanicUnwrap<'a, 'tcx> {
return;
}

// check for `begin_panic`
if_chain! {
if let ExprKind::Call(func_expr, _) = expr.kind;
if let ExprKind::Path(QPath::Resolved(_, path)) = func_expr.kind;
if let Some(path_def_id) = path.res.opt_def_id();
if match_panic_def_id(self.cx, path_def_id);
if is_expn_of(expr.span, "unreachable").is_none();
if !is_expn_of_debug_assertions(expr.span);
then {
self.panic_span = Some(expr.span);
if let Some(macro_call) = root_macro_call_first_node(self.cx, expr) {
if is_panic(self.cx, macro_call.def_id)
|| matches!(
self.cx.tcx.item_name(macro_call.def_id).as_str(),
"assert" | "assert_eq" | "assert_ne" | "todo"
)
{
self.panic_span = Some(macro_call.span);
}
}

// check for `assert_eq` or `assert_ne`
if is_expn_of(expr.span, "assert_eq").is_some() || is_expn_of(expr.span, "assert_ne").is_some() {
self.panic_span = Some(expr.span);
}

// check for `unwrap`
if let Some(arglists) = method_chain_args(expr, &["unwrap"]) {
let receiver_ty = self.typeck_results.expr_ty(&arglists[0][0]).peel_refs();
Expand All @@ -844,8 +838,3 @@ impl<'a, 'tcx> Visitor<'tcx> for FindPanicUnwrap<'a, 'tcx> {
NestedVisitorMap::OnlyBodies(self.cx.tcx.hir())
}
}

fn is_expn_of_debug_assertions(span: Span) -> bool {
const MACRO_NAMES: &[&str] = &["debug_assert", "debug_assert_eq", "debug_assert_ne"];
MACRO_NAMES.iter().any(|name| is_expn_of(span, name).is_some())
}
45 changes: 20 additions & 25 deletions clippy_lints/src/eq_op.rs
View file
Original file line number Diff line number Diff line change
@@ -1,10 +1,11 @@
use clippy_utils::diagnostics::{multispan_sugg, span_lint, span_lint_and_then};
use clippy_utils::macros::{find_assert_eq_args, first_node_macro_backtrace};
use clippy_utils::source::snippet;
use clippy_utils::ty::{implements_trait, is_copy};
use clippy_utils::{ast_utils::is_useless_with_eq_exprs, eq_expr_value, higher, is_expn_of, is_in_test_function};
use clippy_utils::{ast_utils::is_useless_with_eq_exprs, eq_expr_value, is_in_test_function};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::{BinOpKind, BorrowKind, Expr, ExprKind, StmtKind};
use rustc_hir::{BinOpKind, BorrowKind, Expr, ExprKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};

Expand Down Expand Up @@ -68,32 +69,26 @@ declare_clippy_lint! {

declare_lint_pass!(EqOp => [EQ_OP, OP_REF]);

const ASSERT_MACRO_NAMES: [&str; 4] = ["assert_eq", "assert_ne", "debug_assert_eq", "debug_assert_ne"];

impl<'tcx> LateLintPass<'tcx> for EqOp {
#[allow(clippy::similar_names, clippy::too_many_lines)]
fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
if let ExprKind::Block(block, _) = e.kind {
for stmt in block.stmts {
for amn in &ASSERT_MACRO_NAMES {
if_chain! {
if is_expn_of(stmt.span, amn).is_some();
if let StmtKind::Semi(matchexpr) = stmt.kind;
if let Some(macro_args) = higher::extract_assert_macro_args(matchexpr);
if macro_args.len() == 2;
let (lhs, rhs) = (macro_args[0], macro_args[1]);
if eq_expr_value(cx, lhs, rhs);
if !is_in_test_function(cx.tcx, e.hir_id);
then {
span_lint(
cx,
EQ_OP,
lhs.span.to(rhs.span),
&format!("identical args used in this `{}!` macro call", amn),
);
}
}
}
if_chain! {
if let Some((macro_call, macro_name)) = first_node_macro_backtrace(cx, e).find_map(|macro_call| {
let name = cx.tcx.item_name(macro_call.def_id);
matches!(name.as_str(), "assert_eq" | "assert_ne" | "debug_assert_eq" | "debug_assert_ne")
.then(|| (macro_call, name))
});
if let Some((lhs, rhs, _)) = find_assert_eq_args(cx, e, macro_call.expn);
if eq_expr_value(cx, lhs, rhs);
if macro_call.is_local();
if !is_in_test_function(cx.tcx, e.hir_id);
then {
span_lint(
cx,
EQ_OP,
lhs.span.to(rhs.span),
&format!("identical args used in this `{}!` macro call", macro_name),
);
}
}
if let ExprKind::Binary(op, left, right) = e.kind {
Expand Down
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