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Switch from macro_expansion to early pass
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@GuillaumeGomez
GuillaumeGomez committed Apr 18, 2021
1 parent 47fdfc8 commit 6c8e925
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Showing 5 changed files with 152 additions and 134 deletions.
120 changes: 34 additions & 86 deletions clippy_lints/src/bool_assert_comparison.rs
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Original file line number Diff line number Diff line change
@@ -1,12 +1,9 @@
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet;
use rustc_ast::ast::{MacArgs, MacCall};
use rustc_ast::token::{Token, TokenKind};
use rustc_ast::tokenstream::TokenTree;
use clippy_utils::{ast_utils, is_direct_expn_of};
use rustc_ast::ast::{Expr, ExprKind, Lit, LitKind};
use rustc_errors::Applicability;
use rustc_lint::{EarlyContext, EarlyLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::symbol::kw::{False, True};

declare_clippy_lint! {
/// **What it does:** This lint warns about boolean comparisons in assert-like macros.
Expand All @@ -26,102 +23,53 @@ declare_clippy_lint! {
/// assert!(!"a".is_empty());
/// ```
pub BOOL_ASSERT_COMPARISON,
pedantic,
"Using a boolean as comparison value when there is no need"
style,
"Using a boolean as comparison value in an assert_* macro when there is no need"
}

declare_lint_pass!(BoolAssertComparison => [BOOL_ASSERT_COMPARISON]);

fn is_bool(tt: Option<&TokenTree>) -> bool {
match tt {
Some(TokenTree::Token(Token {
kind: TokenKind::Ident(i, _),
fn is_bool_lit(e: &Expr) -> bool {
matches!(
e.kind,
ExprKind::Lit(Lit {
kind: LitKind::Bool(_),
..
})) => *i == True || *i == False,
_ => false,
}
})
)
}

impl EarlyLintPass for BoolAssertComparison {
fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &MacCall) {
fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &Expr) {
let macros = ["assert_eq", "debug_assert_eq"];
let inverted_macros = ["assert_ne", "debug_assert_ne"];

if let MacArgs::Delimited(_, _, ts) = &*mac.args {
let name;
if let [seg] = &*mac.path.segments {
name = seg.ident.name.as_str().to_string();
if !macros.contains(&name.as_str()) && !inverted_macros.contains(&name.as_str()) {
return;
}
} else {
return;
}
let mut has_true = false;
let mut has_false = false;
let mut bool_span = None;
let mut spans = Vec::new();
let mut nb_comma = 0;
let mut iter = ts.trees().peekable();
while let Some(tt) = iter.next() {
if let TokenTree::Token(ref token) = tt {
match token.kind {
TokenKind::Ident(i, _) => {
// We only want to check the comparison arguments, nothing else!
if nb_comma < 2 {
if i == True {
has_true = true;
bool_span = Some(token.span);
continue;
} else if i == False {
has_false = true;
bool_span = Some(token.span);
continue;
}
}
},
TokenKind::Comma => {
nb_comma += 1;
if nb_comma > 1 || !is_bool(iter.peek()) {
spans.push((token.span, true));
}
continue;
},
_ => {},
for mac in macros.iter().chain(inverted_macros.iter()) {
if let Some(span) = is_direct_expn_of(e.span, mac) {
if let Some([a, b]) = ast_utils::extract_assert_macro_args(e) {
let nb_bool_args = is_bool_lit(a) as usize + is_bool_lit(b) as usize;

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;
}

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,
);
}
spans.push((tt.span(), false));
}
#[allow(clippy::if_same_then_else)] // It allows better code reability here.
if has_false && has_true {
// Don't know what's going on here, but better leave things as is...
return;
} else if !has_true && !has_false {
// No problem detected!
return;
}
let text = spans
.into_iter()
.map(|(s, needs_whitespace)| {
let mut s = snippet(cx, s, "arg").to_string();
if needs_whitespace {
s.push(' ');
}
s
})
.collect::<String>();
let is_cond_inverted = inverted_macros.contains(&name.as_str());
let extra = (has_true && is_cond_inverted) || has_false;

span_lint_and_sugg(
cx,
BOOL_ASSERT_COMPARISON,
bool_span.expect("failed to get the bool span"),
"assert macro with a boolean comparison",
"replace it with",
format!("{}!({}{})", &name[..name.len() - 3], if extra { "!" } else { "" }, text),
Applicability::MachineApplicable,
);
}
}
}
5 changes: 3 additions & 2 deletions clippy_lints/src/lib.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -394,7 +394,6 @@ pub fn register_pre_expansion_lints(store: &mut rustc_lint::LintStore) {
store.register_pre_expansion_pass(|| box write::Write::default());
store.register_pre_expansion_pass(|| box attrs::EarlyAttributes);
store.register_pre_expansion_pass(|| box dbg_macro::DbgMacro);
store.register_pre_expansion_pass(|| box bool_assert_comparison::BoolAssertComparison);
}

#[doc(hidden)]
Expand Down Expand Up @@ -1273,6 +1272,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| box from_str_radix_10::FromStrRadix10);
store.register_late_pass(|| box manual_map::ManualMap);
store.register_late_pass(move || box if_then_some_else_none::IfThenSomeElseNone::new(msrv));
store.register_early_pass(|| box bool_assert_comparison::BoolAssertComparison);

store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![
LintId::of(arithmetic::FLOAT_ARITHMETIC),
Expand Down Expand Up @@ -1335,7 +1335,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(await_holding_invalid::AWAIT_HOLDING_LOCK),
LintId::of(await_holding_invalid::AWAIT_HOLDING_REFCELL_REF),
LintId::of(bit_mask::VERBOSE_BIT_MASK),
LintId::of(bool_assert_comparison::BOOL_ASSERT_COMPARISON),
LintId::of(bytecount::NAIVE_BYTECOUNT),
LintId::of(case_sensitive_file_extension_comparisons::CASE_SENSITIVE_FILE_EXTENSION_COMPARISONS),
LintId::of(casts::CAST_LOSSLESS),
Expand Down Expand Up @@ -1452,6 +1451,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(bit_mask::INEFFECTIVE_BIT_MASK),
LintId::of(blacklisted_name::BLACKLISTED_NAME),
LintId::of(blocks_in_if_conditions::BLOCKS_IN_IF_CONDITIONS),
LintId::of(bool_assert_comparison::BOOL_ASSERT_COMPARISON),
LintId::of(booleans::LOGIC_BUG),
LintId::of(booleans::NONMINIMAL_BOOL),
LintId::of(casts::CAST_REF_TO_MUT),
Expand Down Expand Up @@ -1738,6 +1738,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(attrs::BLANKET_CLIPPY_RESTRICTION_LINTS),
LintId::of(blacklisted_name::BLACKLISTED_NAME),
LintId::of(blocks_in_if_conditions::BLOCKS_IN_IF_CONDITIONS),
LintId::of(bool_assert_comparison::BOOL_ASSERT_COMPARISON),
LintId::of(casts::FN_TO_NUMERIC_CAST),
LintId::of(casts::FN_TO_NUMERIC_CAST_WITH_TRUNCATION),
LintId::of(collapsible_if::COLLAPSIBLE_ELSE_IF),
Expand Down
30 changes: 30 additions & 0 deletions clippy_utils/src/ast_utils.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
#![allow(clippy::similar_names, clippy::wildcard_imports, clippy::enum_glob_use)]

use crate::{both, over};
use if_chain::if_chain;
use rustc_ast::ptr::P;
use rustc_ast::{self as ast, *};
use rustc_span::symbol::Ident;
Expand Down Expand Up @@ -571,3 +572,32 @@ pub fn eq_mac_args(l: &MacArgs, r: &MacArgs) -> bool {
_ => false,
}
}

/// Extract args from an assert-like macro.
/// Currently working with:
/// - `assert!`, `assert_eq!` and `assert_ne!`
/// - `debug_assert!`, `debug_assert_eq!` and `debug_assert_ne!`
/// For example:
/// `assert!(expr)` will return Some([expr])
/// `debug_assert_eq!(a, b)` will return Some([a, b])
pub fn extract_assert_macro_args(mut expr: &Expr) -> Option<[&Expr; 2]> {
if_chain! {
if let ExprKind::If(_, ref block, _) = expr.kind;
if let StmtKind::Semi(ref e) = block.stmts.get(0)?.kind;
then {
expr = e;
}
}
if_chain! {
if let ExprKind::Block(ref block, _) = expr.kind;
if let StmtKind::Expr(ref expr) = block.stmts.get(0)?.kind;
if let ExprKind::Match(ref match_expr, _) = expr.kind;
if let ExprKind::Tup(ref tup) = match_expr.kind;
if let [a, b, ..] = tup.as_slice();
if let (&ExprKind::AddrOf(_, _, ref a), &ExprKind::AddrOf(_, _, ref b)) = (&a.kind, &b.kind);
then {
return Some([&*a, &*b]);
}
}
None
}
21 changes: 21 additions & 0 deletions tests/ui/bool_assert_comparison.rs
View file
Original file line number Diff line number Diff line change
@@ -1,30 +1,51 @@
#![warn(clippy::bool_assert_comparison)]

macro_rules! a {
() => {
true
};
}
macro_rules! b {
() => {
true
};
}

fn main() {
assert_eq!("a".len(), 1);
assert_eq!("a".is_empty(), false);
assert_eq!("".is_empty(), true);
assert_eq!(true, "".is_empty());
assert_eq!(a!(), b!());

assert_ne!("a".len(), 1);
assert_ne!("a".is_empty(), false);
assert_ne!("".is_empty(), true);
assert_ne!(true, "".is_empty());
assert_ne!(a!(), b!());

debug_assert_eq!("a".len(), 1);
debug_assert_eq!("a".is_empty(), false);
debug_assert_eq!("".is_empty(), true);
debug_assert_eq!(true, "".is_empty());
debug_assert_eq!(a!(), b!());

debug_assert_ne!("a".len(), 1);
debug_assert_ne!("a".is_empty(), false);
debug_assert_ne!("".is_empty(), true);
debug_assert_ne!(true, "".is_empty());
debug_assert_ne!(a!(), b!());

// assert with error messages
assert_eq!("a".len(), 1, "tadam {}", 1);
assert_eq!("a".len(), 1, "tadam {}", true);
assert_eq!("a".is_empty(), false, "tadam {}", 1);
assert_eq!("a".is_empty(), false, "tadam {}", true);
assert_eq!(false, "a".is_empty(), "tadam {}", true);

debug_assert_eq!("a".len(), 1, "tadam {}", 1);
debug_assert_eq!("a".len(), 1, "tadam {}", true);
debug_assert_eq!("a".is_empty(), false, "tadam {}", 1);
debug_assert_eq!("a".is_empty(), false, "tadam {}", true);
debug_assert_eq!(false, "a".is_empty(), "tadam {}", true);
}
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