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LythenasLythenas
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Reduce duplication
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-64
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+59
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‎clippy_lints/src/assertions_on_constants.rs‎

Lines changed: 59 additions & 64 deletions
Original file line numberDiff line numberDiff line change
@@ -1,12 +1,11 @@
11
use crate::consts::{constant, Constant};
22
use crate::utils::paths;
3-
use crate::utils::{is_direct_expn_of, is_expn_of, match_def_path, span_help_and_lint, snippet};
3+
use crate::utils::{is_direct_expn_of, is_expn_of, match_def_path, snippet_opt, span_help_and_lint};
44
use if_chain::if_chain;
55
use rustc::hir::*;
66
use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
77
use rustc::{declare_lint_pass, declare_tool_lint};
88
use syntax::ast::LitKind;
9-
use std::borrow::Cow;
109

1110
declare_clippy_lint! {
1211
/// **What it does:** Checks for `assert!(true)` and `assert!(false)` calls.
@@ -34,72 +33,68 @@ declare_lint_pass!(AssertionsOnConstants => [ASSERTIONS_ON_CONSTANTS]);
3433

3534
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssertionsOnConstants {
3635
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
37-
let lint_assert_cb = |is_debug_assert: bool| {
38-
if let ExprKind::Unary(_, ref lit) = e.kind {
39-
if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.tables, lit) {
40-
if is_true {
41-
span_help_and_lint(
42-
cx,
43-
ASSERTIONS_ON_CONSTANTS,
44-
e.span,
45-
"`assert!(true)` will be optimized out by the compiler",
46-
"remove it",
47-
);
48-
} else if !is_debug_assert {
49-
span_help_and_lint(
50-
cx,
51-
ASSERTIONS_ON_CONSTANTS,
52-
e.span,
53-
"`assert!(false)` should probably be replaced",
54-
"use `panic!()` or `unreachable!()`",
55-
);
56-
}
57-
}
58-
}
36+
let lint_true = || {
37+
span_help_and_lint(
38+
cx,
39+
ASSERTIONS_ON_CONSTANTS,
40+
e.span,
41+
"`assert!(true)` will be optimized out by the compiler",
42+
"remove it",
43+
);
44+
};
45+
let lint_false_without_message = || {
46+
span_help_and_lint(
47+
cx,
48+
ASSERTIONS_ON_CONSTANTS,
49+
e.span,
50+
"`assert!(false)` should probably be replaced",
51+
"use `panic!()` or `unreachable!()`",
52+
);
5953
};
54+
let lint_false_with_message = |panic_message: String| {
55+
span_help_and_lint(
56+
cx,
57+
ASSERTIONS_ON_CONSTANTS,
58+
e.span,
59+
&format!("`assert!(false, {})` should probably be replaced", panic_message),
60+
&format!("use `panic!({})` or `unreachable!({})`", panic_message, panic_message),
61+
)
62+
};
63+
6064
if let Some(debug_assert_span) = is_expn_of(e.span, "debug_assert") {
6165
if debug_assert_span.from_expansion() {
6266
return;
6367
}
64-
lint_assert_cb(true);
68+
if_chain! {
69+
if let ExprKind::Unary(_, ref lit) = e.kind;
70+
if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.tables, lit);
71+
if is_true;
72+
then {
73+
lint_true();
74+
}
75+
};
6576
} else if let Some(assert_span) = is_direct_expn_of(e.span, "assert") {
6677
if assert_span.from_expansion() {
6778
return;
6879
}
69-
if let Some((panic_message, is_true)) = assert_with_message(&cx, e) {
70-
if is_true {
71-
span_help_and_lint(
72-
cx,
73-
ASSERTIONS_ON_CONSTANTS,
74-
e.span,
75-
"`assert!(true)` will be optimized out by the compiler",
76-
"remove it",
77-
);
78-
} else if panic_message.is_empty() || panic_message.starts_with("\"assertion failed: ") {
79-
span_help_and_lint(
80-
cx,
81-
ASSERTIONS_ON_CONSTANTS,
82-
e.span,
83-
"`assert!(false)` should probably be replaced",
84-
"use `panic!()` or `unreachable!()`",
85-
);
86-
} else {
87-
span_help_and_lint(
88-
cx,
89-
ASSERTIONS_ON_CONSTANTS,
90-
e.span,
91-
&format!("`assert!(false, {})` should probably be replaced", panic_message,),
92-
&format!(
93-
"use `panic!({})` or `unreachable!({})`",
94-
panic_message, panic_message,
95-
),
96-
);
97-
}
80+
if let Some(assert_match) = match_assert_with_message(&cx, e) {
81+
match assert_match {
82+
// matched assert but not message
83+
AssertKind::WithoutMessage(false) => lint_false_without_message(),
84+
AssertKind::WithoutMessage(true) | AssertKind::WithMessage(_, true) => lint_true(),
85+
AssertKind::WithMessage(panic_message, false) => lint_false_with_message(panic_message),
86+
};
9887
}
9988
}
10089
}
10190
}
10291

92+
/// Result of calling `match_assert_with_message`.
93+
enum AssertKind {
94+
WithMessage(String, bool),
95+
WithoutMessage(bool),
96+
}
97+
10398
/// Check if the expression matches
10499
///
105100
/// ```rust,ignore
@@ -113,13 +108,8 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssertionsOnConstants {
113108
/// };
114109
/// ```
115110
///
116-
/// where `message` is a string literal and `c` is a constant bool.
117-
///
118-
/// TODO extend this to match anything as message not just string literals
119-
///
120-
/// Returns the `message` argument of `begin_panic` and the value of `c` which is the
121-
/// first argument of `assert!`.
122-
fn assert_with_message<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> Option<(Cow<'a, str>, bool)> {
111+
/// where `message` is any expression and `c` is a constant bool.
112+
fn match_assert_with_message<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> Option<AssertKind> {
123113
if_chain! {
124114
if let ExprKind::Match(ref expr, ref arms, _) = expr.kind;
125115
// matches { let _t = expr; _t }
@@ -140,12 +130,17 @@ fn assert_with_message<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -
140130
// function call
141131
if let Some(args) = match_function_call(cx, begin_panic_call, &paths::BEGIN_PANIC);
142132
if args.len() == 2;
143-
// bind the second argument of the `assert!` macro
144-
let panic_message_arg = snippet(cx, args[0].span, "..");
133+
// bind the second argument of the `assert!` macro if it exists
134+
if let panic_message = snippet_opt(cx, args[0].span);
145135
// second argument of begin_panic is irrelevant
146136
// as is the second match arm
147137
then {
148-
return Some((panic_message_arg, is_true));
138+
// an empty message occurs when it was generated by the macro
139+
// (and not passed by the user)
140+
return panic_message
141+
.filter(|msg| !msg.is_empty())
142+
.map(|msg| AssertKind::WithMessage(msg, is_true))
143+
.or(Some(AssertKind::WithoutMessage(is_true)));
149144
}
150145
}
151146
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