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Reduce duplication

This commit is contained in:
Matthias Seiffert 2019-10-07 22:08:00 +02:00
parent 22f057972f
commit 6ee8d751f6
1 changed files with 59 additions and 64 deletions
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123
clippy_lints/src/assertions_on_constants.rs
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@ -1,12 +1,11 @@
use crate::consts::{constant, Constant};
use crate::utils::paths;
use crate::utils::{is_direct_expn_of, is_expn_of, match_def_path, span_help_and_lint, snippet};
use crate::utils::{is_direct_expn_of, is_expn_of, match_def_path, snippet_opt, span_help_and_lint};
use if_chain::if_chain;
use rustc::hir::*;
use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
use rustc::{declare_lint_pass, declare_tool_lint};
use syntax::ast::LitKind;
use std::borrow::Cow;
declare_clippy_lint! {
/// **What it does:** Checks for `assert!(true)` and `assert!(false)` calls.
@ -34,72 +33,68 @@ declare_lint_pass!(AssertionsOnConstants => [ASSERTIONS_ON_CONSTANTS]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssertionsOnConstants {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
let lint_assert_cb = |is_debug_assert: bool| {
if let ExprKind::Unary(_, ref lit) = e.kind {
if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.tables, lit) {
if is_true {
span_help_and_lint(
cx,
ASSERTIONS_ON_CONSTANTS,
e.span,
"`assert!(true)` will be optimized out by the compiler",
"remove it",
);
} else if !is_debug_assert {
span_help_and_lint(
cx,
ASSERTIONS_ON_CONSTANTS,
e.span,
"`assert!(false)` should probably be replaced",
"use `panic!()` or `unreachable!()`",
);
}
}
}
let lint_true = || {
span_help_and_lint(
cx,
ASSERTIONS_ON_CONSTANTS,
e.span,
"`assert!(true)` will be optimized out by the compiler",
"remove it",
);
};
let lint_false_without_message = || {
span_help_and_lint(
cx,
ASSERTIONS_ON_CONSTANTS,
e.span,
"`assert!(false)` should probably be replaced",
"use `panic!()` or `unreachable!()`",
);
};
let lint_false_with_message = |panic_message: String| {
span_help_and_lint(
cx,
ASSERTIONS_ON_CONSTANTS,
e.span,
&format!("`assert!(false, {})` should probably be replaced", panic_message),
&format!("use `panic!({})` or `unreachable!({})`", panic_message, panic_message),
)
};
if let Some(debug_assert_span) = is_expn_of(e.span, "debug_assert") {
if debug_assert_span.from_expansion() {
return;
}
lint_assert_cb(true);
if_chain! {
if let ExprKind::Unary(_, ref lit) = e.kind;
if let Some((Constant::Bool(is_true), _)) = constant(cx, cx.tables, lit);
if is_true;
then {
lint_true();
}
};
} else if let Some(assert_span) = is_direct_expn_of(e.span, "assert") {
if assert_span.from_expansion() {
return;
}
if let Some((panic_message, is_true)) = assert_with_message(&cx, e) {
if is_true {
span_help_and_lint(
cx,
ASSERTIONS_ON_CONSTANTS,
e.span,
"`assert!(true)` will be optimized out by the compiler",
"remove it",
);
} else if panic_message.is_empty() || panic_message.starts_with("\"assertion failed: ") {
span_help_and_lint(
cx,
ASSERTIONS_ON_CONSTANTS,
e.span,
"`assert!(false)` should probably be replaced",
"use `panic!()` or `unreachable!()`",
);
} else {
span_help_and_lint(
cx,
ASSERTIONS_ON_CONSTANTS,
e.span,
&format!("`assert!(false, {})` should probably be replaced", panic_message,),
&format!(
"use `panic!({})` or `unreachable!({})`",
panic_message, panic_message,
),
);
}
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(),
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
@ -113,13 +108,8 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssertionsOnConstants {
/// };
/// ```
///
/// where `message` is a string literal and `c` is a constant bool.
///
/// TODO extend this to match anything as message not just string literals
///
/// Returns the `message` argument of `begin_panic` and the value of `c` which is the
/// first argument of `assert!`.
fn assert_with_message<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> Option<(Cow<'a, str>, bool)> {
/// where `message` is any expression and `c` is a constant bool.
fn match_assert_with_message<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> Option<AssertKind> {
if_chain! {
if let ExprKind::Match(ref expr, ref arms, _) = expr.kind;
// matches { let _t = expr; _t }
@ -140,12 +130,17 @@ fn assert_with_message<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -
// function call
if let Some(args) = match_function_call(cx, begin_panic_call, &paths::BEGIN_PANIC);
if args.len() == 2;
// bind the second argument of the `assert!` macro
let panic_message_arg = snippet(cx, args[0].span, "..");
// bind the second argument of the `assert!` macro if it exists
if let panic_message = snippet_opt(cx, args[0].span);
// second argument of begin_panic is irrelevant
// as is the second match arm
then {
return Some((panic_message_arg, is_true));
// 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