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use snippet_opt and span_suggestion

This commit is contained in:
Oliver Schneider 2016-03-14 17:13:10 +01:00
parent 9dc282e31d
commit 6a566a1009
2 changed files with 26 additions and 14 deletions
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20
src/needless_bool.rs
View File

@ -6,7 +6,7 @@ use rustc::lint::*;
use rustc_front::hir::*;
use syntax::ast::LitKind;
use syntax::codemap::Spanned;
use utils::{span_lint, span_lint_and_then, snippet};
use utils::{span_lint, span_lint_and_then, snippet, snippet_opt};
/// **What it does:** This lint checks for expressions of the form `if c { true } else { false }` (or vice versa) and suggest using the condition directly.
///
@ -50,16 +50,16 @@ impl LateLintPass for NeedlessBool {
use self::Expression::*;
if let ExprIf(ref pred, ref then_block, Some(ref else_expr)) = e.node {
let reduce = |hint: &str, not| {
let pred_snip = snippet(cx, pred.span, "..");
let hint = if pred_snip == ".." {
hint.into()
} else {
format!("`{}{}`", not, pred_snip)
let hint = match snippet_opt(cx, pred.span) {
Some(pred_snip) => format!("`{}{}`", not, pred_snip),
None => hint.into(),
};
span_lint(cx,
NEEDLESS_BOOL,
e.span,
&format!("you can reduce this if-then-else expression to just {}", hint));
span_lint_and_then(cx,
NEEDLESS_BOOL,
e.span,
"this if-then-else expression returns a bool literal", |db| {
db.span_suggestion(e.span, "you can reduce it to", hint);
});
};
match (fetch_bool_block(then_block), fetch_bool_expr(else_expr)) {
(RetBool(true), RetBool(true)) |

20
tests/compile-fail/needless_bool.rs
View File

@ -7,8 +7,14 @@ fn main() {
let x = true;
if x { true } else { true }; //~ERROR this if-then-else expression will always return true
if x { false } else { false }; //~ERROR this if-then-else expression will always return false
if x { true } else { false }; //~ERROR you can reduce this if-then-else expression to just `x`
if x { false } else { true }; //~ERROR you can reduce this if-then-else expression to just `!x`
if x { true } else { false };
//~^ ERROR this if-then-else expression returns a bool literal
//~| HELP you can reduce it to
//~| SUGGESTION `x`
if x { false } else { true };
//~^ ERROR this if-then-else expression returns a bool literal
//~| HELP you can reduce it to
//~| SUGGESTION `!x`
if x { x } else { false }; // would also be questionable, but we don't catch this yet
bool_ret(x);
bool_ret2(x);
@ -30,10 +36,16 @@ fn bool_ret2(x: bool) -> bool {
#[deny(needless_bool)]
fn bool_ret3(x: bool) -> bool {
if x { return true } else { return false }; //~ERROR you can reduce this if-then-else expression to just `return x`
if x { return true } else { return false };
//~^ ERROR this if-then-else expression returns a bool literal
//~| HELP you can reduce it to
//~| SUGGESTION `return x`
}
#[deny(needless_bool)]
fn bool_ret4(x: bool) -> bool {
if x { return false } else { return true }; //~ERROR you can reduce this if-then-else expression to just `return !x`
if x { return false } else { return true };
//~^ ERROR this if-then-else expression returns a bool literal
//~| HELP you can reduce it to
//~| SUGGESTION `return !x`
}