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Use `utils::sugg` in `match` related lints 

Also don't build suggestion when unnecessary.
This commit is contained in:
mcarton 2016-07-03 19:13:01 +02:00
parent cc18556ae5
commit ffa840d4f2
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GPG Key ID: 5E427C794CBA45E8
3 changed files with 70 additions and 67 deletions
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120
clippy_lints/src/matches.rs
View File

@ -235,57 +235,54 @@ fn check_single_match_opt_like(cx: &LateContext, ex: &Expr, arms: &[Arm], expr:
fn check_match_bool(cx: &LateContext, ex: &Expr, arms: &[Arm], expr: &Expr) {
// type of expression == bool
if cx.tcx.expr_ty(ex).sty == ty::TyBool {
let sugg = if arms.len() == 2 && arms[0].pats.len() == 1 {
// no guards
let exprs = if let PatKind::Lit(ref arm_bool) = arms[0].pats[0].node {
if let ExprLit(ref lit) = arm_bool.node {
match lit.node {
LitKind::Bool(true) => Some((&*arms[0].body, &*arms[1].body)),
LitKind::Bool(false) => Some((&*arms[1].body, &*arms[0].body)),
_ => None,
}
} else {
None
}
} else {
None
};
if let Some((ref true_expr, ref false_expr)) = exprs {
match (is_unit_expr(true_expr), is_unit_expr(false_expr)) {
(false, false) => {
Some(format!("if {} {} else {}",
snippet(cx, ex.span, "b"),
expr_block(cx, true_expr, None, ".."),
expr_block(cx, false_expr, None, "..")))
}
(false, true) => {
Some(format!("if {} {}", snippet(cx, ex.span, "b"), expr_block(cx, true_expr, None, "..")))
}
(true, false) => {
let test = Sugg::hir(cx, ex, "..");
Some(format!("if {} {}",
!test,
expr_block(cx, false_expr, None, "..")))
}
(true, true) => None,
}
} else {
None
}
} else {
None
};
span_lint_and_then(cx,
MATCH_BOOL,
expr.span,
"you seem to be trying to match on a boolean expression. Consider using an if..else block:",
"you seem to be trying to match on a boolean expression",
move |db| {
if let Some(sugg) = sugg {
db.span_suggestion(expr.span, "try this", sugg);
}
});
if arms.len() == 2 && arms[0].pats.len() == 1 {
// no guards
let exprs = if let PatKind::Lit(ref arm_bool) = arms[0].pats[0].node {
if let ExprLit(ref lit) = arm_bool.node {
match lit.node {
LitKind::Bool(true) => Some((&*arms[0].body, &*arms[1].body)),
LitKind::Bool(false) => Some((&*arms[1].body, &*arms[0].body)),
_ => None,
}
} else {
None
}
} else {
None
};
if let Some((ref true_expr, ref false_expr)) = exprs {
let sugg = match (is_unit_expr(true_expr), is_unit_expr(false_expr)) {
(false, false) => {
Some(format!("if {} {} else {}",
snippet(cx, ex.span, "b"),
expr_block(cx, true_expr, None, ".."),
expr_block(cx, false_expr, None, "..")))
}
(false, true) => {
Some(format!("if {} {}", snippet(cx, ex.span, "b"), expr_block(cx, true_expr, None, "..")))
}
(true, false) => {
let test = Sugg::hir(cx, ex, "..");
Some(format!("if {} {}",
!test,
expr_block(cx, false_expr, None, "..")))
}
(true, true) => None,
};
if let Some(sugg) = sugg {
db.span_suggestion(expr.span, "consider using an if/else expression", sugg);
}
}
}
});
}
}
@ -309,26 +306,28 @@ fn check_overlapping_arms(cx: &LateContext, ex: &Expr, arms: &[Arm]) {
fn check_match_ref_pats(cx: &LateContext, ex: &Expr, arms: &[Arm], source: MatchSource, expr: &Expr) {
if has_only_ref_pats(arms) {
if let ExprAddrOf(Mutability::MutImmutable, ref inner) = ex.node {
let template = match_template(cx, expr.span, source, "", inner);
span_lint_and_then(cx,
MATCH_REF_PATS,
expr.span,
"you don't need to add `&` to both the expression and the patterns",
|db| {
db.span_suggestion(expr.span, "try", template);
});
let inner = Sugg::hir(cx, inner, "..");
let template = match_template(expr.span, source, inner);
db.span_suggestion(expr.span, "try", template);
});
} else {
let template = match_template(cx, expr.span, source, "*", ex);
span_lint_and_then(cx,
MATCH_REF_PATS,
expr.span,
"you don't need to add `&` to all patterns",
|db| {
db.span_suggestion(expr.span,
"instead of prefixing all patterns with `&`, you can \
dereference the expression",
template);
});
let ex = Sugg::hir(cx, ex, "..");
let template = match_template(expr.span, source, ex.deref());
db.span_suggestion(expr.span,
"instead of prefixing all patterns with `&`, you can \
dereference the expression",
template);
});
}
}
}
@ -411,12 +410,11 @@ fn has_only_ref_pats(arms: &[Arm]) -> bool {
mapped.map_or(false, |v| v.iter().any(|el| *el))
}
fn match_template(cx: &LateContext, span: Span, source: MatchSource, op: &str, expr: &Expr) -> String {
let expr_snippet = snippet(cx, expr.span, "..");
fn match_template(span: Span, source: MatchSource, expr: Sugg) -> String {
match source {
MatchSource::Normal => format!("match {}{} {{ .. }}", op, expr_snippet),
MatchSource::IfLetDesugar { .. } => format!("if let .. = {}{} {{ .. }}", op, expr_snippet),
MatchSource::WhileLetDesugar => format!("while let .. = {}{} {{ .. }}", op, expr_snippet),
MatchSource::Normal => format!("match {} {{ .. }}", expr),
MatchSource::IfLetDesugar { .. } => format!("if let .. = {} {{ .. }}", expr),
MatchSource::WhileLetDesugar => format!("while let .. = {} {{ .. }}", expr),
MatchSource::ForLoopDesugar => span_bug!(span, "for loop desugared to match with &-patterns!"),
MatchSource::TryDesugar => span_bug!(span, "`?` operator desugared to match with &-patterns!"),
}

5
clippy_lints/src/utils/sugg.rs
View File

@ -134,6 +134,11 @@ impl<'a> Sugg<'a> {
make_unop("&mut ", self)
}
/// Convenience method to create the `*<expr>` suggestion.
pub fn deref(self) -> Sugg<'static> {
make_unop("*", self)
}
/// Convenience method to create the `<lhs>..<rhs>` or `<lhs>...<rhs>` suggestion.
pub fn range(self, end: Self, limit: ast::RangeLimits) -> Sugg<'static> {
match limit {

12
tests/compile-fail/matches.rs
View File

@ -112,7 +112,7 @@ fn match_bool() {
match test {
//~^ ERROR you seem to be trying to match on a boolean expression
//~| HELP try
//~| HELP consider
//~| SUGGESTION if test { 0 } else { 42 };
true => 0,
false => 42,
@ -121,7 +121,7 @@ fn match_bool() {
let option = 1;
match option == 1 {
//~^ ERROR you seem to be trying to match on a boolean expression
//~| HELP try
//~| HELP consider
//~| SUGGESTION if option == 1 { 1 } else { 0 };
true => 1,
false => 0,
@ -129,7 +129,7 @@ fn match_bool() {
match test {
//~^ ERROR you seem to be trying to match on a boolean expression
//~| HELP try
//~| HELP consider
//~| SUGGESTION if !test { println!("Noooo!"); };
true => (),
false => { println!("Noooo!"); }
@ -137,7 +137,7 @@ fn match_bool() {
match test {
//~^ ERROR you seem to be trying to match on a boolean expression
//~| HELP try
//~| HELP consider
//~| SUGGESTION if !test { println!("Noooo!"); };
false => { println!("Noooo!"); }
_ => (),
@ -145,7 +145,7 @@ fn match_bool() {
match test && test {
//~^ ERROR you seem to be trying to match on a boolean expression
//~| HELP try
//~| HELP consider
//~| SUGGESTION if !(test && test) { println!("Noooo!"); };
//~| ERROR equal expressions as operands
false => { println!("Noooo!"); }
@ -154,7 +154,7 @@ fn match_bool() {
match test {
//~^ ERROR you seem to be trying to match on a boolean expression
//~| HELP try
//~| HELP consider
//~| SUGGESTION if test { println!("Yes!"); } else { println!("Noooo!"); };
false => { println!("Noooo!"); }
true => { println!("Yes!"); }