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Don't panic

This commit is contained in:
Seo Sanghyeon 2015-11-25 13:57:50 +09:00
parent 746991572f
commit b1a0abe404
1 changed files with 13 additions and 7 deletions
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20
src/matches.rs
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@ -2,6 +2,7 @@ use rustc::lint::*;
use rustc_front::hir::*;
use rustc::middle::ty;
use syntax::ast::Lit_::LitBool;
use syntax::codemap::Span;
use utils::{snippet, span_lint, span_help_and_lint, in_external_macro, expr_block};
@ -113,12 +114,12 @@ impl LateLintPass for MatchPass {
// check preconditions for MATCH_REF_PATS
if has_only_ref_pats(arms) {
if let ExprAddrOf(Mutability::MutImmutable, ref inner) = ex.node {
let template = match_template(source, "", &snippet(cx, inner.span, ".."));
let template = match_template(cx, expr.span, source, "", inner);
span_lint(cx, MATCH_REF_PATS, expr.span, &format!(
"you don't need to add `&` to both the expression \
and the patterns: use `{}`", template));
} else {
let template = match_template(source, "*", &snippet(cx, ex.span, ".."));
let template = match_template(cx, expr.span, source, "*", ex);
span_lint(cx, MATCH_REF_PATS, expr.span, &format!(
"instead of prefixing all patterns with `&`, you can dereference the \
expression: `{}`", template));
@ -146,19 +147,24 @@ fn has_only_ref_pats(arms: &[Arm]) -> bool {
mapped.map_or(false, |v| v.iter().any(|el| *el))
}
fn match_template(source: MatchSource, op: &str, expr: &str) -> String {
fn match_template(cx: &LateContext,
span: Span,
source: MatchSource,
op: &str,
expr: &Expr) -> String {
let expr_snippet = snippet(cx, expr.span, "..");
match source {
MatchSource::Normal => {
format!("match {}{} {{ ...", op, expr)
format!("match {}{} {{ ...", op, expr_snippet)
}
MatchSource::IfLetDesugar { .. } => {
format!("if let ... = {}{} {{", op, expr)
format!("if let ... = {}{} {{", op, expr_snippet)
}
MatchSource::WhileLetDesugar => {
format!("while let ... = {}{} {{", op, expr)
format!("while let ... = {}{} {{", op, expr_snippet)
}
MatchSource::ForLoopDesugar => {
panic!("for loop desugared to match with &-patterns!")
cx.sess().span_bug(span, "for loop desugared to match with &-patterns!")
}
}
}