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Add for_loop_over_result lint

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This commit is contained in:
Devon Hollowood 2016-01-29 15:15:57 -08:00
parent f5cc94c96a
commit 405d7c691e
4 changed files with 74 additions and 15 deletions
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1
src/lib.rs
View file

@ -193,6 +193,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
loops::EXPLICIT_COUNTER_LOOP,
loops::EXPLICIT_ITER_LOOP,
loops::FOR_LOOP_OVER_OPTION,
loops::FOR_LOOP_OVER_RESULT,
loops::ITER_NEXT_LOOP,
loops::NEEDLESS_RANGE_LOOP,
loops::REVERSE_RANGE_LOOP,

35
src/loops.rs
View file

@ -11,7 +11,7 @@ use std::collections::{HashSet, HashMap};
use utils::{snippet, span_lint, get_parent_expr, match_trait_method, match_type, in_external_macro, expr_block,
span_help_and_lint, is_integer_literal, get_enclosing_block};
use utils::{HASHMAP_PATH, VEC_PATH, LL_PATH, OPTION_PATH};
use utils::{HASHMAP_PATH, VEC_PATH, LL_PATH, OPTION_PATH, RESULT_PATH};
/// **What it does:** This lint checks for looping over the range of `0..len` of some collection just to get the values by index. It is `Warn` by default.
///
@ -48,7 +48,7 @@ declare_lint!{ pub EXPLICIT_ITER_LOOP, Warn,
declare_lint!{ pub ITER_NEXT_LOOP, Warn,
"for-looping over `_.next()` which is probably not intended" }
/// **What it does:** This lint checks for `for` loops over Option values. It is `Warn` by default.
/// **What it does:** This lint checks for `for` loops over `Option` values. It is `Warn` by default.
///
/// **Why is this bad?** Readability. This is more clearly expressed as an `if let`.
///
@ -56,7 +56,17 @@ declare_lint!{ pub ITER_NEXT_LOOP, Warn,
///
/// **Example:** `for x in option { .. }`. This should be `if let Some(x) = option { .. }`.
declare_lint!{ pub FOR_LOOP_OVER_OPTION, Warn,
"for-looping over an Option, which is more clear as an `if let`" }
"for-looping over an `Option`, which is more clearly expressed as an `if let`" }
/// **What it does:** This lint checks for `for` loops over `Result` values. It is `Warn` by default.
///
/// **Why is this bad?** Readability. This is more clearly expressed as an `if let`.
///
/// **Known problems:** None
///
/// **Example:** `for x in result { .. }`. This should be `if let Ok(x) = result { .. }`.
declare_lint!{ pub FOR_LOOP_OVER_RESULT, Warn,
"for-looping over a `Result`, which is more clearly expressed as an `if let`" }
/// **What it does:** This lint detects `loop + match` combinations that are easier written as a `while let` loop. It is `Warn` by default.
///
@ -417,24 +427,35 @@ fn check_for_loop_arg(cx: &LateContext, pat: &Pat, arg: &Expr, expr: &Expr) {
}
}
if !next_loop_linted {
check_option_looping(cx, pat, arg);
check_arg_type(cx, pat, arg);
}
}
/// Check for `for` loops over `Option`s
fn check_option_looping(cx: &LateContext, pat: &Pat, arg: &Expr) {
/// Check for `for` loops over `Option`s and `Results`
fn check_arg_type(cx: &LateContext, pat: &Pat, arg: &Expr) {
let ty = cx.tcx.expr_ty(arg);
if match_type(cx, ty, &OPTION_PATH) {
span_help_and_lint(
cx,
FOR_LOOP_OVER_OPTION,
arg.span,
&format!("for loop over `{0}`, which is an Option. This is more readably written as \
&format!("for loop over `{0}`, which is an `Option`. This is more readably written as \
an `if let` statement.", snippet(cx, arg.span, "_")),
&format!("consider replacing `for {0} in {1}` with `if let Some({0}) = {1}`",
snippet(cx, pat.span, "_"), snippet(cx, arg.span, "_"))
);
}
else if match_type(cx, ty, &RESULT_PATH) {
span_help_and_lint(
cx,
FOR_LOOP_OVER_RESULT,
arg.span,
&format!("for loop over `{0}`, which is a `Result`. This is more readably written as \
an `if let` statement.", snippet(cx, arg.span, "_")),
&format!("consider replacing `for {0} in {1}` with `if let Ok({0}) = {1}`",
snippet(cx, pat.span, "_"), snippet(cx, arg.span, "_"))
);
}
}
fn check_for_loop_explicit_counter(cx: &LateContext, arg: &Expr, body: &Expr, expr: &Expr) {