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improve the suggestion of the lint unit-arg #5931

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merged 4 commits into from
Sep 10, 2020
Merged

improve the suggestion of the lint unit-arg #5931

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2ecc2ac
unit-arg - improve suggestion
tnielens Aug 20, 2020
f3ccbef
unit-arg - pr comments
tnielens Aug 26, 2020
b1f0e01
Merge branch 'master' into unit-arg
tnielens Sep 2, 2020
b220ddf
unit-arg - pr remarks
tnielens Sep 2, 2020
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88 changes: 50 additions & 38 deletions clippy_lints/src/types.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,8 +11,8 @@ use rustc_hir as hir;
use rustc_hir::intravisit::{walk_body, walk_expr, walk_ty, FnKind, NestedVisitorMap, Visitor};
use rustc_hir::{
BinOpKind, Block, Body, Expr, ExprKind, FnDecl, FnRetTy, FnSig, GenericArg, GenericParamKind, HirId, ImplItem,
ImplItemKind, Item, ItemKind, Lifetime, Local, MatchSource, MutTy, Mutability, QPath, Stmt, StmtKind, TraitFn,
TraitItem, TraitItemKind, TyKind, UnOp,
ImplItemKind, Item, ItemKind, Lifetime, Local, MatchSource, MutTy, Mutability, Node, QPath, Stmt, StmtKind,
TraitFn, TraitItem, TraitItemKind, TyKind, UnOp,
};
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::hir::map::Map;
Expand All @@ -29,10 +29,10 @@ use rustc_typeck::hir_ty_to_ty;
use crate::consts::{constant, Constant};
use crate::utils::paths;
use crate::utils::{
clip, comparisons, differing_macro_contexts, higher, in_constant, indent_of, int_bits, is_type_diagnostic_item,
clip, comparisons, differing_macro_contexts, higher, in_constant, int_bits, is_type_diagnostic_item,
last_path_segment, match_def_path, match_path, method_chain_args, multispan_sugg, numeric_literal::NumericLiteral,
qpath_res, sext, snippet, snippet_block_with_applicability, snippet_opt, snippet_with_applicability,
snippet_with_macro_callsite, span_lint, span_lint_and_help, span_lint_and_sugg, span_lint_and_then, unsext,
qpath_res, sext, snippet, snippet_opt, snippet_with_applicability, snippet_with_macro_callsite, span_lint,
span_lint_and_help, span_lint_and_sugg, span_lint_and_then, unsext,
};

declare_clippy_lint! {
Expand Down Expand Up @@ -844,43 +844,54 @@ fn lint_unit_args(cx: &LateContext<'_>, expr: &Expr<'_>, args_to_recover: &[&Exp
Applicability::MaybeIncorrect,
);
or = "or ";
applicability = Applicability::MaybeIncorrect;
});
let sugg = args_to_recover

let arg_snippets: Vec<String> = args_to_recover
.iter()
.filter_map(|arg| snippet_opt(cx, arg.span))
.collect();
let arg_snippets_without_empty_blocks: Vec<String> = args_to_recover
.iter()
.filter(|arg| !is_empty_block(arg))
.enumerate()
.map(|(i, arg)| {
let indent = if i == 0 {
0
} else {
indent_of(cx, expr.span).unwrap_or(0)
};
format!(
"{}{};",
" ".repeat(indent),
snippet_block_with_applicability(cx, arg.span, "..", Some(expr.span), &mut applicability)
)
})
.collect::<Vec<String>>();
let mut and = "";
if !sugg.is_empty() {
let plural = if sugg.len() > 1 { "s" } else { "" };
db.span_suggestion(
expr.span.with_hi(expr.span.lo()),
&format!("{}move the expression{} in front of the call...", or, plural),
format!("{}\n", sugg.join("\n")),
applicability,
);
and = "...and "
.filter_map(|arg| snippet_opt(cx, arg.span))
.collect();

if let Some(mut sugg) = snippet_opt(cx, expr.span) {
arg_snippets.iter().for_each(|arg| {
sugg = sugg.replacen(arg, "()", 1);
});
sugg = format!("{}{}{}", arg_snippets_without_empty_blocks.join("; "), "; ", sugg);
let parent_node = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(expr.hir_id));
if !matches!(parent_node, Some(Node::Block(_))) && !matches!(parent_node, Some(Node::Stmt(_))) {
// expr is not in a block statement or result expression position, wrap in a block
sugg = format!("{{ {} }}", sugg);
}

if arg_snippets_without_empty_blocks.is_empty() {
db.multipart_suggestion(
&format!("use {}unit literal{} instead", singular, plural),
args_to_recover
.iter()
.map(|arg| (arg.span, "()".to_string()))
.collect::<Vec<_>>(),
applicability,
);
} else {
let plural = arg_snippets_without_empty_blocks.len() > 1;
let empty_or_s = if plural { "s" } else { "" };
let it_or_them = if plural { "them" } else { "it" };
db.span_suggestion(
expr.span,
&format!(
"{}move the expression{} in front of the call and replace {} with the unit literal `()`",
or, empty_or_s, it_or_them
),
sugg,
applicability,
);
}
}
db.multipart_suggestion(
&format!("{}use {}unit literal{} instead", and, singular, plural),
args_to_recover
.iter()
.map(|arg| (arg.span, "()".to_string()))
.collect::<Vec<_>>(),
applicability,
);
},
);
}
Expand Down Expand Up @@ -2055,6 +2066,7 @@ impl PartialOrd for FullInt {
})
}
}

impl Ord for FullInt {
#[must_use]
fn cmp(&self, other: &Self) -> Ordering {
Expand Down
7 changes: 6 additions & 1 deletion tests/ui/unit_arg.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
#![warn(clippy::unit_arg)]
#![allow(clippy::no_effect, unused_must_use, unused_variables)]
#![allow(clippy::no_effect, unused_must_use, unused_variables, clippy::unused_unit)]

use std::fmt::Debug;

Expand Down Expand Up @@ -47,6 +47,11 @@ fn bad() {
foo(3);
},
);
// here Some(foo(2)) isn't the top level statement expression, wrap the suggestion in a block
None.or(Some(foo(2)));
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// in this case, the suggestion can be inlined, no need for a surrounding block
// foo(()); foo(()) instead of { foo(()); foo(()) }
foo(foo(()))
}

fn ok() {
Expand Down
111 changes: 53 additions & 58 deletions tests/ui/unit_arg.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -11,31 +11,23 @@ help: remove the semicolon from the last statement in the block
|
LL | 1
|
help: or move the expression in front of the call...
help: or move the expression in front of the call and replace it with the unit literal `()`
|
LL | {
LL | 1;
LL | };
LL | }; foo(());
|
help: ...and use a unit literal instead
|
LL | foo(());
| ^^

error: passing a unit value to a function
--> $DIR/unit_arg.rs:26:5
|
LL | foo(foo(1));
| ^^^^^^^^^^^
|
help: move the expression in front of the call...
|
LL | foo(1);
help: move the expression in front of the call and replace it with the unit literal `()`
|
help: ...and use a unit literal instead
|
LL | foo(());
| ^^
LL | foo(1); foo(());
| ^^^^^^^^^^^^^^^

error: passing a unit value to a function
--> $DIR/unit_arg.rs:27:5
Expand All @@ -50,17 +42,13 @@ help: remove the semicolon from the last statement in the block
|
LL | foo(2)
|
help: or move the expression in front of the call...
help: or move the expression in front of the call and replace it with the unit literal `()`
|
LL | {
LL | foo(1);
LL | foo(2);
LL | };
|
help: ...and use a unit literal instead
LL | }; foo(());
|
LL | foo(());
| ^^

error: passing a unit value to a function
--> $DIR/unit_arg.rs:32:5
Expand All @@ -74,32 +62,23 @@ help: remove the semicolon from the last statement in the block
|
LL | 1
|
help: or move the expression in front of the call...
help: or move the expression in front of the call and replace it with the unit literal `()`
|
LL | {
LL | 1;
LL | };
LL | }; b.bar(());
|
help: ...and use a unit literal instead
|
LL | b.bar(());
| ^^

error: passing unit values to a function
--> $DIR/unit_arg.rs:35:5
|
LL | taking_multiple_units(foo(0), foo(1));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
help: move the expressions in front of the call...
|
LL | foo(0);
LL | foo(1);
|
help: ...and use unit literals instead
help: move the expressions in front of the call and replace them with the unit literal `()`
|
LL | taking_multiple_units((), ());
| ^^ ^^
LL | foo(0); foo(1); taking_multiple_units((), ());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: passing unit values to a function
--> $DIR/unit_arg.rs:36:5
Expand All @@ -114,18 +93,13 @@ help: remove the semicolon from the last statement in the block
|
LL | foo(2)
|
help: or move the expressions in front of the call...
help: or move the expressions in front of the call and replace them with the unit literal `()`
|
LL | foo(0);
LL | {
LL | foo(0); {
LL | foo(1);
LL | foo(2);
LL | };
|
help: ...and use unit literals instead
LL | }; taking_multiple_units((), ());
|
LL | taking_multiple_units((), ());
| ^^ ^^

error: passing unit values to a function
--> $DIR/unit_arg.rs:40:5
Expand All @@ -147,35 +121,56 @@ help: remove the semicolon from the last statement in the block
|
LL | foo(3)
|
help: or move the expressions in front of the call...
help: or move the expressions in front of the call and replace them with the unit literal `()`
|
LL | {
LL | foo(0);
LL | foo(1);
LL | };
LL | {
LL | foo(2);
LL | foo(0);
LL | foo(1);
LL | }; {
LL | foo(2);
LL | foo(3);
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This looks weird

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There is still an indentation issue I must handle.

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Fixed

...
help: ...and use unit literals instead

error: use of `or` followed by a function call
--> $DIR/unit_arg.rs:51:10
|
LL | (),
LL | (),
LL | None.or(Some(foo(2)));
| ^^^^^^^^^^^^^^^^ help: try this: `or_else(|| Some(foo(2)))`
|
= note: `-D clippy::or-fun-call` implied by `-D warnings`
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error: passing a unit value to a function
--> $DIR/unit_arg.rs:82:5
--> $DIR/unit_arg.rs:51:13
|
LL | Some(foo(1))
LL | None.or(Some(foo(2)));
| ^^^^^^^^^^^^
|
help: move the expression in front of the call and replace it with the unit literal `()`
|
LL | None.or({ foo(2); Some(()) });
| ^^^^^^^^^^^^^^^^^^^^

error: passing a unit value to a function
--> $DIR/unit_arg.rs:54:5
|
LL | foo(foo(()))
| ^^^^^^^^^^^^
|
help: move the expression in front of the call...
help: move the expression in front of the call and replace it with the unit literal `()`
|
LL | foo(()); foo(())
|

error: passing a unit value to a function
--> $DIR/unit_arg.rs:87:5
|
LL | Some(foo(1))
| ^^^^^^^^^^^^
|
LL | foo(1);
help: move the expression in front of the call and replace it with the unit literal `()`
|
help: ...and use a unit literal instead
LL | foo(1); Some(())
|
LL | Some(())
| ^^

error: aborting due to 8 previous errors
error: aborting due to 11 previous errors

21 changes: 6 additions & 15 deletions tests/ui/unit_arg_empty_blocks.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -22,30 +22,21 @@ error: passing unit values to a function
LL | taking_two_units({}, foo(0));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
help: move the expression in front of the call...
help: move the expression in front of the call and replace it with the unit literal `()`
|
LL | foo(0);
|
help: ...and use unit literals instead
|
LL | taking_two_units((), ());
| ^^ ^^
LL | foo(0); taking_two_units((), ());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: passing unit values to a function
--> $DIR/unit_arg_empty_blocks.rs:18:5
|
LL | taking_three_units({}, foo(0), foo(1));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
help: move the expressions in front of the call...
|
LL | foo(0);
LL | foo(1);
|
help: ...and use unit literals instead
help: move the expressions in front of the call and replace them with the unit literal `()`
|
LL | taking_three_units((), (), ());
| ^^ ^^ ^^
LL | foo(0); foo(1); taking_three_units((), (), ());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 4 previous errors