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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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107 changes: 70 additions & 37 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 @@ -31,8 +31,8 @@ use crate::utils::paths;
use crate::utils::{
clip, comparisons, differing_macro_contexts, higher, in_constant, indent_of, 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, trim_multiline, unsext,
};

declare_clippy_lint! {
Expand Down Expand Up @@ -802,6 +802,7 @@ impl<'tcx> LateLintPass<'tcx> for UnitArg {
}
}

#[allow(clippy::too_many_lines)]
fn lint_unit_args(cx: &LateContext<'_>, expr: &Expr<'_>, args_to_recover: &[&Expr<'_>]) {
let mut applicability = Applicability::MachineApplicable;
let (singular, plural) = if args_to_recover.len() > 1 {
Expand Down Expand Up @@ -844,43 +845,74 @@ 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 "
}
db.multipart_suggestion(
&format!("{}use {}unit literal{} instead", and, singular, plural),
args_to_recover
.filter_map(|arg| snippet_opt(cx, arg.span))
.collect();
let indent = indent_of(cx, expr.span).unwrap_or(0);

if let Some(expr_str) = snippet_opt(cx, expr.span) {
let expr_with_replacements = arg_snippets
.iter()
.map(|arg| (arg.span, "()".to_string()))
.collect::<Vec<_>>(),
applicability,
);
.fold(expr_str, |acc, arg| acc.replacen(arg, "()", 1));

// expr is not in a block statement or result expression position, wrap in a block
let parent_node = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(expr.hir_id));
let wrap_in_block =
!matches!(parent_node, Some(Node::Block(_))) && !matches!(parent_node, Some(Node::Stmt(_)));

let stmts_indent = if wrap_in_block { indent + 4 } else { indent };
let mut stmts_and_call = arg_snippets_without_empty_blocks.clone();
stmts_and_call.push(expr_with_replacements);
let mut stmts_and_call_str = stmts_and_call
.into_iter()
.enumerate()
.map(|(i, v)| {
let with_indent_prefix = if i > 0 { " ".repeat(stmts_indent) + &v } else { v };
trim_multiline(with_indent_prefix.into(), true, Some(stmts_indent)).into_owned()
})
.collect::<Vec<String>>()
.join(";\n");

if wrap_in_block {
stmts_and_call_str = " ".repeat(stmts_indent) + &stmts_and_call_str;
stmts_and_call_str = format!("{{\n{}\n{}}}", &stmts_and_call_str, " ".repeat(indent));
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Would it make sense to wrap this wrap_in_block handling code into its own function to get rid of the allow above?

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@tnielens tnielens Sep 2, 2020 •
edited
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I moved that logic out. That clarifies the code a bit 👍.
I had to modify and rename the trim_multiline utils method to let it indent code further as it only supported dedentation.

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in case you missed the notif @flip1995 (sorry if have no time atm)

}

let sugg = stmts_and_call_str;

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,
);
}
}
},
);
}
Expand Down Expand Up @@ -2055,6 +2087,7 @@ impl PartialOrd for FullInt {
})
}
}

impl Ord for FullInt {
#[must_use]
fn cmp(&self, other: &Self) -> Ordering {
Expand Down
2 changes: 1 addition & 1 deletion clippy_lints/src/utils/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -662,7 +662,7 @@ pub fn expr_block<'a, T: LintContext>(

/// Trim indentation from a multiline string with possibility of ignoring the
/// first line.
fn trim_multiline(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>) -> Cow<'_, str> {
pub fn trim_multiline(s: Cow<'_, str>, ignore_first: bool, indent: Option<usize>) -> Cow<'_, str> {
let s_space = trim_multiline_inner(s, ignore_first, indent, ' ');
let s_tab = trim_multiline_inner(s_space, ignore_first, indent, '\t');
trim_multiline_inner(s_tab, ignore_first, indent, ' ')
Expand Down
13 changes: 12 additions & 1 deletion tests/ui/unit_arg.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,11 @@
#![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,
clippy::or_fun_call
)]

use std::fmt::Debug;

Expand Down Expand Up @@ -47,6 +53,11 @@ 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
96 changes: 48 additions & 48 deletions tests/ui/unit_arg.stderr
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
error: passing a unit value to a function
--> $DIR/unit_arg.rs:23:5
--> $DIR/unit_arg.rs:29:5
|
LL | / foo({
LL | | 1;
Expand All @@ -11,34 +11,28 @@ 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 | };
|
help: ...and use a unit literal instead
|
LL | foo(());
| ^^
|

error: passing a unit value to a function
--> $DIR/unit_arg.rs:26:5
--> $DIR/unit_arg.rs:32:5
|
LL | foo(foo(1));
| ^^^^^^^^^^^
|
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(1);
|
help: ...and use a unit literal instead
|
LL | foo(());
| ^^
|

error: passing a unit value to a function
--> $DIR/unit_arg.rs:27:5
--> $DIR/unit_arg.rs:33:5
|
LL | / foo({
LL | | foo(1);
Expand All @@ -50,20 +44,17 @@ 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(());
| ^^
|

error: passing a unit value to a function
--> $DIR/unit_arg.rs:32:5
--> $DIR/unit_arg.rs:38:5
|
LL | / b.bar({
LL | | 1;
Expand All @@ -74,35 +65,29 @@ 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 | };
|
help: ...and use a unit literal instead
|
LL | b.bar(());
| ^^
|

error: passing unit values to a function
--> $DIR/unit_arg.rs:35:5
--> $DIR/unit_arg.rs:41:5
|
LL | taking_multiple_units(foo(0), foo(1));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
help: move the expressions in front of the call...
help: move the expressions in front of the call and replace them with the unit literal `()`
|
LL | foo(0);
LL | foo(1);
|
help: ...and use unit literals instead
|
LL | taking_multiple_units((), ());
| ^^ ^^
|

error: passing unit values to a function
--> $DIR/unit_arg.rs:36:5
--> $DIR/unit_arg.rs:42:5
|
LL | / taking_multiple_units(foo(0), {
LL | | foo(1);
Expand All @@ -114,21 +99,18 @@ 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(1);
LL | foo(2);
LL | };
|
help: ...and use unit literals instead
|
LL | taking_multiple_units((), ());
| ^^ ^^
|

error: passing unit values to a function
--> $DIR/unit_arg.rs:40:5
--> $DIR/unit_arg.rs:46:5
|
LL | / taking_multiple_units(
LL | | {
Expand All @@ -147,7 +129,7 @@ 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);
Expand All @@ -156,26 +138,44 @@ LL | };
LL | {
LL | foo(2);
...
help: ...and use unit literals instead

error: passing a unit value to a function
--> $DIR/unit_arg.rs:57:13
|
LL | None.or(Some(foo(2)));
| ^^^^^^^^^^^^
|
LL | (),
LL | (),
help: move the expression in front of the call and replace it with the unit literal `()`
|
LL | None.or({
LL | foo(2);
LL | Some(())
LL | });
|

error: passing a unit value to a function
--> $DIR/unit_arg.rs:82:5
--> $DIR/unit_arg.rs:60:5
|
LL | Some(foo(1))
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(1);
LL | foo(());
LL | foo(())
|
help: ...and use a unit literal instead

error: passing a unit value to a function
--> $DIR/unit_arg.rs:93:5
|
LL | Some(foo(1))
| ^^^^^^^^^^^^
|
help: move the expression in front of the call and replace it with the unit literal `()`
|
LL | foo(1);
LL | Some(())
| ^^
|

error: aborting due to 8 previous errors
error: aborting due to 10 previous errors

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