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Auto merge of #6367 - justjosias:6348-print-stderr, r=ebroto

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Add lint print_stderr

Resolves #6348
Almost identical to print_stdout, this lint applies to the `eprintln!` and `eprint!` macros rather than `println!` and `print!`.

changelog: Add new lint [`print_stderr`]. [`println_empty_string`] and [`print_with_newline`] now apply to `eprint!()` and `eprintln!()` respectively.
This commit is contained in:
bors 2020-12-08 22:22:49 +00:00
commit b02b0c737a
10 changed files with 294 additions and 38 deletions
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1
CHANGELOG.md
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@ -2006,6 +2006,7 @@ Released 2018-09-13
[`possible_missing_comma`]: https://rust-lang.github.io/rust-clippy/master/index.html#possible_missing_comma
[`precedence`]: https://rust-lang.github.io/rust-clippy/master/index.html#precedence
[`print_literal`]: https://rust-lang.github.io/rust-clippy/master/index.html#print_literal
[`print_stderr`]: https://rust-lang.github.io/rust-clippy/master/index.html#print_stderr
[`print_stdout`]: https://rust-lang.github.io/rust-clippy/master/index.html#print_stdout
[`print_with_newline`]: https://rust-lang.github.io/rust-clippy/master/index.html#print_with_newline
[`println_empty_string`]: https://rust-lang.github.io/rust-clippy/master/index.html#println_empty_string

2
clippy_lints/src/lib.rs
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@ -936,6 +936,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
&wildcard_imports::WILDCARD_IMPORTS,
&write::PRINTLN_EMPTY_STRING,
&write::PRINT_LITERAL,
&write::PRINT_STDERR,
&write::PRINT_STDOUT,
&write::PRINT_WITH_NEWLINE,
&write::USE_DEBUG,
@ -1250,6 +1251,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&types::RC_BUFFER),
LintId::of(&unwrap_in_result::UNWRAP_IN_RESULT),
LintId::of(&verbose_file_reads::VERBOSE_FILE_READS),
LintId::of(&write::PRINT_STDERR),
LintId::of(&write::PRINT_STDOUT),
LintId::of(&write::USE_DEBUG),
]);

107
clippy_lints/src/write.rs
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@ -75,6 +75,24 @@ declare_clippy_lint! {
"printing on stdout"
}
declare_clippy_lint! {
/// **What it does:** Checks for printing on *stderr*. The purpose of this lint
/// is to catch debugging remnants.
///
/// **Why is this bad?** People often print on *stderr* while debugging an
/// application and might forget to remove those prints afterward.
///
/// **Known problems:** Only catches `eprint!` and `eprintln!` calls.
///
/// **Example:**
/// ```rust
/// eprintln!("Hello world!");
/// ```
pub PRINT_STDERR,
restriction,
"printing on stderr"
}
declare_clippy_lint! {
/// **What it does:** Checks for use of `Debug` formatting. The purpose of this
/// lint is to catch debugging remnants.
@ -201,6 +219,7 @@ impl_lint_pass!(Write => [
PRINT_WITH_NEWLINE,
PRINTLN_EMPTY_STRING,
PRINT_STDOUT,
PRINT_STDERR,
USE_DEBUG,
PRINT_LITERAL,
WRITE_WITH_NEWLINE,
@ -243,47 +262,22 @@ impl EarlyLintPass for Write {
.map_or(false, |crate_name| crate_name == "build_script_build")
}
if mac.path == sym!(println) {
if !is_build_script(cx) {
span_lint(cx, PRINT_STDOUT, mac.span(), "use of `println!`");
}
if let (Some(fmt_str), _) = self.check_tts(cx, mac.args.inner_tokens(), false) {
if fmt_str.symbol == Symbol::intern("") {
span_lint_and_sugg(
cx,
PRINTLN_EMPTY_STRING,
mac.span(),
"using `println!(\"\")`",
"replace it with",
"println!()".to_string(),
Applicability::MachineApplicable,
);
}
}
} else if mac.path == sym!(print) {
if mac.path == sym!(print) {
if !is_build_script(cx) {
span_lint(cx, PRINT_STDOUT, mac.span(), "use of `print!`");
}
if let (Some(fmt_str), _) = self.check_tts(cx, mac.args.inner_tokens(), false) {
if check_newlines(&fmt_str) {
span_lint_and_then(
cx,
PRINT_WITH_NEWLINE,
mac.span(),
"using `print!()` with a format string that ends in a single newline",
|err| {
err.multipart_suggestion(
"use `println!` instead",
vec![
(mac.path.span, String::from("println")),
(newline_span(&fmt_str), String::new()),
],
Applicability::MachineApplicable,
);
},
);
}
self.lint_print_with_newline(cx, mac);
} else if mac.path == sym!(println) {
if !is_build_script(cx) {
span_lint(cx, PRINT_STDOUT, mac.span(), "use of `println!`");
}
self.lint_println_empty_string(cx, mac);
} else if mac.path == sym!(eprint) {
span_lint(cx, PRINT_STDERR, mac.span(), "use of `eprint!`");
self.lint_print_with_newline(cx, mac);
} else if mac.path == sym!(eprintln) {
span_lint(cx, PRINT_STDERR, mac.span(), "use of `eprintln!`");
self.lint_println_empty_string(cx, mac);
} else if mac.path == sym!(write) {
if let (Some(fmt_str), _) = self.check_tts(cx, mac.args.inner_tokens(), true) {
if check_newlines(&fmt_str) {
@ -487,6 +481,45 @@ impl Write {
}
}
}
fn lint_println_empty_string(&self, cx: &EarlyContext<'_>, mac: &MacCall) {
if let (Some(fmt_str), _) = self.check_tts(cx, mac.args.inner_tokens(), false) {
if fmt_str.symbol == Symbol::intern("") {
let name = mac.path.segments[0].ident.name;
span_lint_and_sugg(
cx,
PRINTLN_EMPTY_STRING,
mac.span(),
&format!("using `{}!(\"\")`", name),
"replace it with",
format!("{}!()", name),
Applicability::MachineApplicable,
);
}
}
}
fn lint_print_with_newline(&self, cx: &EarlyContext<'_>, mac: &MacCall) {
if let (Some(fmt_str), _) = self.check_tts(cx, mac.args.inner_tokens(), false) {
if check_newlines(&fmt_str) {
let name = mac.path.segments[0].ident.name;
let suggested = format!("{}ln", name);
span_lint_and_then(
cx,
PRINT_WITH_NEWLINE,
mac.span(),
&format!("using `{}!()` with a format string that ends in a single newline", name),
|err| {
err.multipart_suggestion(
&format!("use `{}!` instead", suggested),
vec![(mac.path.span, suggested), (newline_span(&fmt_str), String::new())],
Applicability::MachineApplicable,
);
},
);
}
}
}
}
/// Checks if the format string contains a single newline that terminates it.

49
tests/ui/eprint_with_newline.rs Normal file
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@ -0,0 +1,49 @@
#![allow(clippy::print_literal)]
#![warn(clippy::print_with_newline)]
fn main() {
eprint!("Hello\n");
eprint!("Hello {}\n", "world");
eprint!("Hello {} {}\n", "world", "#2");
eprint!("{}\n", 1265);
eprint!("\n");
// these are all fine
eprint!("");
eprint!("Hello");
eprintln!("Hello");
eprintln!("Hello\n");
eprintln!("Hello {}\n", "world");
eprint!("Issue\n{}", 1265);
eprint!("{}", 1265);
eprint!("\n{}", 1275);
eprint!("\n\n");
eprint!("like eof\n\n");
eprint!("Hello {} {}\n\n", "world", "#2");
eprintln!("\ndon't\nwarn\nfor\nmultiple\nnewlines\n"); // #3126
eprintln!("\nbla\n\n"); // #3126
// Escaping
eprint!("\\n"); // #3514
eprint!("\\\n"); // should fail
eprint!("\\\\n");
// Raw strings
eprint!(r"\n"); // #3778
// Literal newlines should also fail
eprint!(
"
"
);
eprint!(
r"
"
);
// Don't warn on CRLF (#4208)
eprint!("\r\n");
eprint!("foo\r\n");
eprint!("\\r\n"); //~ ERROR
eprint!("foo\rbar\n") // ~ ERROR
}

121
tests/ui/eprint_with_newline.stderr Normal file
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@ -0,0 +1,121 @@
error: using `eprint!()` with a format string that ends in a single newline
--> $DIR/eprint_with_newline.rs:5:5
|
LL | eprint!("Hello/n");
| ^^^^^^^^^^^^^^^^^^
|
= note: `-D clippy::print-with-newline` implied by `-D warnings`
help: use `eprintln!` instead
|
LL | eprintln!("Hello");
| ^^^^^^^^ --
error: using `eprint!()` with a format string that ends in a single newline
--> $DIR/eprint_with_newline.rs:6:5
|
LL | eprint!("Hello {}/n", "world");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
help: use `eprintln!` instead
|
LL | eprintln!("Hello {}", "world");
| ^^^^^^^^ --
error: using `eprint!()` with a format string that ends in a single newline
--> $DIR/eprint_with_newline.rs:7:5
|
LL | eprint!("Hello {} {}/n", "world", "#2");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
help: use `eprintln!` instead
|
LL | eprintln!("Hello {} {}", "world", "#2");
| ^^^^^^^^ --
error: using `eprint!()` with a format string that ends in a single newline
--> $DIR/eprint_with_newline.rs:8:5
|
LL | eprint!("{}/n", 1265);
| ^^^^^^^^^^^^^^^^^^^^^
|
help: use `eprintln!` instead
|
LL | eprintln!("{}", 1265);
| ^^^^^^^^ --
error: using `eprint!()` with a format string that ends in a single newline
--> $DIR/eprint_with_newline.rs:9:5
|
LL | eprint!("/n");
| ^^^^^^^^^^^^^
|
help: use `eprintln!` instead
|
LL | eprintln!();
| ^^^^^^^^ --
error: using `eprint!()` with a format string that ends in a single newline
--> $DIR/eprint_with_newline.rs:28:5
|
LL | eprint!("//n"); // should fail
| ^^^^^^^^^^^^^^^
|
help: use `eprintln!` instead
|
LL | eprintln!("/"); // should fail
| ^^^^^^^^ --
error: using `eprint!()` with a format string that ends in a single newline
--> $DIR/eprint_with_newline.rs:35:5
|
LL | / eprint!(
LL | | "
LL | | "
LL | | );
| |_____^
|
help: use `eprintln!` instead
|
LL | eprintln!(
LL | ""
|
error: using `eprint!()` with a format string that ends in a single newline
--> $DIR/eprint_with_newline.rs:39:5
|
LL | / eprint!(
LL | | r"
LL | | "
LL | | );
| |_____^
|
help: use `eprintln!` instead
|
LL | eprintln!(
LL | r""
|
error: using `eprint!()` with a format string that ends in a single newline
--> $DIR/eprint_with_newline.rs:47:5
|
LL | eprint!("/r/n"); //~ ERROR
| ^^^^^^^^^^^^^^^^
|
help: use `eprintln!` instead
|
LL | eprintln!("/r"); //~ ERROR
| ^^^^^^^^ --
error: using `eprint!()` with a format string that ends in a single newline
--> $DIR/eprint_with_newline.rs:48:5
|
LL | eprint!("foo/rbar/n") // ~ ERROR
| ^^^^^^^^^^^^^^^^^^^^^
|
help: use `eprintln!` instead
|
LL | eprintln!("foo/rbar") // ~ ERROR
| ^^^^^^^^ --
error: aborting due to 10 previous errors

8
tests/ui/print_stderr.rs Normal file
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@ -0,0 +1,8 @@
#![warn(clippy::print_stderr)]
fn main() {
eprintln!("Hello");
println!("This should not do anything");
eprint!("World");
print!("Nor should this");
}

16
tests/ui/print_stderr.stderr Normal file
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@ -0,0 +1,16 @@
error: use of `eprintln!`
--> $DIR/print_stderr.rs:4:5
|
LL | eprintln!("Hello");
| ^^^^^^^^^^^^^^^^^^
|
= note: `-D clippy::print-stderr` implied by `-D warnings`
error: use of `eprint!`
--> $DIR/print_stderr.rs:6:5
|
LL | eprint!("World");
| ^^^^^^^^^^^^^^^^
error: aborting due to 2 previous errors

7
tests/ui/println_empty_string.fixed
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@ -8,4 +8,11 @@ fn main() {
match "a" {
_ => println!(),
}
eprintln!();
eprintln!();
match "a" {
_ => eprintln!(),
}
}

7
tests/ui/println_empty_string.rs
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@ -8,4 +8,11 @@ fn main() {
match "a" {
_ => println!(""),
}
eprintln!();
eprintln!("");
match "a" {
_ => eprintln!(""),
}
}

14
tests/ui/println_empty_string.stderr
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@ -12,5 +12,17 @@ error: using `println!("")`
LL | _ => println!(""),
| ^^^^^^^^^^^^ help: replace it with: `println!()`
error: aborting due to 2 previous errors
error: using `eprintln!("")`
--> $DIR/println_empty_string.rs:13:5
|
LL | eprintln!("");
| ^^^^^^^^^^^^^ help: replace it with: `eprintln!()`
error: using `eprintln!("")`
--> $DIR/println_empty_string.rs:16:14
|
LL | _ => eprintln!(""),
| ^^^^^^^^^^^^^ help: replace it with: `eprintln!()`
error: aborting due to 4 previous errors