316 lines
9.7 KiB
Rust
316 lines
9.7 KiB
Rust
use rustc::lint::*;
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use rustc::{declare_lint, lint_array};
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use syntax::ast::*;
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use syntax::tokenstream::{ThinTokenStream, TokenStream};
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use syntax::parse::{token, parser};
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use crate::utils::{span_lint, span_lint_and_sugg};
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/// **What it does:** This lint warns when you use `println!("")` to
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/// print a newline.
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///
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/// **Why is this bad?** You should use `println!()`, which is simpler.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// println!("");
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/// ```
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declare_clippy_lint! {
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pub PRINTLN_EMPTY_STRING,
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style,
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"using `println!(\"\")` with an empty string"
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}
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/// **What it does:** This lint warns when you use `print!()` with a format
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/// string that
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/// ends in a newline.
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///
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/// **Why is this bad?** You should use `println!()` instead, which appends the
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/// newline.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// print!("Hello {}!\n", name);
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/// ```
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declare_clippy_lint! {
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pub PRINT_WITH_NEWLINE,
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style,
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"using `print!()` with a format string that ends in a newline"
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}
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/// **What it does:** Checks for printing on *stdout*. The purpose of this lint
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/// is to catch debugging remnants.
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///
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/// **Why is this bad?** People often print on *stdout* while debugging an
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/// application and might forget to remove those prints afterward.
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///
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/// **Known problems:** Only catches `print!` and `println!` calls.
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///
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/// **Example:**
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/// ```rust
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/// println!("Hello world!");
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/// ```
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declare_clippy_lint! {
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pub PRINT_STDOUT,
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restriction,
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"printing on stdout"
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}
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/// **What it does:** Checks for use of `Debug` formatting. The purpose of this
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/// lint is to catch debugging remnants.
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///
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/// **Why is this bad?** The purpose of the `Debug` trait is to facilitate
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/// debugging Rust code. It should not be used in in user-facing output.
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///
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/// **Example:**
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/// ```rust
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/// println!("{:?}", foo);
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/// ```
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declare_clippy_lint! {
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pub USE_DEBUG,
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restriction,
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"use of `Debug`-based formatting"
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}
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/// **What it does:** This lint warns about the use of literals as `print!`/`println!` args.
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///
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/// **Why is this bad?** Using literals as `println!` args is inefficient
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/// (c.f., https://github.com/matthiaskrgr/rust-str-bench) and unnecessary
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/// (i.e., just put the literal in the format string)
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///
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/// **Known problems:** Will also warn with macro calls as arguments that expand to literals
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/// -- e.g., `println!("{}", env!("FOO"))`.
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///
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/// **Example:**
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/// ```rust
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/// println!("{}", "foo");
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/// ```
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declare_clippy_lint! {
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pub PRINT_LITERAL,
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style,
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"printing a literal with a format string"
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}
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/// **What it does:** This lint warns when you use `writeln!(buf, "")` to
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/// print a newline.
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///
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/// **Why is this bad?** You should use `writeln!(buf)`, which is simpler.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// writeln!("");
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/// ```
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declare_clippy_lint! {
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pub WRITELN_EMPTY_STRING,
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style,
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"using `writeln!(\"\")` with an empty string"
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}
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/// **What it does:** This lint warns when you use `write!()` with a format
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/// string that
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/// ends in a newline.
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///
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/// **Why is this bad?** You should use `writeln!()` instead, which appends the
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/// newline.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// write!(buf, "Hello {}!\n", name);
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/// ```
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declare_clippy_lint! {
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pub WRITE_WITH_NEWLINE,
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style,
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"using `write!()` with a format string that ends in a newline"
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}
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/// **What it does:** This lint warns about the use of literals as `write!`/`writeln!` args.
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///
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/// **Why is this bad?** Using literals as `writeln!` args is inefficient
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/// (c.f., https://github.com/matthiaskrgr/rust-str-bench) and unnecessary
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/// (i.e., just put the literal in the format string)
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///
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/// **Known problems:** Will also warn with macro calls as arguments that expand to literals
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/// -- e.g., `writeln!(buf, "{}", env!("FOO"))`.
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///
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/// **Example:**
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/// ```rust
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/// writeln!(buf, "{}", "foo");
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/// ```
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declare_clippy_lint! {
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pub WRITE_LITERAL,
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style,
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"writing a literal with a format string"
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}
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#[derive(Copy, Clone, Debug)]
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pub struct Pass;
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impl LintPass for Pass {
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fn get_lints(&self) -> LintArray {
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lint_array!(
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PRINT_WITH_NEWLINE,
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PRINTLN_EMPTY_STRING,
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PRINT_STDOUT,
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USE_DEBUG,
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PRINT_LITERAL,
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WRITE_WITH_NEWLINE,
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WRITELN_EMPTY_STRING,
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WRITE_LITERAL
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)
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}
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}
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impl EarlyLintPass for Pass {
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fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &Mac) {
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if mac.node.path == "println" {
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span_lint(cx, PRINT_STDOUT, mac.span, "use of `println!`");
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if let Some(fmtstr) = check_tts(cx, &mac.node.tts, false) {
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if fmtstr == "" {
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span_lint_and_sugg(
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cx,
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PRINTLN_EMPTY_STRING,
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mac.span,
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"using `println!(\"\")`",
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"replace it with",
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"println!()".to_string(),
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);
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}
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}
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} else if mac.node.path == "print" {
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span_lint(cx, PRINT_STDOUT, mac.span, "use of `print!`");
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if let Some(fmtstr) = check_tts(cx, &mac.node.tts, false) {
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if fmtstr.ends_with("\\n") {
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span_lint(cx, PRINT_WITH_NEWLINE, mac.span,
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"using `print!()` with a format string that ends in a \
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newline, consider using `println!()` instead");
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}
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}
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} else if mac.node.path == "write" {
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if let Some(fmtstr) = check_tts(cx, &mac.node.tts, true) {
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if fmtstr.ends_with("\\n") {
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span_lint(cx, WRITE_WITH_NEWLINE, mac.span,
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"using `write!()` with a format string that ends in a \
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newline, consider using `writeln!()` instead");
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}
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}
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} else if mac.node.path == "writeln" {
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if let Some(fmtstr) = check_tts(cx, &mac.node.tts, true) {
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if fmtstr == "" {
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span_lint_and_sugg(
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cx,
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WRITELN_EMPTY_STRING,
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mac.span,
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"using `writeln!(v, \"\")`",
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"replace it with",
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"writeln!(v)".to_string(),
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);
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}
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}
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}
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}
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}
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fn check_tts(cx: &EarlyContext<'a>, tts: &ThinTokenStream, is_write: bool) -> Option<String> {
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let tts = TokenStream::from(tts.clone());
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let mut parser = parser::Parser::new(
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&cx.sess.parse_sess,
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tts,
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None,
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false,
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false,
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);
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if is_write {
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// skip the initial write target
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parser.parse_expr().map_err(|mut err| err.cancel()).ok()?;
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// might be `writeln!(foo)`
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parser.expect(&token::Comma).map_err(|mut err| err.cancel()).ok()?;
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}
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let fmtstr = parser.parse_str().map_err(|mut err| err.cancel()).ok()?.0.to_string();
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use fmt_macros::*;
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let tmp = fmtstr.clone();
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let mut args = vec![];
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let mut fmt_parser = Parser::new(&tmp, None);
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while let Some(piece) = fmt_parser.next() {
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if !fmt_parser.errors.is_empty() {
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return None;
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}
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if let Piece::NextArgument(arg) = piece {
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if arg.format.ty == "?" {
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// FIXME: modify rustc's fmt string parser to give us the current span
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span_lint(cx, USE_DEBUG, parser.prev_span, "use of `Debug`-based formatting");
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}
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args.push(arg);
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}
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}
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let lint = if is_write {
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WRITE_LITERAL
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} else {
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PRINT_LITERAL
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};
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let mut idx = 0;
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loop {
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if !parser.eat(&token::Comma) {
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assert!(parser.eat(&token::Eof));
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return Some(fmtstr);
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}
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let expr = parser.parse_expr().map_err(|mut err| err.cancel()).ok()?;
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const SIMPLE: FormatSpec<'_> = FormatSpec {
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fill: None,
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align: AlignUnknown,
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flags: 0,
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precision: CountImplied,
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width: CountImplied,
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ty: "",
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};
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match &expr.node {
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ExprKind::Lit(_) => {
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let mut all_simple = true;
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let mut seen = false;
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for arg in &args {
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match arg.position {
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| ArgumentImplicitlyIs(n)
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| ArgumentIs(n)
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=> if n == idx {
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all_simple &= arg.format == SIMPLE;
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seen = true;
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},
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ArgumentNamed(_) => {},
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}
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}
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if all_simple && seen {
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span_lint(cx, lint, expr.span, "literal with an empty format string");
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}
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idx += 1;
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},
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ExprKind::Assign(lhs, rhs) => {
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if let ExprKind::Path(_, p) = &lhs.node {
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let mut all_simple = true;
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let mut seen = false;
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for arg in &args {
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match arg.position {
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| ArgumentImplicitlyIs(_)
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| ArgumentIs(_)
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=> {},
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ArgumentNamed(name) => if *p == name {
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seen = true;
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all_simple &= arg.format == SIMPLE;
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},
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}
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}
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if all_simple && seen {
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span_lint(cx, lint, rhs.span, "literal with an empty format string");
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}
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}
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},
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_ => idx += 1,
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}
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}
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}
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