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https://github.com/rust-lang/rust-clippy
synced 2024-11-10 23:24:24 +00:00
Add PRINTLN_EMPTY_STRING lint.
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4d9ed8beef
commit
22f3ca0e2c
4 changed files with 78 additions and 16 deletions
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@ -530,6 +530,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
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partialeq_ne_impl::PARTIALEQ_NE_IMPL,
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precedence::PRECEDENCE,
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print::PRINT_WITH_NEWLINE,
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print::PRINTLN_EMPTY_STRING,
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ptr::CMP_NULL,
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ptr::MUT_FROM_REF,
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ptr::PTR_ARG,
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@ -1,11 +1,30 @@
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use std::ops::Deref;
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use rustc::hir::*;
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use rustc::hir::map::Node::{NodeImplItem, NodeItem};
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use rustc::lint::*;
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use syntax::ast::LitKind;
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use syntax::symbol::InternedString;
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use syntax_pos::Span;
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use utils::{is_expn_of, match_def_path, match_path, resolve_node, span_lint};
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use utils::{paths, opt_def_id};
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/// **What it does:** This lint warns when you using `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_lint! {
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pub PRINTLN_EMPTY_STRING,
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Warn,
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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:** This lint warns when you using `print!()` with a format
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/// string that
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/// ends in a newline.
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@ -64,7 +83,7 @@ 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!(PRINT_WITH_NEWLINE, PRINT_STDOUT, USE_DEBUG)
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lint_array!(PRINT_WITH_NEWLINE, PRINTLN_EMPTY_STRING, PRINT_STDOUT, USE_DEBUG)
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}
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}
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@ -88,10 +107,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
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span_lint(cx, PRINT_STDOUT, span, &format!("use of `{}!`", name));
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// Check print! with format string ending in "\n".
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if_let_chain!{[
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name == "print",
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// ensure we're calling Arguments::new_v1
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args.len() == 1,
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let ExprCall(ref args_fun, ref args_args) = args[0].node,
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@ -102,20 +118,13 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
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let ExprAddrOf(_, ref match_expr) = args_args[1].node,
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let ExprMatch(ref args, _, _) = match_expr.node,
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let ExprTup(ref args) = args.node,
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// collect the format string parts and check the last one
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let Some((fmtstr, fmtlen)) = get_argument_fmtstr_parts(&args_args[0]),
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let Some('\n') = fmtstr.chars().last(),
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// "foo{}bar" is made into two strings + one argument,
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// if the format string starts with `{}` (eg. "{}foo"),
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// the string array is prepended an empty string "".
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// We only want to check the last string after any `{}`:
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args.len() < fmtlen,
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], {
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span_lint(cx, PRINT_WITH_NEWLINE, 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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match name {
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"print" => check_print(cx, span, args, fmtstr, fmtlen),
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"println" => check_println(cx, span, fmtstr, fmtlen),
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_ => (),
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}
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}}
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}
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}
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@ -135,6 +144,46 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
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}
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}
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// Check for print!("... \n", ...).
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fn check_print<'a, 'tcx>(
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cx: &LateContext<'a, 'tcx>,
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span: Span,
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args: &HirVec<Expr>,
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fmtstr: InternedString,
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fmtlen: usize,
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) {
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if_let_chain!{[
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// check the final format string part
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let Some('\n') = fmtstr.chars().last(),
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// "foo{}bar" is made into two strings + one argument,
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// if the format string starts with `{}` (eg. "{}foo"),
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// the string array is prepended an empty string "".
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// We only want to check the last string after any `{}`:
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args.len() < fmtlen,
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], {
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span_lint(cx, PRINT_WITH_NEWLINE, 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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/// Check for println!("")
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fn check_println<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, span: Span, fmtstr: InternedString, fmtlen: usize) {
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if_let_chain!{[
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// check that the string is empty
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fmtlen == 1,
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fmtstr.deref() == "\n",
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// check the presence of that string
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let Ok(snippet) = cx.sess().codemap().span_to_snippet(span),
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snippet.contains("\"\""),
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], {
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span_lint(cx, PRINT_WITH_NEWLINE, span,
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"using `println!(\"\")`, consider using `println!()` instead");
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}}
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}
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fn is_in_debug_impl(cx: &LateContext, expr: &Expr) -> bool {
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let map = &cx.tcx.hir;
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4
tests/ui/println_empty_string.rs
Normal file
4
tests/ui/println_empty_string.rs
Normal file
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@ -0,0 +1,4 @@
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fn main() {
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println!();
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println!("");
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}
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8
tests/ui/println_empty_string.stderr
Normal file
8
tests/ui/println_empty_string.stderr
Normal file
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@ -0,0 +1,8 @@
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error: using `println!("")`, consider using `println!()` instead
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--> $DIR/println_empty_string.rs:3:5
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3 | println!("");
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| ^^^^^^^^^^^^^
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= note: `-D print-with-newline` implied by `-D warnings`
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