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use rustc::hir::*;
use rustc::hir::map::Node::{NodeItem, NodeImplItem};
use rustc::lint::*;
use utils::paths;
use utils::{is_expn_of, match_def_path, resolve_node, span_lint, match_path};
use format::get_argument_fmtstr_parts;
/// **What it does:** This lint warns when you using `print!()` with a format
/// string that
/// ends in a newline.
///
/// **Why is this bad?** You should use `println!()` instead, which appends the
/// newline.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// print!("Hello {}!\n", name);
/// ```
declare_lint! {
pub PRINT_WITH_NEWLINE,
Warn,
"using `print!()` with a format string that ends in a newline"
}
/// **What it does:** Checks for printing on *stdout*. The purpose of this lint
/// is to catch debugging remnants.
///
/// **Why is this bad?** People often print on *stdout* while debugging an
/// application and might forget to remove those prints afterward.
///
/// **Known problems:** Only catches `print!` and `println!` calls.
///
/// **Example:**
/// ```rust
/// println!("Hello world!");
/// ```
declare_lint! {
pub PRINT_STDOUT,
Allow,
"printing on stdout"
}
/// **What it does:** Checks for use of `Debug` formatting. The purpose of this
/// lint is to catch debugging remnants.
///
/// **Why is this bad?** The purpose of the `Debug` trait is to facilitate
/// debugging Rust code. It should not be used in in user-facing output.
///
/// **Example:**
/// ```rust
/// println!("{:?}", foo);
/// ```
declare_lint! {
pub USE_DEBUG,
Allow,
"use of `Debug`-based formatting"
}
#[derive(Copy, Clone, Debug)]
pub struct Pass;
impl LintPass for Pass {
fn get_lints(&self) -> LintArray {
lint_array!(PRINT_WITH_NEWLINE, PRINT_STDOUT, USE_DEBUG)
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
if_let_chain! {[
let ExprCall(ref fun, ref args) = expr.node,
let ExprPath(ref qpath) = fun.node,
], {
let fun = resolve_node(cx, qpath, fun.hir_id);
let fun_id = fun.def_id();
// Search for `std::io::_print(..)` which is unique in a
// `print!` expansion.
if match_def_path(cx.tcx, fun_id, &paths::IO_PRINT) {
if let Some(span) = is_expn_of(expr.span, "print") {
// `println!` uses `print!`.
let (span, name) = match is_expn_of(span, "println") {
Some(span) => (span, "println"),
None => (span, "print"),
};
span_lint(cx, PRINT_STDOUT, span, &format!("use of `{}!`", name));
// Check print! with format string ending in "\n".
if_let_chain!{[
name == "print",
// ensure we're calling Arguments::new_v1
args.len() == 1,
let ExprCall(ref args_fun, ref args_args) = args[0].node,
let ExprPath(ref qpath) = args_fun.node,
match_def_path(cx.tcx,
resolve_node(cx, qpath, args_fun.hir_id).def_id(),
&paths::FMT_ARGUMENTS_NEWV1),
args_args.len() == 2,
let ExprAddrOf(_, ref match_expr) = args_args[1].node,
let ExprMatch(ref args, _, _) = match_expr.node,
let ExprTup(ref args) = args.node,
// collect the format string parts and check the last one
let Some(fmtstrs) = get_argument_fmtstr_parts(cx, &args_args[0]),
let Some(last_str) = fmtstrs.last(),
let Some('\n') = last_str.chars().last(),
// "foo{}bar" is made into two strings + one argument,
// if the format string starts with `{}` (eg. "{}foo"),
// the string array is prepended an empty string "".
// We only want to check the last string after any `{}`:
args.len() < fmtstrs.len(),
], {
span_lint(cx, PRINT_WITH_NEWLINE, span,
"using `print!()` with a format string that ends in a \
newline, consider using `println!()` instead");
}}
}
}
// Search for something like
// `::std::fmt::ArgumentV1::new(__arg0, ::std::fmt::Debug::fmt)`
else if args.len() == 2 && match_def_path(cx.tcx, fun_id, &paths::FMT_ARGUMENTV1_NEW) {
if let ExprPath(ref qpath) = args[1].node {
let def_id = cx.tables.qpath_def(qpath, args[1].hir_id).def_id();
if match_def_path(cx.tcx, def_id, &paths::DEBUG_FMT_METHOD) && !is_in_debug_impl(cx, expr) &&
is_expn_of(expr.span, "panic").is_none() {
span_lint(cx, USE_DEBUG, args[0].span, "use of `Debug`-based formatting");
}
}
}
}}
}
}
fn is_in_debug_impl(cx: &LateContext, expr: &Expr) -> bool {
let map = &cx.tcx.hir;
// `fmt` method
if let Some(NodeImplItem(item)) = map.find(map.get_parent(expr.id)) {
// `Debug` impl
if let Some(NodeItem(item)) = map.find(map.get_parent(item.id)) {
if let ItemImpl(_, _, _, _, Some(ref tr), _, _) = item.node {
return match_path(&tr.path, &["Debug"]);
}
}
}
false
}