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@merelymyself
merelymyself committed Jun 4, 2022
1 parent e897196 commit 36ec166
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Showing 3 changed files with 60 additions and 42 deletions.
77 changes: 37 additions & 40 deletions clippy_lints/src/path_from_format.rs
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Original file line number Diff line number Diff line change
@@ -1,13 +1,12 @@
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet;
use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_help};
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::ty::is_type_diagnostic_item;
use clippy_utils::macros::{root_macro_call, FormatArgsExpn};
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::sym;
use std::fmt::Write as _;

declare_clippy_lint! {
/// ### What it does
Expand Down Expand Up @@ -46,55 +45,53 @@ impl<'tcx> LateLintPass<'tcx> for PathFromFormat {
if let Some(macro_call) = root_macro_call(args[0].span);
if cx.tcx.item_name(macro_call.def_id) == sym::format;
if let Some(format_args) = FormatArgsExpn::find_nested(cx, &args[0], macro_call.expn);
let mut applicability = Applicability::MachineApplicable;
let format_args_snip = snippet_with_applicability(cx, format_args.inputs_span(), "..", &mut applicability);
if let Some(end_of_literal) = format_args_snip.find("\",");
then {
let full_expr = snippet(cx, expr.span, "error").to_string();
let split_expr: Vec<&str> = full_expr.split('!').collect();
let args_to_macro = split_expr[1];
let replaced = args_to_macro.replace('(', "").replace(')', "");
let unformatted: Vec<&str> = replaced.split(',').collect();
let mut push_targets: Vec<String> = Vec::new();
let mut temp_string = String::new();
for c in unformatted[0].chars() {
if c == '/' || c == '\\' {
push_targets.push(temp_string.clone());
temp_string = String::new();
}
else if c == '}' {
temp_string.push_str(&unformatted[1].replace(' ', ""));
}
else if c != '{' && c != '"' {
temp_string.push(c);
}
}
if !temp_string.is_empty() {
push_targets.push(temp_string.clone());
temp_string = String::new();
let (literal, vars) = format_args_snip.split_at(end_of_literal);
let mut literal = literal.to_string();
literal.remove(0);
let v: Vec<&str> = literal.split("{}").collect();
let real_vars = vars.strip_prefix("\", ").unwrap_or(vars);
if v.len() != 2 || real_vars.contains(',') {
span_lint_and_help(
cx,
PATH_FROM_FORMAT,
expr.span,
"`format!(..)` used to form `PathBuf`",
None,
"consider using `.join()` to avoid the extra allocation",
);
return;
}
for target in push_targets {
let target_processed =
if target == unformatted[1].replace(' ', "") {
target
let sugg = {
if v[0].is_empty() {
let mut str1 = v[1].to_string();
if str1.starts_with('\\') || str1.starts_with('/') {
str1.remove(0);
}
else {
let mut s = String::from("\"");
s.push_str(&target);
s.push('"');
s
};
if temp_string.is_empty() {
let _ = write!(temp_string, "Path::new({})", target_processed);
format!("Path::new({real_vars}).join(\"{str1}\")")
}
else if v[1].is_empty() {
let str1 = v[0].to_string();
format!("Path::new(\"{str1}\").join({real_vars})")
}
else {
let _ = write!(temp_string, ".join({})", target_processed);
let (str1, mut str2) = (v[0].to_string(), v[1].to_string());
if str2.starts_with('\\') || str2.starts_with('/') {
str2.remove(0);
}
format!("Path::new(\"{str1}\").join({real_vars}).join(\"{str2}\")")
}
}
};
span_lint_and_sugg(
cx,
PATH_FROM_FORMAT,
expr.span,
"`format!(..)` used to form `PathBuf`",
"consider using `.join()` to avoid the extra allocation",
temp_string,
sugg,
Applicability::MaybeIncorrect,
);
}
Expand Down
3 changes: 3 additions & 0 deletions tests/ui/path_from_format.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,4 +5,7 @@ use std::path::PathBuf;
fn main() {
let mut base_path1 = "";
PathBuf::from(format!("{}/foo/bar", base_path1));
PathBuf::from(format!("/foo/bar/{}", base_path1));
PathBuf::from(format!("/foo/{}/bar", base_path1));
PathBuf::from(format!("foo/{}/bar", base_path1));
}
22 changes: 20 additions & 2 deletions tests/ui/path_from_format.stderr
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,9 +2,27 @@ error: `format!(..)` used to form `PathBuf`
--> $DIR/path_from_format.rs:7:5
|
LL | PathBuf::from(format!("{}/foo/bar", base_path1));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `.join()` to avoid the extra allocation: `Path::new(base_path1).join("foo").join("bar")`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `.join()` to avoid the extra allocation: `Path::new(base_path1).join("foo/bar")`
|
= note: `-D clippy::path-from-format` implied by `-D warnings`

error: aborting due to previous error
error: `format!(..)` used to form `PathBuf`
--> $DIR/path_from_format.rs:8:5
|
LL | PathBuf::from(format!("/foo/bar/{}", base_path1));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `.join()` to avoid the extra allocation: `Path::new("/foo/bar/").join(base_path1)`

error: `format!(..)` used to form `PathBuf`
--> $DIR/path_from_format.rs:9:5
|
LL | PathBuf::from(format!("/foo/{}/bar", base_path1));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `.join()` to avoid the extra allocation: `Path::new("/foo/").join(base_path1).join("bar")`

error: `format!(..)` used to form `PathBuf`
--> $DIR/path_from_format.rs:10:5
|
LL | PathBuf::from(format!("foo/{}/bar", base_path1));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `.join()` to avoid the extra allocation: `Path::new("foo/").join(base_path1).join("bar")`

error: aborting due to 4 previous errors

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