2020-12-23 11:37:37 +00:00
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use crate::utils::paths::STRING;
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use crate::utils::{match_def_path, span_lint_and_help};
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use if_chain::if_chain;
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use lazy_static::lazy_static;
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use regex::Regex;
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use rustc_ast::ast::LitKind;
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use rustc_hir::{Expr, ExprKind, PathSegment};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::ty;
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::{source_map::Spanned, Span};
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declare_clippy_lint! {
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/// **What it does:**
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/// Checks for calls to `ends_with` with possible file extensions
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/// and suggests to use a case-insensitive approach instead.
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///
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/// **Why is this bad?**
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/// `ends_with` is case-sensitive and may not detect files with a valid extension.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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///
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/// ```rust
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/// fn is_rust_file(filename: &str) -> bool {
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/// filename.ends_with(".rs")
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/// }
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/// ```
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/// Use instead:
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/// ```rust
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/// fn is_rust_file(filename: &str) -> bool {
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/// filename.rsplit('.').next().map(|ext| ext.eq_ignore_ascii_case("rs")) == Some(true)
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/// }
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/// ```
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pub CASE_SENSITIVE_FILE_EXTENSION_COMPARISONS,
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pedantic,
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2020-12-23 15:59:17 +00:00
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"Checks for calls to ends_with with case-sensitive file extensions"
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2020-12-23 11:37:37 +00:00
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}
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declare_lint_pass!(CaseSensitiveFileExtensionComparisons => [CASE_SENSITIVE_FILE_EXTENSION_COMPARISONS]);
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fn check_case_sensitive_file_extension_comparison(ctx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Span> {
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lazy_static! {
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static ref RE: Regex = Regex::new(r"^\.([a-z0-9]{1,5}|[A-Z0-9]{1,5})$").unwrap();
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}
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if_chain! {
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if let ExprKind::MethodCall(PathSegment { ident, .. }, _, [obj, extension, ..], span) = expr.kind;
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if ident.as_str() == "ends_with";
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if let ExprKind::Lit(Spanned { node: LitKind::Str(ext_literal, ..), ..}) = extension.kind;
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if RE.is_match(&ext_literal.as_str());
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then {
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let mut ty = ctx.typeck_results().expr_ty(obj);
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ty = match ty.kind() {
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ty::Ref(_, ty, ..) => ty,
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_ => ty
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};
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match ty.kind() {
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ty::Str => {
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return Some(span);
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},
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ty::Adt(&ty::AdtDef { did, .. }, _) => {
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if match_def_path(ctx, did, &STRING) {
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return Some(span);
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}
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},
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_ => { return None; }
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}
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}
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}
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None
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}
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impl LateLintPass<'tcx> for CaseSensitiveFileExtensionComparisons {
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fn check_expr(&mut self, ctx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
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if let Some(span) = check_case_sensitive_file_extension_comparison(ctx, expr) {
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span_lint_and_help(
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ctx,
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CASE_SENSITIVE_FILE_EXTENSION_COMPARISONS,
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span,
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"case-sensitive file extension comparison",
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None,
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"consider using a case-insensitive comparison instead",
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);
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}
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}
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}
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