modify code

[rust.git] / clippy_lints / src / strlen_on_c_strings.rs

diff --git a/clippy_lints/src/strlen_on_c_strings.rs b/clippy_lints/src/strlen_on_c_strings.rs
index be7431f11aad04af75a906aeb92c6a931caf3af9..7bc9cf742e6549e7dbbcffa91b499da3766d61bb 100644 (file)
--- a/clippy_lints/src/strlen_on_c_strings.rs
+++ b/clippy_lints/src/strlen_on_c_strings.rs
@@ -1,13 +1,14 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
-use clippy_utils::paths;
-use clippy_utils::source::snippet_with_macro_callsite;
-use clippy_utils::ty::{is_type_diagnostic_item, is_type_ref_to_diagnostic_item};
+use clippy_utils::source::snippet_with_context;
+use clippy_utils::ty::is_type_diagnostic_item;
+use clippy_utils::visitors::is_expr_unsafe;
+use clippy_utils::{get_parent_node, match_libc_symbol};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
-use rustc_hir as hir;
+use rustc_hir::{Block, BlockCheckMode, Expr, ExprKind, Node, UnsafeSource};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::symbol::{sym, Symbol};
+use rustc_span::symbol::sym;
 
 declare_clippy_lint! {
     /// ### What it does
@@ -38,30 +39,36 @@
 
 declare_lint_pass!(StrlenOnCStrings => [STRLEN_ON_C_STRINGS]);
 
-impl LateLintPass<'tcx> for StrlenOnCStrings {
-    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
-        if expr.span.from_expansion() {
-            return;
-        }
-
+impl<'tcx> LateLintPass<'tcx> for StrlenOnCStrings {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         if_chain! {
-            if let hir::ExprKind::Call(func, [recv]) = expr.kind;
-            if let hir::ExprKind::Path(hir::QPath::Resolved(_, path)) = func.kind;
-
-            if (&paths::LIBC_STRLEN).iter().map(|x| Symbol::intern(x)).eq(
-                path.segments.iter().map(|seg| seg.ident.name));
-            if let hir::ExprKind::MethodCall(path, _, args, _) = recv.kind;
-            if args.len() == 1;
-            if !args.iter().any(|e| e.span.from_expansion());
+            if !expr.span.from_expansion();
+            if let ExprKind::Call(func, [recv]) = expr.kind;
+            if let ExprKind::Path(path) = &func.kind;
+            if let Some(did) = cx.qpath_res(path, func.hir_id).opt_def_id();
+            if match_libc_symbol(cx, did, "strlen");
+            if let ExprKind::MethodCall(path, [self_arg], _) = recv.kind;
+            if !recv.span.from_expansion();
             if path.ident.name == sym::as_ptr;
             then {
-                let cstring = &args[0];
-                let ty = cx.typeck_results().expr_ty(cstring);
-                let val_name = snippet_with_macro_callsite(cx, cstring.span, "..");
-                let sugg = if is_type_diagnostic_item(cx, ty, sym::cstring_type){
-                    format!("{}.as_bytes().len()", val_name)
-                } else if is_type_ref_to_diagnostic_item(cx, ty, sym::CStr){
-                    format!("{}.to_bytes().len()", val_name)
+                let ctxt = expr.span.ctxt();
+                let span = match get_parent_node(cx.tcx, expr.hir_id) {
+                    Some(Node::Block(&Block {
+                        rules: BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided), span, ..
+                    }))
+                    if span.ctxt() == ctxt && !is_expr_unsafe(cx, self_arg) => {
+                        span
+                    }
+                    _ => expr.span,
+                };
+
+                let ty = cx.typeck_results().expr_ty(self_arg).peel_refs();
+                let mut app = Applicability::MachineApplicable;
+                let val_name = snippet_with_context(cx, self_arg.span, ctxt, "..", &mut app).0;
+                let method_name = if is_type_diagnostic_item(cx, ty, sym::cstring_type) {
+                    "as_bytes"
+                } else if is_type_diagnostic_item(cx, ty, sym::CStr) {
+                    "to_bytes"
                 } else {
                     return;
                 };
@@ -69,11 +76,11 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
                 span_lint_and_sugg(
                     cx,
                     STRLEN_ON_C_STRINGS,
-                    expr.span,
+                    span,
                     "using `libc::strlen` on a `CString` or `CStr` value",
-                    "try this (you might also need to get rid of `unsafe` block in some cases):",
-                    sugg,
-                    Applicability::Unspecified // Sometimes unnecessary `unsafe` block
+                    "try this",
+                    format!("{}.{}().len()", val_name, method_name),
+                    app,
                 );
             }
         }