Auto merge of #4544 - JoshMcguigan:issue-4542, r=flip1995

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

diff --git a/clippy_lints/src/types.rs b/clippy_lints/src/types.rs
index 3c2111c55fb56e9bc9c05be6a8722bac07f7c4fd..5696c2be12a8c6bb801d249f68509d48a3794108 100644 (file)
--- a/clippy_lints/src/types.rs
+++ b/clippy_lints/src/types.rs
@@ -15,16 +15,16 @@
 use rustc_errors::Applicability;
 use rustc_target::spec::abi::Abi;
 use rustc_typeck::hir_ty_to_ty;
-use syntax::ast::{FloatTy, IntTy, UintTy};
+use syntax::ast::{FloatTy, IntTy, LitIntType, LitKind, UintTy};
 use syntax::errors::DiagnosticBuilder;
 use syntax::source_map::Span;
-use syntax::symbol::sym;
+use syntax::symbol::{sym, Symbol};
 
 use crate::consts::{constant, Constant};
 use crate::utils::paths;
 use crate::utils::{
     clip, comparisons, differing_macro_contexts, higher, in_constant, int_bits, last_path_segment, match_def_path,
-    match_path, multispan_sugg, same_tys, sext, snippet, snippet_opt, snippet_with_applicability,
+    match_path, multispan_sugg, qpath_res, same_tys, sext, snippet, snippet_opt, snippet_with_applicability,
     snippet_with_macro_callsite, span_help_and_lint, span_lint, span_lint_and_sugg, span_lint_and_then, unsext,
 };
 
@@ -218,7 +218,7 @@ fn match_type_parameter(cx: &LateContext<'_, '_>, qpath: &QPath, path: &[&str])
             _ => None,
         });
         if let TyKind::Path(ref qpath) = ty.node;
-        if let Some(did) = cx.tables.qpath_res(qpath, ty.hir_id).opt_def_id();
+        if let Some(did) = qpath_res(cx, qpath, ty.hir_id).opt_def_id();
         if match_def_path(cx, did, path);
         then {
             return true;
@@ -240,7 +240,7 @@ fn check_ty(cx: &LateContext<'_, '_>, hir_ty: &hir::Ty, is_local: bool) {
     match hir_ty.node {
         TyKind::Path(ref qpath) if !is_local => {
             let hir_id = hir_ty.hir_id;
-            let res = cx.tables.qpath_res(qpath, hir_id);
+            let res = qpath_res(cx, qpath, hir_id);
             if let Some(def_id) = res.opt_def_id() {
                 if Some(def_id) == cx.tcx.lang_items().owned_box() {
                     if match_type_parameter(cx, qpath, &paths::VEC) {
@@ -253,7 +253,7 @@ fn check_ty(cx: &LateContext<'_, '_>, hir_ty: &hir::Ty, is_local: bool) {
                         );
                         return; // don't recurse into the type
                     }
-                } else if match_def_path(cx, def_id, &paths::VEC) {
+                } else if cx.tcx.is_diagnostic_item(Symbol::intern("vec_type"), def_id) {
                     if_chain! {
                         // Get the _ part of Vec<_>
                         if let Some(ref last) = last_path_segment(qpath).args;
@@ -263,7 +263,7 @@ fn check_ty(cx: &LateContext<'_, '_>, hir_ty: &hir::Ty, is_local: bool) {
                         });
                         // ty is now _ at this point
                         if let TyKind::Path(ref ty_qpath) = ty.node;
-                        let res = cx.tables.qpath_res(ty_qpath, ty.hir_id);
+                        let res = qpath_res(cx, ty_qpath, ty.hir_id);
                         if let Some(def_id) = res.opt_def_id();
                         if Some(def_id) == cx.tcx.lang_items().owned_box();
                         // At this point, we know ty is Box<T>, now get T
@@ -369,7 +369,7 @@ fn check_ty_rptr(cx: &LateContext<'_, '_>, hir_ty: &hir::Ty, is_local: bool, lt:
     match mut_ty.ty.node {
         TyKind::Path(ref qpath) => {
             let hir_id = mut_ty.ty.hir_id;
-            let def = cx.tables.qpath_res(qpath, hir_id);
+            let def = qpath_res(cx, qpath, hir_id);
             if_chain! {
                 if let Some(def_id) = def.opt_def_id();
                 if Some(def_id) == cx.tcx.lang_items().owned_box();
@@ -765,7 +765,7 @@ fn is_unit_literal(expr: &Expr) -> bool {
     /// }
     /// ```
     pub CAST_LOSSLESS,
-    complexity,
+    pedantic,
     "casts using `as` that are known to be lossless, e.g., `x as u64` where `x: u8`"
 }
 
@@ -1122,7 +1122,6 @@ fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
             let (cast_from, cast_to) = (cx.tables.expr_ty(ex), cx.tables.expr_ty(expr));
             lint_fn_to_numeric_cast(cx, expr, ex, cast_from, cast_to);
             if let ExprKind::Lit(ref lit) = ex.node {
-                use syntax::ast::{LitIntType, LitKind};
                 if let LitKind::Int(n, _) = lit.node {
                     if cast_to.is_floating_point() {
                         let from_nbits = 128 - n.leading_zeros();
@@ -1487,29 +1486,40 @@ fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
     /// ```
     pub CHAR_LIT_AS_U8,
     complexity,
-    "casting a character literal to u8"
+    "casting a character literal to u8 truncates"
 }
 
 declare_lint_pass!(CharLitAsU8 => [CHAR_LIT_AS_U8]);
 
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for CharLitAsU8 {
     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
-        use syntax::ast::LitKind;
-
-        if let ExprKind::Cast(ref e, _) = expr.node {
-            if let ExprKind::Lit(ref l) = e.node {
-                if let LitKind::Char(_) = l.node {
-                    if ty::Uint(UintTy::U8) == cx.tables.expr_ty(expr).sty && !expr.span.from_expansion() {
-                        let msg = "casting character literal to u8. `char`s \
-                                   are 4 bytes wide in rust, so casting to u8 \
-                                   truncates them";
-                        let help = format!(
-                            "Consider using a byte literal instead:\nb{}",
-                            snippet(cx, e.span, "'x'")
-                        );
-                        span_help_and_lint(cx, CHAR_LIT_AS_U8, expr.span, msg, &help);
-                    }
-                }
+        if_chain! {
+            if !expr.span.from_expansion();
+            if let ExprKind::Cast(e, _) = &expr.node;
+            if let ExprKind::Lit(l) = &e.node;
+            if let LitKind::Char(c) = l.node;
+            if ty::Uint(UintTy::U8) == cx.tables.expr_ty(expr).sty;
+            then {
+                let mut applicability = Applicability::MachineApplicable;
+                let snippet = snippet_with_applicability(cx, e.span, "'x'", &mut applicability);
+
+                span_lint_and_then(
+                    cx,
+                    CHAR_LIT_AS_U8,
+                    expr.span,
+                    "casting a character literal to `u8` truncates",
+                    |db| {
+                        db.note("`char` is four bytes wide, but `u8` is a single byte");
+
+                        if c.is_ascii() {
+                            db.span_suggestion(
+                                expr.span,
+                                "use a byte literal instead",
+                                format!("b{}", snippet),
+                                applicability,
+                            );
+                        }
+                });
             }
         }
     }