Merge tag 'debian/1.52.1+dfsg1-1_exp2' into proxmox/buster

[rustc.git] / src / tools / clippy / clippy_lints / src / transmute / transmute_int_to_char.rs

diff --git a/src/tools/clippy/clippy_lints/src/transmute/transmute_int_to_char.rs b/src/tools/clippy/clippy_lints/src/transmute/transmute_int_to_char.rs
new file mode 100644 (file)
index 0000000..29d2450
--- /dev/null
+++ b/src/tools/clippy/clippy_lints/src/transmute/transmute_int_to_char.rs
@@ -0,0 +1,44 @@
+use super::TRANSMUTE_INT_TO_CHAR;
+use crate::utils::{span_lint_and_then, sugg};
+use rustc_ast as ast;
+use rustc_errors::Applicability;
+use rustc_hir::Expr;
+use rustc_lint::LateContext;
+use rustc_middle::ty::{self, Ty};
+
+/// Checks for `transmute_int_to_char` lint.
+/// Returns `true` if it's triggered, otherwise returns `false`.
+pub(super) fn check<'tcx>(
+    cx: &LateContext<'tcx>,
+    e: &'tcx Expr<'_>,
+    from_ty: Ty<'tcx>,
+    to_ty: Ty<'tcx>,
+    args: &'tcx [Expr<'_>],
+) -> bool {
+    match (&from_ty.kind(), &to_ty.kind()) {
+        (ty::Int(ty::IntTy::I32) | ty::Uint(ty::UintTy::U32), &ty::Char) => {
+            span_lint_and_then(
+                cx,
+                TRANSMUTE_INT_TO_CHAR,
+                e.span,
+                &format!("transmute from a `{}` to a `char`", from_ty),
+                |diag| {
+                    let arg = sugg::Sugg::hir(cx, &args[0], "..");
+                    let arg = if let ty::Int(_) = from_ty.kind() {
+                        arg.as_ty(ast::UintTy::U32.name_str())
+                    } else {
+                        arg
+                    };
+                    diag.span_suggestion(
+                        e.span,
+                        "consider using",
+                        format!("std::char::from_u32({}).unwrap()", arg.to_string()),
+                        Applicability::Unspecified,
+                    );
+                },
+            );
+            true
+        },
+        _ => false,
+    }
+}