Silence [question_mark] in const context

Author: kraktus

clippy_lints/src/question_mark.rs

@@ -3,8 +3,8 @@ use clippy_utils::higher;
 use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::ty::is_type_diagnostic_item;
 use clippy_utils::{
-    eq_expr_value, get_parent_node, is_else_clause, is_lang_ctor, path_to_local, path_to_local_id, peel_blocks,
-    peel_blocks_with_stmt,
+    eq_expr_value, get_parent_node, in_constant, is_else_clause, is_lang_ctor, path_to_local, path_to_local_id,
+    peel_blocks, peel_blocks_with_stmt,
 };
 use if_chain::if_chain;
 use rustc_errors::Applicability;
@@ -223,7 +223,9 @@ fn expr_return_none_or_err(
 
 impl<'tcx> LateLintPass<'tcx> for QuestionMark {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
-        check_is_none_or_err_and_early_return(cx, expr);
-        check_if_let_some_or_err_and_early_return(cx, expr);
+        if !in_constant(cx, expr.hir_id) {
+            check_is_none_or_err_and_early_return(cx, expr);
+            check_if_let_some_or_err_and_early_return(cx, expr);
+        }
     }
 }

tests/ui/question_mark.fixed

@@ -223,3 +223,12 @@ fn pattern() -> Result<(), PatternedError> {
 }
 
 fn main() {}
+
+// should not lint, `?` operator not available in const context
+const fn issue9175(option: Option<()>) -> Option<()> {
+    if option.is_none() {
+        return None;
+    }
+    //stuff
+    Some(())
+}

tests/ui/question_mark.rs

@@ -259,3 +259,12 @@ fn pattern() -> Result<(), PatternedError> {
 }
 
 fn main() {}
+
+// should not lint, `?` operator not available in const context
+const fn issue9175(option: Option<()>) -> Option<()> {
+    if option.is_none() {
+        return None;
+    }
+    //stuff
+    Some(())
+}