Add tests of bailout involving ranges and dots, and fix for question

dtolnay · Dec 30, 2024 · 6b88946 · 6b88946
1 parent ed4d144
commit 6b88946
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Showing 2 changed files with 78 additions and 1 deletion.
diff --git a/src/expr.rs b/src/expr.rs
@@ -1673,7 +1673,12 @@ pub(crate) mod parsing {
                     bracket_token: bracketed!(content in input),
                     index: content.parse()?,
                 });
-            } else if input.peek(Token![?]) {
+            } else if input.peek(Token![?])
+                && match e {
+                    Expr::Range(_) => false,
+                    _ => true,
+                }
+            {
                 e = Expr::Try(ExprTry {
                     attrs: Vec::new(),
                     expr: Box::new(e),
@@ -2867,6 +2872,7 @@ pub(crate) mod parsing {
                 || input.peek(Token![,])
                 || input.peek(Token![;])
                 || input.peek(Token![.]) && !input.peek(Token![..])
+                || input.peek(Token![?])
                 || input.peek(Token![=>])
                 || !allow_struct.0 && input.peek(token::Brace))
         {

diff --git a/tests/test_expr.rs b/tests/test_expr.rs
@@ -407,6 +407,77 @@ fn test_range_precedence() {
     syn::parse_str::<Expr>("x .. x ..").unwrap_err();
 }
 
+#[test]
+fn test_ranges_dots_bailout() {
+    syn::parse_str::<Expr>(".. ?").unwrap_err();
+    syn::parse_str::<Expr>(".. .field").unwrap_err();
+
+    snapshot!("return .. ?" as Expr, @r"
+    Expr::Try {
+        expr: Expr::Return {
+            expr: Some(Expr::Range {
+                limits: RangeLimits::HalfOpen,
+            }),
+        },
+    }
+    ");
+
+    snapshot!("break .. ?" as Expr, @r"
+    Expr::Try {
+        expr: Expr::Break {
+            expr: Some(Expr::Range {
+                limits: RangeLimits::HalfOpen,
+            }),
+        },
+    }
+    ");
+
+    snapshot!("|| .. ?" as Expr, @r"
+    Expr::Try {
+        expr: Expr::Closure {
+            output: ReturnType::Default,
+            body: Expr::Range {
+                limits: RangeLimits::HalfOpen,
+            },
+        },
+    }
+    ");
+
+    snapshot!("return .. .field" as Expr, @r#"
+    Expr::Field {
+        base: Expr::Return {
+            expr: Some(Expr::Range {
+                limits: RangeLimits::HalfOpen,
+            }),
+        },
+        member: Member::Named("field"),
+    }
+    "#);
+
+    snapshot!("break .. .field" as Expr, @r#"
+    Expr::Field {
+        base: Expr::Break {
+            expr: Some(Expr::Range {
+                limits: RangeLimits::HalfOpen,
+            }),
+        },
+        member: Member::Named("field"),
+    }
+    "#);
+
+    snapshot!("|| .. .field" as Expr, @r#"
+    Expr::Field {
+        base: Expr::Closure {
+            output: ReturnType::Default,
+            body: Expr::Range {
+                limits: RangeLimits::HalfOpen,
+            },
+        },
+        member: Member::Named("field"),
+    }
+    "#);
+}
+
 #[test]
 fn test_ambiguous_label() {
     for stmt in [