unified: "Coerce" expr to pattern

This commits demonstrates the idea we're going to use in later commits, deliberately only done for one expr type so far.

Author: asgerf

unified/extractor/src/languages/swift/swift.rs

@@ -283,6 +283,12 @@ fn translation_rules() -> Vec<Rule<SwiftContext>> {
         // can't match on token text, so a small Rust block reads the spelling
         // and routes to `compound_assign_expr` or `binary_expr`. The operator
         // is captured raw (`@@op`) to read its spelling.
+        rule!((infixOperatorExpr) @@expr where ctx.in_pattern =>
+            pattern {
+                ctx.in_pattern = false;
+                tree!((expr_equality_pattern expr: {ctx.translate(expr)?}))
+            }
+        ),
         rule!(
             (infixOperatorExpr leftOperand: @l operator: (binaryOperatorExpr) @@op rightOperand: @r)
             =>

unified/extractor/tests/corpus/swift/control-flow/switch-expression-pattern.output

@@ -291,33 +291,29 @@ top_level
                       expr:
                         name_expr
                           identifier: identifier "y"
-                    binary_expr <-- ERROR: The field or_pattern.pattern should contain pattern, but got binary_expr
-                      left:
-                        expr_equality_pattern <-- ERROR: The field binary_expr.left should contain expr, but got expr_equality_pattern
-                          expr:
+                    expr_equality_pattern
+                      expr:
+                        binary_expr
+                          left:
                             name_expr
                               identifier: identifier "y"
-                      operator: infix_operator "+"
-                      right:
-                        expr_equality_pattern <-- ERROR: The field binary_expr.right should contain expr, but got expr_equality_pattern
-                          expr: int_literal "1"
+                          operator: infix_operator "+"
+                          right: int_literal "1"
                     unary_expr <-- ERROR: The field or_pattern.pattern should contain pattern, but got unary_expr
                       operand:
                         expr_equality_pattern <-- ERROR: The field unary_expr.operand should contain expr, but got expr_equality_pattern
                           expr:
                             name_expr
                               identifier: identifier "y"
                       operator: prefix_operator "-"
-                    binary_expr <-- ERROR: The field or_pattern.pattern should contain pattern, but got binary_expr
-                      left:
-                        expr_equality_pattern <-- ERROR: The field binary_expr.left should contain expr, but got expr_equality_pattern
-                          expr:
+                    expr_equality_pattern
+                      expr:
+                        binary_expr
+                          left:
                             name_expr
                               identifier: identifier "y"
-                      operator: infix_operator "..."
-                      right:
-                        expr_equality_pattern <-- ERROR: The field binary_expr.right should contain expr, but got expr_equality_pattern
-                          expr:
+                          operator: infix_operator "..."
+                          right:
                             name_expr
                               identifier: identifier "z"
                     string_interpolation_expr <-- ERROR: The field or_pattern.pattern should contain pattern, but got string_interpolation_expr