fix: Mark delete as prefix expression rather than a dedicated stateme…

…nt (#889)

Looking at the ethereum/solidity's code it seems it has been that way
since always; it's de facto an assignment expression with rvalue being
an initial value for the type of lvalue.

.changeset/nine-boxes-vanish.md

@@ -0,0 +1,5 @@
+---
+"@nomicfoundation/slang": patch
+---
+
+Support `delete` as an expression rather than a statement

crates/solidity/inputs/language/src/definition.rs

@@ -2787,7 +2787,6 @@ codegen_language_macros::compile!(Language(
                                 EnumVariant(reference = DoWhileStatement),
                                 EnumVariant(reference = ContinueStatement),
                                 EnumVariant(reference = BreakStatement),
-                                EnumVariant(reference = DeleteStatement),
                                 EnumVariant(reference = ReturnStatement),
                                 EnumVariant(reference = ThrowStatement, enabled = Till("0.5.0")),
                                 EnumVariant(reference = EmitStatement, enabled = From("0.4.21")),
@@ -3049,15 +3048,6 @@ codegen_language_macros::compile!(Language(
                                 arguments = Required(ArgumentsDeclaration),
                                 semicolon = Required(Semicolon)
                             )
-                        ),
-                        Struct(
-                            name = DeleteStatement,
-                            error_recovery = FieldsErrorRecovery(terminator = semicolon),
-                            fields = (
-                                delete_keyword = Required(DeleteKeyword),
-                                expression = Required(Expression),
-                                semicolon = Required(Semicolon)
-                            )
                         )
                     ]
                 ),
@@ -3371,6 +3361,10 @@ codegen_language_macros::compile!(Language(
                                             model = Prefix,
                                             enabled = Till("0.5.0"),
                                             fields = (operator = Required(Plus))
+                                        ),
+                                        PrecedenceOperator(
+                                            model = Prefix,
+                                            fields = (operator = Required(DeleteKeyword))
                                         )
                                     ]
                                 ),

crates/solidity/testing/snapshots/cst_output/Block/unchecked/generated/0.5.0-failure.yml

@@ -5,7 +5,7 @@ Source: >
 
 Errors: # 1 total
   - >
-    Error: Expected AddressKeyword or AssemblyKeyword or BoolKeyword or BreakKeyword or ByteKeyword or BytesKeyword or CloseBrace or ContinueKeyword or DecimalLiteral or DeleteKeyword or DoKeyword or DoubleQuotedHexStringLiteral or DoubleQuotedStringLiteral or EmitKeyword or FalseKeyword or FixedKeyword or ForKeyword or FunctionKeyword or HexLiteral or Identifier or IfKeyword or IntKeyword or MappingKeyword or NewKeyword or OpenBrace or OpenBracket or OpenParen or ReturnKeyword or SingleQuotedHexStringLiteral or SingleQuotedStringLiteral or StringKeyword or TrueKeyword or UfixedKeyword or UintKeyword or WhileKeyword.
+    Error: Expected AddressKeyword or AssemblyKeyword or BoolKeyword or BreakKeyword or ByteKeyword or BytesKeyword or CloseBrace or ContinueKeyword or DecimalLiteral or DoKeyword or DoubleQuotedHexStringLiteral or DoubleQuotedStringLiteral or EmitKeyword or FalseKeyword or FixedKeyword or ForKeyword or FunctionKeyword or HexLiteral or Identifier or IfKeyword or IntKeyword or MappingKeyword or NewKeyword or OpenBrace or OpenBracket or OpenParen or ReturnKeyword or SingleQuotedHexStringLiteral or SingleQuotedStringLiteral or StringKeyword or TrueKeyword or UfixedKeyword or UintKeyword or WhileKeyword.
        ╭─[crates/solidity/testing/snapshots/cst_output/Block/unchecked/input.sol:1:3]
        │
      1 │ { unchecked { x = 1; } }