Statements

If a statement represents a context in which an expression is required to yield a specific type, Expression.Required must be set to that type. Computation provided by the type analysis modules will then report an error if the actual type is not acceptable as the required type.

Statements[42]:

RULE: Statement ::=
        'if' '(' Expression ')' Statement 'else' Statement COMPUTE
  Expression.Required=boolType;
END;

RULE: Statement ::= 'if' '(' Expression ')' Statement COMPUTE
  Expression.Required=boolType;
END;

RULE: WhileStatement ::= 'while' '(' Expression ')' Statement COMPUTE
  Expression.Required=boolType;
END;

RULE: DoStatement ::= 'do' Statement 'while' '(' Expression ')' ';' COMPUTE
  Expression.Required=boolType;
END;

RULE: ForTest ::= Expression COMPUTE
  Expression.Required=boolType;
END;

RULE: Statement ::= 'throw' Expression ';' COMPUTE
  Expression.Required=throwableType;
END;

This macro is defined in definitions 42 and 43.
This macro is invoked in definition 2.

The expression of a return statement must return a value compatible with the method containing the return statement. This requires an extra attribute at the appropriate point to specify that type. Constructors and class initializers cannot return values, so the void type is specified in those cases. Since no other type is acceptable as the void type, this will result in an error report if a return statement with an expression is used in a constructor or class initializer.

Statements[43]:

ATTR ReturnType: DefTableKey;

RULE: Statement ::= 'return' Expression ';' COMPUTE
  Expression.Required=
    INCLUDING (MethodBody.ReturnType,
               ConstructorDeclaration.ReturnType,
               ClassInitializer.ReturnType);
END;

RULE: MethodDeclarator ::= MethodIdDef '(' FormalParameters ')' COMPUTE
  MethodIdDef.ReturnType=MethodDeclarator.Type;
END;

RULE: MethodDeclaration ::= MethodHeader MethodBody COMPUTE
  MethodBody.ReturnType=MethodHeader CONSTITUENT MethodIdDef.ReturnType;
END;

SYMBOL ConstructorDeclaration COMPUTE
  SYNT.ReturnType=voidType;
END;

SYMBOL ClassInitializer COMPUTE
  SYNT.ReturnType=voidType;
END;

This macro is defined in definitions 42 and 43.
This macro is invoked in definition 2.

The convoluted mechanism for obtaining the method return type is again due to the obsolete construct discussed in Section 5.2.3.