fparser2: program statement with missing name causes crash

[arporter]

According to R1102 the PROGRAM statement must have an associated name. However, if fparser2 encounters e.g.

program
  write(*,*) "Hello"
end program

then it crashes with:

    @staticmethod
    def match(string):
>       return StringBase.match(pattern.abs_name, string.replace(' ', ''))
E       AttributeError: 'NoneType' object has no attribute 'replace'

fparser/src/fparser/two/Fortran2003.py:559: AttributeError

It should of course raise a SyntaxError.

[rupertford]

R1102 simply makes use of BlockBase to do its match. It turns out that blockbase does not check whether the name for the startclass has been supplied before comparing. If we add the following code

            if hasattr(obj, 'get_name'):
                if not obj.get_name():
                    obj.restore_reader(reader)
                    raise FortranSyntaxError("Name is required")

after the existing code

            if match_names:
                start_name = obj.get_start_name()

we raise the exception.

Hwever, why does the name matching return an error?

[rupertford]

Actually it can (and I think should) be intercepted in the Program_Stmt class. This class currently happily returns a null or empty "" name. However we want to raise an exception if this is the case. The following code does this. I think we need #121 to be on master first though.

    def match(string):
        result = WORDClsBase.match('PROGRAM', Program_Name, string,
                                 require_cls=True)
        if not result[1]:
            raise FortranSyntaxError("There be no name my lover")
        return result
    match = staticmethod(match)

[rupertford]

OK, I've changed my mind again. WORDClsBase is used in many situations in fparser2. Whenever its match() method is used with require_cls=True the associated rule expects to have content for the class instance. Therefore an exception should be raised in all of these cases. The reason one is not raised is because the implementation of WORDClsBase returns a match but with None as the return value for the class instance. This is a simple bug, the code that does this test appears after the optional "::" is dealt with so anything without "::" misses the test.

For example

program  xx 
! R521 says the object name list must not be empty
asynchronous
! R537 says the dummy arg name list must not be empty
optional
! R540 says the pointer declaration list must not be empty
pointer
end program
rupert@ubuntu:~/proj/fparser/src/fparser$ ./scripts/fparser2.py test.f90
PROGRAM xx
  ASYNCHRONOUS
  OPTIONAL
  POINTER
END PROGRAM xx
rupert@ubuntu:~/proj/fparser/src/fparser$

Syntax errors should be raised for each of the three lines but are not. All of these examples use WORDClsBase. If we modify the match method appropriately, we get the expected result ...

rupert@ubuntu:~/proj/fparser/src/fparser$ ./scripts/fparser2.py test.f90
Syntax error: at line 3
>>>asynchronous

[arporter]

123 has been merged to master.