bug in the sage preparser -- vector(v)[3] = 5 slips by!

[williamstein]

The Sage preparser stupidly doesn't raise an error when the input is vector(v)[3] = 5. Instead
it does something very confusing. This was found by Franco Saliola.

sage: vector(v)[3] = 5
sage: preparse('vector(v)[3] = 5')
'_=var("v");vector=symbolic_expression(Integer(5)).function(v)'
sage: vector(10)
5

CC: @robertwb @boothby

Component: misc

Issue created by migration from https://trac.sagemath.org/ticket/3846

[williamstein]

comment:1

Here's another funny example:

sage: foo(x,y)hithere fred wuz up?!  how is going = x+y
sage: foo(2,3)
5

[sagetrac-mabshoff]

comment:2

I can no longer reproduce this example in Sage 3.3.rc0. Can someone decide what needs to happen with this bug?

Cheers,

Michael

[mwhansen]

comment:3

This looks fixed to me in 4.0.1:

----------------------------------------------------------------------
| Sage Version 4.0.1.rc1, Release Date: 2009-06-04                   |
| Type notebook() for the GUI, and license() for information.        |
----------------------------------------------------------------------
sage: 'vector(v)[Integer(3)] = Integer(5)'
'vector(v)[Integer(3)] = Integer(5)'
sage: sage: foo(x,y)hithere fred wuz up?!  how is going = x+y
------------------------------------------------------------
   File "<ipython console>", line 1
     foo(x,y)hithere fred wuz up?!  how is going = x+y
                   ^
SyntaxError: invalid syntax