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ned14 / pcpp

A C99 preprocessor written in pure Python
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exception: couldn't evaluate expression due to Traceback #48

Closed schra closed 3 years ago

schra commented 3 years ago

The lines at https://github.com/bminor/glibc/blob/glibc-2.32/include/features.h#L432-L439 throw an exception:

$ wget https://raw.githubusercontent.com/bminor/glibc/glibc-2.32/include/features.h
$ pcpp --passthru-unfound-includes features.h
features.h:432 warning: couldn't evaluate expression due to Traceback (most recent call last):
  File "/usr/lib/python3.8/site-packages/pcpp/preprocessor.py", line 1161, in evalexpr
    result = int(eval(expr, evalfuncts, evalvars))
  File "<string>", line 1
    (0                                and  (0 < 201103  and   not 0)      if  (0                              else  ( not 0  or  0 < 199901)))
                                                                                                              ^
SyntaxError: invalid syntax

Converted expression was (0                               and  (0 < 201103  and   not 0)      if  (0                              else  ( not 0  or  0 < 199901))) with evalvars = {}
#line 443 "features.h"
#include <stdc-predef.h>
#line 465 "features.h"
#  include <sys/cdefs.h>
#line 489 "features.h"
#include <gnu/stubs.h>

I'll get even more of the same exception when the includes are actually resolved:

$ pcpp -I/usr/include /usr/include/features.h
../features.h:432 warning: couldn't evaluate expression due to Traceback (most recent call last):
  File "/usr/lib/python3.8/site-packages/pcpp/preprocessor.py", line 1161, in evalexpr
    result = int(eval(expr, evalfuncts, evalvars))
  File "<string>", line 1
    (0                                and  (0 < 201103  and   not 0)      if  (0                              else  ( not 0  or  0 < 199901)))
                                                                                                              ^
SyntaxError: invalid syntax

Converted expression was (0                               and  (0 < 201103  and   not 0)      if  (0                              else  ( not 0  or  0 < 199901))) with evalvars = {}
../sys/cdefs.h:415 warning: couldn't evaluate expression due to Traceback (most recent call last):
  File "/usr/lib/python3.8/site-packages/pcpp/preprocessor.py", line 1161, in evalexpr
    result = int(eval(expr, evalfuncts, evalvars))
  File "<string>", line 1
    ( not 0       and  0  if  (0  else  0) < 201112       and    not 0)
                                  ^
SyntaxError: invalid syntax

Converted expression was ( not 0       and  0  if  (0  else  0) < 201112       and    not 0) with evalvars = {}
../sys/cdefs.h:444 warning: couldn't evaluate expression due to Traceback (most recent call last):
  File "/usr/lib/python3.8/site-packages/pcpp/preprocessor.py", line 1161, in evalexpr
    result = int(eval(expr, evalfuncts, evalvars))
  File "<string>", line 1
    ( not 0  and   not 0       and  0  if  (0  else  0) < 201112       and  ( not 0  or  0))
                                               ^
SyntaxError: invalid syntax

Converted expression was ( not 0  and   not 0       and  0  if  (0  else  0) < 201112       and  ( not 0  or  0)) with evalvars = {}

I'm using pcpp 1.22

ned14 commented 3 years ago

As described in the Readme, the expression evaluator in pcpp is based on a lossy conversion to a Python expression, and for complex expressions this breaks down.

ned14 commented 3 years ago

Fixed! Thanks for the BR.