* Be less strict about multi-line preprocessor directives (e.g. those
with comments hanging off the right-hand end) since they're more
of a problem in practise than I expected. Prompted by phk.
* Fix the handling of "ignore" symbols.
* Style pedantry from OpenBSD and Ted Unangst <tedu@stanford.edu>,
including some whitespace fixes and removal of strcpy()
(and not including excessively strict KNF enforcement).
* Fix some typos and terminological inconsistencies.
* The partial-evaluation of #elif sequences was broken and the
spaghetti logic of its implementation was too hard to understand.
I've re-done it using a straight-forward table-driven push-down
automaton.
* The pre-processor line parser did not allow for all of the weird
places that people might put comments, which could have caused it
to add syntax-errors to the output by removing a #if line containing
the start- or end-marker of a comment.
* The lexer didn't need to special-case the handling of string-literals
or character-constants, but it did need to learn about line-continuations
(backslash-newline).
* The input routine was buggy and bit-rotten and trivially replacable
with fgets(). I've also made the program static- and const-safe and
improved the presentation-order. The formatting of the state-transition
tables remains non-stylish.
This commit-messsage was brought to you by code-point 45.
MFC-after: one-week
constant controlling expressions: in particular, removing #if 0 sections
is considered "rude". This commit changes the default so that such
things are passed through unchanged, and the old behaviour can be had
with the -k "kill konsts" flag.
Suggested by: markm
MFC after: 3 weeks
* Ensure we work within the array bounds when parsing command-line options;
* Replace h0h0getopt with getopt(3);
* Use consistent whitespace style in the function declarations.
Revieweded by: dwmalone (mentor)
* It now knows about the existence of #elif which would have
caused it to produce incorrect results in some situations.
* It can now process #if and #elif lines according to the
values of symbols that are specified on the command line.
The expression parser is only a simple subset of what C
allows but it should be sufficient for most real-world
code (it can cope with everything it finds in xterm).
* It has an option for printing all of the symbols that might
control #if processing. The unifdefall script uses this
option along with cpp -dM to strip all #ifs from a file.
* It has much larger static limits.
* It handles nested #ifs much more completely.
There have also been many style improvements: KNF; ANSI function
definitions; all global stuff moved to the top of the file; use
stdbool instead of h0h0bool; const-correctness; err(3) instead
of fprintf(stderr, ...); enum instead of #define; commentary.
I used NetBSD's unifdef as the basis of this since it has received
the most attention over the years.
PR: 37454
Reviewed by: markm, dwmalone
Approved by: dwmalone (mentor)
MFC after: 3 weeks
