Thread: [ecpg bug]: can not use single '*' in multi-line comment after c preprocessor directives
[ecpg bug]: can not use single '*' in multi-line comment after c preprocessor directives
From
"Winter Loo"
Date:
Hi hackers,
The following code fails to pass the ecpg compilation, although it is accepted by the gcc compiler.
```
#if ABC /* this is a multi-line
* comment including single star character */
int a = 1;
#endif
```
The issue arises from the first '*' in the second line. Upon its removal, the ecpg compiler functions properly.
```
#if ABC /* this is a multi-line
comment without single star character */
int a = 1;
#endif
```
The problem has been identified as a bug in the `cppline` definition within the `pgc.l` file.
```
cppline {space}*#([^i][A-Za-z]*|{if}|{ifdef}|{ifndef}|{import})((\/\*[^*/]*\*+\/)|.|\\{space}*{newline})*{newline}
```
[Source](https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/interfaces/ecpg/preproc/pgc.l;h=f3c03482aec61956691f30426f61510920c5c702;hb=HEAD#l461)
More specifically, the bug originates from the regex pattern for the C block code comment.
```
\/\*[^*/]*\*+\/
```
Attempting another example:
```
#if ABC /* hello * world */
int a = 1;
#endif
```
This time, the ecpg compiler also functions correctly.
Confused! I am uncertain how to rectify the regex. I hope someone can address this bug.
Re: [ecpg bug]: can not use single '*' in multi-line comment after c preprocessor directives
From
Tom Lane
Date:
"Winter Loo" <winterloo@126.com> writes:
> The following code fails to pass the ecpg compilation, although it is accepted by the gcc compiler.
Yeah ... an isolated "/" inside the comment doesn't work either.
> Confused! I am uncertain how to rectify the regex. I hope someone can address this bug.
I poked at this for awhile and concluded that we probably cannot make
it work with a single regexp for "cppline". The right thing would
involve an exclusive start condition for parsing a cppline, more or
less like the way that /* comments are parsed in the <xc> start
condition. This is kind of a lot of work compared to the value :-(.
Maybe somebody else would like to take a crack at it, but I can't
get excited enough about it.
There are other deficiencies too in ecpg's handling of these things,
like the fact that (I think) comments are mishandled in #include
directives.
regards, tom lane