[Bug c++/68450] New: regex matching different from ECMAScript?

[lcoquelle at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68450

Bug ID: 68450
   Summary: regex matching different from ECMAScript?
   Product: gcc
   Version: 4.9.2
Status: UNCONFIRMED
  Severity: minor
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: lcoquelle at gmail dot com
  Target Milestone: ---

Created attachment 36777
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36777&action=edit
Code sample

Using a complex regex to remove comment in JSON file (...), the behaviour seems
to differ from ECMAScript.
FYI: boost::regex 1.59 seems to have the correct behaviour.

Regex: ((['"])(?:(?!\2|\\).|\\.)*\2)|\/\/[^\n]*|\/\*(?:[^*]|\*(?!\/))*\*\/
(can be try here: https://regex101.com/r/vI2iW5/2#javascript)

Input string: "Entry": "Value", // Skip "me"
Expected output: "Entry": "Value", 
Real output: "Entry": "Value", // Skip "me"



Attached a code sample.
Compiling output as below:


> /usr/local/gcc49/bin/g++ -v -save-temps -Wall -std=gnu++14 re.cc 
Using built-in specs.
COLLECT_GCC=/usr/local/gcc49/bin/g++
COLLECT_LTO_WRAPPER=/usr/local/gcc49/libexec/gcc/x86_64-unknown-linux-gnu/4.9.2/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: /usr/local/src/gcc-4.9.2/configure --disable-multilib
--enable-cloog-backend=isl --enable-gold=default --enable-languages=c,c++
--enable-lto --enable-libssp --enable-plugins --enable-plugin
--with-build-config=bootstrap-lto --enable-stage1-checking=release
--prefix=/usr/local/gcc49
Thread model: posix
gcc version 4.9.2 (GCC) 
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-std=gnu++1y' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'
 /usr/local/gcc49/libexec/gcc/x86_64-unknown-linux-gnu/4.9.2/cc1plus -E -quiet
-v -D_GNU_SOURCE re.cc -mtune=generic -march=x86-64 -std=gnu++1y -Wall
-fpch-preprocess -o re.ii
ignoring nonexistent directory
"/usr/local/gcc49/lib/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../x86_64-unknown-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:

/usr/local/gcc49/lib/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2

/usr/local/gcc49/lib/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/x86_64-unknown-linux-gnu

/usr/local/gcc49/lib/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/backward
 /usr/local/gcc49/lib/gcc/x86_64-unknown-linux-gnu/4.9.2/include
 /usr/local/include
 /usr/local/gcc49/include
 /usr/local/gcc49/lib/gcc/x86_64-unknown-linux-gnu/4.9.2/include-fixed
 /usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-std=gnu++1y' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'
 /usr/local/gcc49/libexec/gcc/x86_64-unknown-linux-gnu/4.9.2/cc1plus
-fpreprocessed re.ii -quiet -dumpbase re.cc -mtune=generic -march=x86-64
-auxbase re -Wall -std=gnu++1y -version -o re.s
GNU C++ (GCC) version 4.9.2 (x86_64-unknown-linux-gnu)
compiled by GNU C version 4.9.2, GMP version 6.0.0, MPFR version 3.1.2,
MPC version 1.0.2
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++ (GCC) version 4.9.2 (x86_64-unknown-linux-gnu)
compiled by GNU C version 4.9.2, GMP version 6.0.0, MPFR version 3.1.2,
MPC version 1.0.2
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 4c9e457b752b2d9171dda4de0a18535a
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-std=gnu++1y' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'

/usr/local/gcc49/lib/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../x86_64-unknown-linux-gnu/bin/as
-v --64 -o re.o re.s
GNU assembler version 2.24 (x86_64-unknown-linux-gnu) using BFD version (GNU
Binutils) 2.24
COMPILER_PATH=/usr/local/gcc49/libexec/gcc/x86_64-unknown-linux-gnu/4.9.2/:/usr/local/gcc49/libexec/gcc/x86_64-unknown-linux-gnu/4.9.2/:/usr/local/gcc49/libexec/gcc/x86_64-unknown-linux-gnu/:/usr/local/gcc49/lib/gcc/x86_64-unknown-linux-gnu/4.9.2/:/usr/local/gcc49/lib/gcc/x86_64-unknown-linux-gnu/:/usr/local/gcc49/lib/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../x86_64-unknown-linux-gnu/bin/
LIBRARY_PATH=/usr/local/gcc49/lib/gcc/x86_64-unknown-linux-gnu/4.9.2/:/usr/local/gcc49/lib/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../lib64/:/lib/../lib64/:/usr/lib/../lib64/:/usr/local/gcc49/lib/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../x86_64-unknown-linux-gnu/lib/:/usr/local/gcc49/lib/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-std=gnu++1y' '-shared-libgcc'
'-mtune=

[Bug libstdc++/68450] regex matching different from ECMAScript?

[lcoquelle at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68450

--- Comment #2 from Ludo  ---
(In reply to Tim Shen from comment #1)
> I think I unintentionally fixed this problem in my refactoring branch:
> https://github.com/innocentim/gcc/commits/master
> 
> I ran this branch and get the result:
> "Field": "Value"  
> "Field": "Value"  
> 
> Each line has two trailing spaces, which is the same as my boost output.
> 
> I'm not sure when this branch may get reviewed checked in (it involves a lot
> of changes), but I personally hope it's before the next big release.
> 
> Alternatively I can find the commit that fixes this issue, cherry pick it to
> the trunk, and rebase my branch; but I know that rebasing is gonna be super
> painful, so I'd rather wait for a while.

Nice! thanks for looking at it!