Command substitution starting with a (()) expression should fail

[Michael Diamond]

Configuration Information [Automatically generated, do not change]:

Machine: x86_64

OS: cygwin

Compiler: gcc

Compilation CFLAGS:  -DPROGRAM='bash.exe' -DCONF_HOSTTYPE='x86_64' -DCONF_OSTYPE='cygwin' -DCONF_MACHTYPE='x86_64-unknown-cygwin' -DCONF_VENDOR='unknown' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL -DHAVE_CONFIG_H -DRECYCLES_PIDS   -I.  -I/usr/src/bash-4.3.39-2.x86_64/src/bash-4.3 -I/usr/src/bash-4.3.39-2.x86_64/src/bash-4.3/include -I/usr/src/bash-4.3.39-2.x86_64/src/bash-4.3/lib  -DWORDEXP_OPTION -ggdb -O2 -pipe -Wimplicit-function-declaration -fdebug-prefix-map=/usr/src/bash-4.3.39-2.x86_64/build=/usr/src/debug/bash-4.3.39-2 -fdebug-prefix-map=/usr/src/bash-4.3.39-2.x86_64/src/bash-4.3=/usr/src/debug/bash-4.3.39-2

uname output: CYGWIN_NT-10.0 Aodh 2.0.4(0.287/5/3) 2015-06-09 12:22 x86_64 Cygwin

Machine Type: x86_64-unknown-cygwin

Bash Version: 4.3

Patch Level: 39

Release Status: release

Description:

I'm told $((( $exit_code == 0 )) && echo GREEN || echo RED) should fail

to parse, because $(( should be the first token, not $(.

I filed a bug https://github.com/koalaman/shellcheck/issues/590 after

running into a parser error with the ShellCheck service. They explained

the syntax I'm using *shouldn't* work, and indicated it was a bug in

Bash. I have used this syntax successfully on Cygwin, OSX, and Ubuntu.

Repeat-By:

$ exit_code=0

$ echo $((( $exit_code == 0 )) && echo GREEN || echo RED)

GREEN

$ exit_code=1

$ echo $((( $exit_code == 0 )) && echo GREEN || echo RED)

RED

Expected a parse error.