When expanding command substitutions, we use a naïve way of detecting whether
the cmdsub has the optional leading dollar. We check if the last character was
a dollar, which breaks if it's an escaped dollar. We wrongly expand
\$(echo "") to the empty string. Fix this by checking if the dollar was escaped.
The parse_util_* functions have a bunch of output parameters. We should
return a parameter bag instead (I think I tried once and failed).
Given
set var a
echo "$var$(echo b)"
the double-quoted string is expanded right-to-left, so we construct an
intermediate "$varb". Since the variable "varb" is undefined, this wrongly
expands to the empty string (should be "ab"). Fix this by isolating the
expanded command substitution internally. We do the same when handling
unquoted command substitutions.
Fixes#8849
Commit e40eba358 (Treat text following quoted command substitution
as quoted) made parse_util_locate_cmdsubst_range() aware of quoted
command substitutions, by skipping surrounding text via quote_end().
However, it was not quite right. We fail to properly parse
two consecutive command substitutions in the same string,
because we don't maintain the quoting context across calls to
parse_util_locate_cmdsubst_range(). Let's track that bit in a
parameter. This allows us to get rid of the quote_end() hack.
Also apply this to the other place where we call
parse_util_locate_cmdsubst_range() in a loop (highlighting).
Fixes#8500
Commit ec3d3a481 (Support "$(cmd)" command substitution without line
splitting, 2021-07-02) started treating an input string like
"a$()b" as if it were "a"$()"b". Yet, we do not actually insert the
virtual quotes. Instead we just adapted the definition of when quotes
are closed - hence the changes to quote_end().
parse_util_locate_cmdsubst_range() is aware
of the changes to quote_end() but some of its
callers like parse_util_detect_errors_in_argument() and
highlighter_t::color_as_argument() are not. They split strings at
command substitution boundaries without handling the special quoting
rules. (Only the expansion logic did it right.)
Fix this by handling the special quoting rules inside
parse_util_locate_cmdsubst_range(). This is a bit hacky since it
makes it harder for callers to process some substrings in between
command substitutions, but that's okay because current callers only
care about what's inside the command substitutions.
Fixes#8394
This adds a hack to the parser. Given a command
echo "x$()y z"
we virtually insert double quotes before and after the command
substitution, so the command internally looks like
echo "x"$()"y z"
This hack allows to reuse the existing logic for handling (recursive)
command substitutions.
This makes the quoting syntax more complex; external highlighters
should consider adding this if possible.
The upside (more Bash compatibility) seems worth it.
Closes#159
