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| author | Eric Blake <eblake@redhat.com> | 2014-07-17 14:52:57 -0600 |
|---|---|---|
| committer | Eric Blake <eblake@redhat.com> | 2014-07-17 15:40:12 -0600 |
| commit | 0443fa8d4320b3f42a7774c470cc40921cf74d00 (patch) | |
| tree | ab26c21d3b6584a3a9f68dad77b95622bd125e2c /lib/m4sugar/m4sh.m4 | |
| parent | 5dcda009ef77b657e5a78ad88774fe50c5088abc (diff) | |
| download | autoconf-0443fa8d4320b3f42a7774c470cc40921cf74d00.tar.gz | |
m4sh: allow trailing newlines in shell conditions
Dimitrios Apostolou reported getting a shell syntax error for
this construct in his configure.ac:
AM_CONDITIONAL([HAVE_LIBXML2],
[test "x$with_libxml2" != xno &&
test "x$ac_cv_lib_xml2_xmlFirstElementChild" = xyes]
)
He analyzed it to a root cause: his trailing newline, coupled
with an 'if $2; then' construct in the macro body, resulted in
configure containing:
if test ... xyes
; then
where the semicolon is a syntax error in shell; and proposed
a patch to automake to fix his use case.
While that macro is not under our control, it does highlight
the fact that the shell can use either ; or newline to
terminate a conditional prior to the next keyword in a compound
statement. If we use newline, we gain two benefits - the
configure file is slightly smaller (more lines, but fewer
bytes), and any user that doesn't realize that unquoted
trailing newlines in a macro argument are still significant
can still generate valid shell code when their argument is
used in a shell compound statement.
* lib/m4sugar/m4sh.m4 (AS_IF, _AS_IF, _AS_CLEAN_DIR): Prefer
newline over semicolon to end user-supplied conditionals.
* lib/autoconf/general.m4 (AC_CONFIG_AUX_DIRS): Likewise.
* lib/autoconf/libs.m4 (AC_SEARCH_LIBS): Likewise.
* lib/autoconf/programs.m4 (_AC_PATH_PROGS_FEATURE_CHECK):
Likewise.
* tests/m4sh.at (AS_IF and AS_CASE): Test it.
Signed-off-by: Eric Blake <eblake@redhat.com>
Diffstat (limited to 'lib/m4sugar/m4sh.m4')
| -rw-r--r-- | lib/m4sugar/m4sh.m4 | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/lib/m4sugar/m4sh.m4 b/lib/m4sugar/m4sh.m4 index 91cdeac5..a94999e7 100644 --- a/lib/m4sugar/m4sh.m4 +++ b/lib/m4sugar/m4sh.m4 @@ -618,9 +618,11 @@ done[]_m4_popdef([$1])]) # AS_IF(TEST1, [IF-TRUE1 = :]...[IF-FALSE = :]) # --------------------------------------------- # Expand into -# | if TEST1; then +# | if TEST1 +# | then # | IF-TRUE1 -# | elif TEST2; then +# | elif TEST2 +# | then # | IF-TRUE2 # [...] # | else @@ -629,7 +631,8 @@ done[]_m4_popdef([$1])]) # with simplifications when IF-TRUE1 and/or IF-FALSE are empty. # m4_define([_AS_IF], -[elif $1; then : +[elif $1 +then : $2 ]) m4_define([_AS_IF_ELSE], @@ -639,7 +642,8 @@ m4_define([_AS_IF_ELSE], ])]) m4_defun([AS_IF], -[if $1; then : +[if $1 +then : $2 m4_map_args_pair([_$0], [_$0_ELSE], m4_shift2($@))]dnl [fi[]])# AS_IF @@ -1389,7 +1393,8 @@ _ASBOX]) # Remove all contents from within DIR, including any unwritable # subdirectories, but leave DIR itself untouched. m4_define([_AS_CLEAN_DIR], -[if test -d $1; then +[if test -d $1 +then find $1 -type d ! -perm -700 -exec chmod u+rwx {} \; rm -fr $1/* $1/.[[!.]] $1/.??* fi]) |