From 7e2207a07979b6c1b206024e83e22ca2bbd4e17c Mon Sep 17 00:00:00 2001 From: Eli Schwartz Date: Mon, 10 Jun 2024 22:02:37 -0400 Subject: [PATCH] make building work again when flex is not installed This explicitly reverts commit eec7cdf03dda2bd26e320ead73b91da5a9d86443 because it was a bad idea. The motivating bug report was https://github.com/LudovicRousseau/PCSC/issues/124 and the issue there occurred when building from a git clone, running ./bootstrap && ./configure && make, and having: - configure succeed - make "succeeeds" at having $LEX run, do nothing and fail to generate required sources - compiling nonexistent files fail with highly confusing errors The autoconf manual has always documented the correct way to handle this is to check if lex is unavailable, and set it to the famous automake wrapper "missing", which checks if a program is missing at build time rather than at ./configure time, and fails the build if the rule cannot be run. This means: When building from a git clone, if flex is not available then - configure succeeds - make fails to run $LEX, and tells you to install flex The previous attempt to fix the highly confusing error instead resulted in configure erroring out, and saying flex is required, even when it is *not* required because a `make dist` tarball was used, which contains pregenerated tokenparser.c for the express purpose of making flex unnecessary. See autoconf documentation on $LEX: https://www.gnu.org/software/autoconf/manual/autoconf-2.72/html_node/Particular-Programs.html#index-AC_005fPROG_005fLEX-1 And automake documentation on why to use "missing": https://www.gnu.org/software/automake/manual/html_node/maintainer_002dmode.html Signed-off-by: Eli Schwartz --- configure.ac | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/configure.ac b/configure.ac index eb2370f..c012f2a 100644 --- a/configure.ac +++ b/configure.ac @@ -33,7 +33,10 @@ AC_PROG_INSTALL AC_PROG_MAKE_SET AC_PROG_LN_S AC_PROG_LEX([noyywrap]) -AS_IF([test $LEX = ":"], [AC_MSG_ERROR([no lex or flex found])]) +AS_IF([test $LEX = ":"], [ + AM_MISSING_PROG(MISSINGLEX, [flex]) + LEX=$MISSINGLEX] +) AM_PROG_AR PKG_PROG_PKG_CONFIG @@ -331,4 +334,3 @@ AC_CONFIG_FILES(Makefile examples/Makefile) AC_OUTPUT - -- 2.44.2