1 files changed, 55 insertions, 0 deletions
diff --git a/src/gl/m4/parse-datetime.m4 b/src/gl/m4/parse-datetime.m4
new file mode 100644
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+++ b/src/gl/m4/parse-datetime.m4
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+# parse-datetime.m4 serial 26
+dnl Copyright (C) 2002-2006, 2008-2021 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl Define HAVE_COMPOUND_LITERALS if the C compiler supports compound literals
+dnl as in ISO C99.
+dnl Note that compound literals such as (struct s) { 3, 4 } can be used for
+dnl initialization of stack-allocated variables, but are not constant
+dnl expressions and therefore cannot be used as initializer for global or
+dnl static variables (even though gcc supports this in pre-C99 mode).
+AC_DEFUN([gl_C_COMPOUND_LITERALS],
+[
+  AC_CACHE_CHECK([for compound literals], [gl_cv_compound_literals],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[struct s { int i, j; };]],
+          [[struct s t = (struct s) { 3, 4 };
+            if (t.i != 0) return 0;]])
+       ],
+       [gl_cv_compound_literals=yes],
+       [gl_cv_compound_literals=no])
+    ])
+  if test $gl_cv_compound_literals = yes; then
+    AC_DEFINE([HAVE_COMPOUND_LITERALS], [1],
+      [Define if you have compound literals.])
+  fi
+])
+
+AC_DEFUN([gl_PARSE_DATETIME],
+[
+  dnl parse-datetime.c is generated from parse-datetime.y. It requires bison,
+  dnl because parse-datetime.y uses bison specific features. It requires at
+  dnl least bison-2.4 for %define api.pure.
+  dnl bison is only needed for the maintainer (who touches parse-datetime.y).
+  dnl But in order to avoid separate Makefiles or --enable-maintainer-mode,
+  dnl we put the rule in general Makefile. Now, some people carelessly touch
+  dnl the files or have a broken "make" program, hence the parse-datetime.c
+  dnl rule will sometimes fire. To avoid an error, defines PARSE_DATETIME_BISON
+  dnl to ":" if it is not present or too old.
+  gl_PROG_BISON([PARSE_DATETIME_BISON], [2.4])
+
+  dnl Prerequisites of lib/parse-datetime.h.
+  AC_REQUIRE([AM_STDBOOL_H])
+  AC_REQUIRE([gl_TIMESPEC])
+  AC_REQUIRE([AC_C_RESTRICT])
+
+  dnl Prerequisites of lib/parse-datetime.y.
+  AC_REQUIRE([gl_BISON])
+  AC_REQUIRE([gl_C_COMPOUND_LITERALS])
+  AC_STRUCT_TIMEZONE
+  AC_REQUIRE([gl_CLOCK_TIME])
+  AC_REQUIRE([gl_TM_GMTOFF])
+])