Re: building without json prerequisite

[Jose E. Marchesi]

Hi Bruno.

    The HACKING file says that the JSON-C library is optional:
      "If this library is not found, poke will build without MI support."
    
    That's not what happens now. Instead, a build failure occurs during
    "make check":
    
    gcc -DHAVE_CONFIG_H -I. -I../../poke -I../../gl -I../../gl
    -I../../poke -I../../poke -I/inst-x86_64-64/include -Wall -g -O2 -MT
    ../../poke/mi_json-pk-mi-json.o -MD -MP -MF
    ../../poke/.deps/mi_json-pk-mi-json.Tpo -c -o
    ../../poke/mi_json-pk-mi-json.o `test -f '../../poke/pk-mi-json.c' ||
    echo './'`../../poke/pk-mi-json.c
    ../../poke/pk-mi-json.c:23:18: fatal error: json.h: No such file or 
directory
    compilation terminated.
    make[3]: *** [Makefile:1858: ../../poke/mi_json-pk-mi-json.o] Error 1
    make[3]: Leaving directory '/POKE/poke/testsuite/poke.mi-json'
    make[2]: *** [Makefile:1963: check-am] Error 2
    
    The attached patch
    1) avoids building code that won't build,
    2) avoids a "make check" error message
      Running /POKE/poke/testsuite/poke.mi-json/mi-json.exp ...
      ERROR: The executable, "poke.mi-json/mi-json" is missing
      ERROR: mi-json had an execution error
    
    With this, the continuous integration should work fine again.
    
    OK to push?

OK for master.
Thanks!
    
    >From b5597d6671ed9393f089ab071b9f54157b6280f2 Mon Sep 17 00:00:00 2001
    From: Bruno Haible <bruno@clisp.org>
    Date: Tue, 14 Jul 2020 20:44:38 +0200
    Subject: [PATCH] Fix build failure during "make check" without libjson-c.
    
    * testsuite/poke.mi-json/Makefile.am: Don't build anything if POKE_MI is
    false.
    * testsuite/poke.mi-json/mi-json.exp: Don't run any test if
    poke.mi-json/mi-json wasn't built.
    ---
     ChangeLog                          | 8 ++++++++
     testsuite/poke.mi-json/Makefile.am | 4 ++++
     testsuite/poke.mi-json/mi-json.exp | 9 ++++++---
     3 files changed, 18 insertions(+), 3 deletions(-)
    
    diff --git a/ChangeLog b/ChangeLog
    index 71a8d8d..d23f4bc 100644
    --- a/ChangeLog
    +++ b/ChangeLog
    @@ -1,3 +1,11 @@
    +2020-07-14  Bruno Haible  <bruno@clisp.org>
    +
    +   Fix build failure during "make check" without libjson-c.
    +   * testsuite/poke.mi-json/Makefile.am: Don't build anything if POKE_MI is
    +   false.
    +   * testsuite/poke.mi-json/mi-json.exp: Don't run any test if
    +   poke.mi-json/mi-json wasn't built.
    +
     2020-07-14  Jose E. Marchesi  <jemarch@gnu.org>
     
        * poke/poke.c (pk_print_version): Change jemarch for "the poke
    diff --git a/testsuite/poke.mi-json/Makefile.am 
b/testsuite/poke.mi-json/Makefile.am
    index c710e5a..2e1ae7a 100644
    --- a/testsuite/poke.mi-json/Makefile.am
    +++ b/testsuite/poke.mi-json/Makefile.am
    @@ -15,6 +15,8 @@
     
     AUTOMAKE_OPTIONS = subdir-objects
     
    +if POKE_MI
    +
     check_PROGRAMS = mi-json
     
     mi_json_SOURCES = mi-json.c \
    @@ -26,3 +28,5 @@ mi_json_CPPFLAGS = -I$(top_builddir)/gl 
-I$(top_srcdir)/gl \
     
     mi_json_CFLAGS = $(JSON_C_CFLAGS)
     mi_json_LDADD = $(JSON_C_LIBS) $(top_builddir)/gl/libgnu.la
    +
    +endif
    diff --git a/testsuite/poke.mi-json/mi-json.exp 
b/testsuite/poke.mi-json/mi-json.exp
    index f28f539..5c3beb7 100644
    --- a/testsuite/poke.mi-json/mi-json.exp
    +++ b/testsuite/poke.mi-json/mi-json.exp
    @@ -1,6 +1,9 @@
     load_lib "dejagnu.exp"
     
    -# Execute the test cases, and analyse the output
    -if { [host_execute "poke.mi-json/mi-json"] ne "" } {
    -    perror "mi-json had an execution error" 0
    +# Skip this test if poke.mi-json/mi-json wasn't built.
    +if { [file exists "poke.mi-json/mi-json"] } {
    +    # Execute the test cases, and analyse the output
    +    if { [host_execute "poke.mi-json/mi-json"] ne "" } {
    +        perror "mi-json had an execution error" 0
    +    }
     }