Re: yacc: beware of GCC9 warnings in push mode

[Akim Demaille]

> commit c30c6b651973da07f3b28f23c3e4ff5f69f32082
> Author: Akim Demaille <address@hidden>
> Date:   Sun Oct 20 13:55:36 2019 +0200
> 
>    yacc: beware of GCC9 warnings in push mode


I'm not going to push this.  I had not read the warning carefully enough:
1. I'm not fixing the right code
2. Woot?  It complains about the LHS of the assignment.  I don't get it.
   But we already addressed the exact same issue with GCC7 (not GCC8 though).

So I installed this instead.

commit 41b1f828ae39518d75948035c99ba053bc402752
Author: Akim Demaille <address@hidden>
Date:   Sun Oct 20 13:55:36 2019 +0200

    tests: beware of GCC9 warnings in push mode
    
    This is really weird: GCC points to the LHS of the assignment...
    
        260. headers.at:184: testing Sane headers: api.pure api.push-pull=both 
...
        tests/headers.at:184: COLUMNS=1000; export COLUMNS;  bison --color=no 
-fno-caret -d -o input.c input.y
        tests/headers.at:184: $CC $CFLAGS $CPPFLAGS  -c -o input.o input.c
        stderr:
        input.c: In function 'yyparse':
        input.c:1276:16: error: 'yylval' may be used uninitialized in this 
function [-Werror=maybe-uninitialized]
         1276 |         yylval = *yypushed_val;
              |         ~~~~~~~^~~~~~~~~~~~~~~
        input.c: In function 'yypull_parse':
        input.c:1276:16: error: 'yylval' may be used uninitialized in this 
function [-Werror=maybe-uninitialized]
         1276 |         yylval = *yypushed_val;
              |         ~~~~~~~^~~~~~~~~~~~~~~
        cc1: all warnings being treated as errors
        stdout:
        tests/headers.at:184: exit code was 1, expected 0
    
    See also d87c8ac79ab844d6a7a4f5103dcf7a842d18b611
    and 9645a2b20ee7cbfa8bb4ac2237f87d598afe349c.
    
    * tests/headers.at (Several parsers, Several parsers): Disable these
    warnings when in push parser.

diff --git a/tests/headers.at b/tests/headers.at
index 390dfa4c..11d60f16 100644
--- a/tests/headers.at
+++ b/tests/headers.at
@@ -129,7 +129,7 @@ AT_DATA_GRAMMAR([input.y],
 %code {
 #include <stdio.h> /* printf. */
 ]AT_PUSH_IF([[
-#if defined __GNUC__ && 7 == __GNUC__
+#if defined __GNUC__ && (7 == __GNUC__ || 9 == __GNUC__)
 # pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
 #endif
 ]])[
@@ -215,7 +215,7 @@ $2
 %{
 #include <stdio.h> /* printf. */
 ]AT_PUSH_IF([[
-#if defined __GNUC__ && 7 == __GNUC__
+#if defined __GNUC__ && (7 == __GNUC__ || 9 == __GNUC__)
 # pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
 #endif
 ]])[