Re: [PATCH 3/4] pkl, testsuite, doc: Allow trailing comma in struct literals

[Jose E. Marchesi]

Hi Eric.

    * src/pkl-tab.y (opt_comma): New rule.
    (array): Use it to simplify trailing comma in arrays.
    (struct, expression): Allow trailing comma in struct literals.
    * doc/poke.texi (Struct Literals): Document it.
    * testsuite/poke.pkl/structs-5.pk: Test it.
    * etc/poke.g4 (array, struct): Match the real grammar.

This is OK for master.
Thanks!

    ---
     ChangeLog                       |  9 +++++++++
     doc/poke.texi                   |  3 ++-
     etc/poke.g4                     | 11 ++++++++---
     src/pkl-tab.y                   | 19 ++++++++-----------
     testsuite/poke.pkl/structs-5.pk |  4 ++++
     5 files changed, 31 insertions(+), 15 deletions(-)
     create mode 100644 testsuite/poke.pkl/structs-5.pk
    
    diff --git a/ChangeLog b/ChangeLog
    index 1323835d..fa8bb600 100644
    --- a/ChangeLog
    +++ b/ChangeLog
    @@ -1,3 +1,12 @@
    +2020-02-25  Eric Blake  <address@hidden>
    +
    +   * src/pkl-tab.y (opt_comma): New rule.
    +   (array): Use it to simplify trailing comma in arrays.
    +   (struct, expression): Allow trailing comma in struct literals.
    +   * doc/poke.texi (Struct Literals): Document it.
    +   * testsuite/poke.pkl/structs-5.pk: Test it.
    +   * etc/poke.g4 (array, struct): Match the real grammar.
    +
     2020-02-25  Eric Blake  <address@hidden>
    
        maint: Fix syntax-check
    diff --git a/doc/poke.texi b/doc/poke.texi
    index 5b729262..6951db15 100644
    --- a/doc/poke.texi
    +++ b/doc/poke.texi
    @@ -2389,7 +2389,8 @@ Struct Literals
    
     The contents of the struct literal is a possibly empty set of fields.
     Each field has an optional name @var{field_name} and a value
    -@var{exp}.  The expression for the value can be of any type.
    +@var{exp}.  The expression for the value can be of any type.  For
    +convenience, a trailing comma is accepted but not required.
    
     @c XXX document struct constructors once they are supported.
    
    diff --git a/etc/poke.g4 b/etc/poke.g4
    index 23cd046d..3aebbecb 100644
    --- a/etc/poke.g4
    +++ b/etc/poke.g4
    @@ -113,7 +113,7 @@ expression:
        | expression 'in' expression
        | expression 'as' simple_type_specifier
        | expression 'isa' simple_type_specifier
    -    | TYPENAME '{' struct_field_list '}'
    +    | TYPENAME '{' struct_field_list opt_comma '}'
         | UNIT
         | expression UNIT
        | struct
    @@ -161,8 +161,13 @@ funcall_arg:
             expression
         ;
    
    +opt_comma:
    +        /* Empty */
    +   | ','
    +    ;
    +
     struct:
    -        'struct' '{' struct_field_list '}'
    +        'struct' '{' struct_field_list opt_comma '}'
        ;
    
     struct_field_list:
    @@ -177,7 +182,7 @@ struct_field:
         ;
    
     array:
    -        '[' array_initializer_list ']'
    +        '[' array_initializer_list opt_comma ']'
        ;
    
     array_initializer_list:
    diff --git a/src/pkl-tab.y b/src/pkl-tab.y
    index d06500d7..cf63b3b7 100644
    --- a/src/pkl-tab.y
    +++ b/src/pkl-tab.y
    @@ -724,7 +724,7 @@ expression:
                                                   $1, $3, $5);
                       PKL_AST_LOC ($$) = @$;
                     }
    -        | TYPENAME '{' struct_field_list '}'
    +        | TYPENAME '{' struct_field_list opt_comma '}'
                {
                       pkl_ast_node type;
                       pkl_ast_node astruct;
    @@ -929,8 +929,13 @@ funcall_arg:
                     }
             ;
    
    +opt_comma:
    +     %empty
    +   | ','
    +        ;
    +
     struct:
    -     STRUCT '{' struct_field_list '}'
    +     STRUCT '{' struct_field_list opt_comma '}'
                {
                         $$ = pkl_ast_make_struct (pkl_parser->ast,
                                                   0 /* nelem */, $3);
    @@ -967,15 +972,7 @@ struct_field:
             ;
    
     array:
    -     '[' array_initializer_list ']'
    -           {
    -                    $$ = pkl_ast_make_array (pkl_parser->ast,
    -                                             0 /* nelem */,
    -                                             0 /* ninitializer */,
    -                                             $2);
    -                    PKL_AST_LOC ($$) = @$;
    -                }
    -        | '[' array_initializer_list ',' ']'
    +     '[' array_initializer_list opt_comma ']'
                {
                         $$ = pkl_ast_make_array (pkl_parser->ast,
                                                  0 /* nelem */,
    diff --git a/testsuite/poke.pkl/structs-5.pk 
b/testsuite/poke.pkl/structs-5.pk
    new file mode 100644
    index 00000000..fdf73424
    --- /dev/null
    +++ b/testsuite/poke.pkl/structs-5.pk
    @@ -0,0 +1,4 @@
    +/* { dg-do run } */
    +
    +/* { dg-command { struct { 1, 2, } } } */
    +/* { dg-output "struct {1,2}" } */