Re: [PATCH] enum: support declarations with a trailing comma

[Kris Van Hees <kris.van.hees@oracle.com>]

Nice patch.  But I think it should also have an error test that verifies that
having a missing enumerator (i.e. have ,, in the enumeration list) is indeed
still an error.

On Wed, Sep 03, 2025 at 03:51:04PM +0100, Alan Maguire wrote:
> When doing python tracing, it was recently observed that #include'ing
> a file with enum declarations with trailing commas fails; this is
> due to the D grammar being strict about the last enumerator value
> not having a trailing comma.  So
> 
> typedef enum foo {
> 	BAR,
> 	BAZ
> };
> 
> is permitted, but
> 
> typdef enum foo {
> 	BAR,
> 	BAZ,
> };
> 
> is not.  The latter pattern is used quite frequently in #include
> files, especially where conditional compilation of some enum
> values is done.
> 
> Relax this constraint and add a test to validate that D compilation
> succeeds with the trailing comma in an enum declaration.
> 
> Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
> ---
>  libdtrace/dt_grammar.y                     |  3 +-
>  test/unittest/enum/tst.EnumTrailingComma.d | 36 ++++++++++++++++++++++
>  2 files changed, 38 insertions(+), 1 deletion(-)
>  create mode 100644 test/unittest/enum/tst.EnumTrailingComma.d
> 
> diff --git a/libdtrace/dt_grammar.y b/libdtrace/dt_grammar.y
> index 677cd869..7984b85d 100644
> --- a/libdtrace/dt_grammar.y
> +++ b/libdtrace/dt_grammar.y
> @@ -702,7 +702,8 @@ enum_definition:
>  
>  enumerator_list:
>  		enumerator
> -	|	enumerator_list DT_TOK_COMMA enumerator
> +	|	enumerator DT_TOK_COMMA enumerator_list
> +	|	enumerator DT_TOK_COMMA
>  	;
>  
>  enumerator:	DT_TOK_IDENT { dt_decl_enumerator($1, NULL); }
> diff --git a/test/unittest/enum/tst.EnumTrailingComma.d b/test/unittest/enum/tst.EnumTrailingComma.d
> new file mode 100644
> index 00000000..0414498b
> --- /dev/null
> +++ b/test/unittest/enum/tst.EnumTrailingComma.d
> @@ -0,0 +1,36 @@
> +/*
> + * Oracle Linux DTrace.
> + * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
> + * Licensed under the Universal Permissive License v 1.0 as shown at
> + * http://oss.oracle.com/licenses/upl.
> + */
> +
> +/*
> + * ASSERTION:
> + * Enumerations should support declaration with a trailing comma for
> + * the last enumeration value.
> + *
> + * SECTION: Type and Constant Definitions/Enumerations
> + *
> + * NOTES:
> + *
> + */
> +
> +#pragma D option quiet
> +
> +enum colors {
> +	RED = 1,
> +	GREEN = 2,
> +	BLUE = 3, 
> +};
> +
> +enum shapes {
> +	CIRCLE,
> +	SQUARE,
> +	TRIANGLE,
> +};
> +
> +BEGIN
> +{
> +	exit(0);
> +}
> -- 
> 2.43.5
>