A struct declaration with variables is now absorbed into the 'declaration'
rule, like any other variable declaration.
A struct declaration without variables is now reduced to the
'struct_declaration_without_vars' rule.
They both are reduced to a 'declaration_statement' in the end.
In a declaration with multiple variables, the variables must be created
before the initializer of the next variable is parsed. This is required
for initializers such as:
float a = 1, b = a, c = b + 1;
A requisite for this is that the type information is parsed in the same
rule as the first variable (as a variable_def_typed) so it is
immediately available to declare the first variable. Then, the next
untyped variable declaration is parsed, and the type from the first
variable can be used to declare the second, before the third is parsed,
and so on.
Basically, declare_vars() is separated in three functions:
1. check_invalid_in_out_modifiers(), which is to be called once per
declaration and emits an error when in or out modifiers are used for
these non-parameter variables.
2. declare_var(), which now handles one variable at the time and doesn't
free any memory.
3. initialize_vars(), which takes care of preparing the initialization
instructions of several variables and frees their struct
parse_variable_def, using exclusively free_parse_variable_def().
This allows to declare variables individually before the initializer of
the next variable in the same declaration is parsed, which is used in
the following patches.
Also, simplifies memory management.
This patch makes index expressions on resources hlsl_ir_index nodes
instead of hlsl_ir_resource_load nodes, because it is not known if they
will be used later as the lhs of an hlsl_ir_resource_store.
For now, the only benefit is consistency.
Otherwise, in the added test, we get:
vkd3d-compiler: vkd3d-shader/hlsl.c:452: hlsl_init_deref_from_index_chain: Assertion `chain' failed.
because on the path that triggers the following error:
E5002: Wrong type for argument 1 of 'tex3D': expected 'sampler' or 'sampler3D', but got 'sampler2D'.
a NULL params.resource is passed to hlsl_new_resource_load() and
then to hlsl_init_deref_from_index_chain().
