Re: [PATCH] coroutines: Use cp_build_init_expr consistently.

[Iain Sandoe <iain@sandoe.co.uk>]

Hi Jason

> On 11 Oct 2022, at 23:06, Jason Merrill <jason@redhat.com> wrote:
> 
> On 10/11/22 17:58, Iain Sandoe wrote:
>> Tested on x86_64-darwin19, OK for master?
>> thanks
>> Iain
>> -- >8 --
>> Now we have the TARGET_EXPR_ELIDING_P flag, it is important to ensure it
>> is set properly on target exprs.  The code here has a mixture of APIs used
>> to build inits.  This patch changes that to use cp_build_init_expr() where
>> possible, since that handles setting the flag.
> 
> Hmm, I wouldn't expect this to be necessary, since cp_build_modify_expr calls cp_build_init_expr for INIT_EXPR.

It seems that path is only taken if the init is a CONSTRUCTOR.

>  Perhaps the similarity of the function names is a trap...

not sure exactly what trap you mean.

It seems that on my local set of additional tests (for some of the open prs) there are some
progressions from this change, I will have to track down which change is the cause.

thanks
Iain

> 
>> ---
>>  gcc/cp/coroutines.cc | 25 ++++++++-----------------
>>  1 file changed, 8 insertions(+), 17 deletions(-)
>> diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
>> index 01a3e831ee5..20d309445eb 100644
>> --- a/gcc/cp/coroutines.cc
>> +++ b/gcc/cp/coroutines.cc
>> @@ -1025,8 +1025,7 @@ build_co_await (location_t loc, tree a, suspend_point_kind suspend_kind)
>>    else
>>      {
>>        e_proxy = get_awaitable_var (suspend_kind, o_type);
>> -      o = cp_build_modify_expr (loc, e_proxy, INIT_EXPR, o,
>> -				tf_warning_or_error);
>> +      o = cp_build_init_expr (loc, e_proxy, o);
>>      }
>>      /* I suppose we could check that this is contextually convertible to bool.  */
>> @@ -2889,8 +2888,7 @@ flatten_await_stmt (var_nest_node *n, hash_set<tree> *promoted,
>>  	  gcc_checking_assert (!already_present);
>>  	  tree inner = TREE_OPERAND (init, 1);
>>  	  gcc_checking_assert (TREE_CODE (inner) != COND_EXPR);
>> -	  init = cp_build_modify_expr (input_location, var, INIT_EXPR, init,
>> -				       tf_warning_or_error);
>> +	  init = cp_build_init_expr (var, init);
>>  	  /* Simplify for the case that we have an init containing the temp
>>  	     alone.  */
>>  	  if (t == n->init && n->var == NULL_TREE)
>> @@ -3656,8 +3654,7 @@ await_statement_walker (tree *stmt, int *do_subtree, void *d)
>>  	    if (TREE_CODE (cond_inner) == CLEANUP_POINT_EXPR)
>>  	      cond_inner = TREE_OPERAND (cond_inner, 0);
>>  	    location_t sloc = EXPR_LOCATION (SWITCH_STMT_COND (sw_stmt));
>> -	    tree new_s = cp_build_init_expr (sloc, newvar,
>> -				     cond_inner);
>> +	    tree new_s = cp_build_init_expr (sloc, newvar, cond_inner);
>>  	    finish_expr_stmt (new_s);
>>  	    SWITCH_STMT_COND (sw_stmt) = newvar;
>>  	    /* Now add the switch statement with the condition re-
>> @@ -4902,9 +4899,8 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>>  	      if (flag_exceptions)
>>  		{
>>  		  /* This var is now live.  */
>> -		  r = build_modify_expr (fn_start, parm.guard_var,
>> -					 boolean_type_node, INIT_EXPR, fn_start,
>> -					 boolean_true_node, boolean_type_node);
>> +		  r = cp_build_init_expr (fn_start, parm.guard_var,
>> +					  boolean_true_node);
>>  		  finish_expr_stmt (r);
>>  		}
>>  	    }
>> @@ -4948,9 +4944,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>>        r = coro_build_cvt_void_expr_stmt (r, fn_start);
>>        finish_expr_stmt (r);
>>  -      r = build_modify_expr (fn_start, coro_promise_live, boolean_type_node,
>> -			     INIT_EXPR, fn_start, boolean_true_node,
>> -			     boolean_type_node);
>> +      r = cp_build_init_expr (fn_start, coro_promise_live, boolean_true_node);
>>        finish_expr_stmt (r);
>>          promise_dtor
>> @@ -5031,8 +5025,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>>  				       NULL_TREE);
>>        add_decl_expr (gro);
>>        gro_bind_vars = gro;
>> -      r = cp_build_modify_expr (input_location, gro, INIT_EXPR, get_ro,
>> -				tf_warning_or_error);
>> +      r = cp_build_init_expr (gro, get_ro);
>>        /* The constructed object might require a cleanup.  */
>>        if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (gro_type))
>>  	{
>> @@ -5053,9 +5046,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree *destroyer)
>>       cleanup.  */
>>    if (gro_ret_dtor)
>>      {
>> -       r = build_modify_expr (fn_start, coro_gro_live, boolean_type_node,
>> -			      INIT_EXPR, fn_start, boolean_true_node,
>> -			      boolean_type_node);
>> +       r = cp_build_init_expr (fn_start, coro_gro_live, boolean_true_node);
>>        finish_expr_stmt (r);
>>      }
>>    /* Initialize the resume_idx_var to 0, meaning "not started".  */
>