Hi Julian!
On Fri, 28 Sep 2018 14:17:42 +0100, Julian Brown <[email protected]>
wrote:
> On Wed, 26 Sep 2018 14:08:37 -0700
> Cesar Philippidis <[email protected]> wrote:
>
> > On 09/26/2018 12:50 PM, Joseph Myers wrote:
> > > On Wed, 26 Sep 2018, Cesar Philippidis wrote:
> > >
> > >> Attached is an old patch which updated the C and C++ FEs to use
> > >> %<)%> for the right ')' symbol. It's mostly a cosmetic change. All
> > >> of the changes are self-contained to the OpenACC code path.
> > >
> > > Why is the "before ')'" included in the call to c_parser_error at
> > > all? c_parser_error calls c_parse_error which adds its own " before
> > > " and token description or expansion, so I'd expect the current
> > > error to result in a message ending in something of the form
> > > "before X before Y".
>
> > Julian, I need to start working on deep copy in OpenACC. Can you take
> > over this patch? The error handling code in the C FE needs to be
> > removed because it's dead.
>
> I agree that the error-handling path in question in the C FE is dead.
> The difference is that in C, c_parser_oacc_wait_list parses the open
> parenthesis, the list and then the close parenthesis separately, and so
> a token sequence like:
>
> (1
>
> will return an expression list of length 1. In the C++ FE rather, a
> cp_parser_parenthesized_expression_list is parsed all in one go, and if
> the input is not that well-formed sequence then NULL is returned (or a
> zero-length vector for an empty list).
>
> But for C, it does not appear that c_parser_expr_list has a code path
> that can return a zero-length list at all.
In addition to your "(1" token sequence (and similar ones), I suppose
what these code paths in C and C++ are supposed to catch the "wait ()"
case (see line 149 of gcc/testsuite/c-c++-common/goacc/asyncwait-1.c).
I suppose in C, we do diagnose an "error: expected expression before ')'
token" in "c_parser_expr_list"/"c_parser_expr_no_commas", and then return
a list with an "error_mark_node", right? (I have not verified that.)
> So, we can elide the
> diagnostic with no change to compiler behaviour.
In that case, yes.
> This patch does that,
> and also changes the C++ diagnostic, leading to errors being reported
> like:
>
> diag.c: In function 'int main(int, char*)':
> diag.c:6:59: error: expected ')' before end of line
> 6 | #pragma acc parallel copyin (a[0:N]) copy (b[0:N]) wait (1
> | ~ ^
> | )
> diag.c:6:59: error: expected integer expression list before end of line
>
> Actually I'm not too sure how useful the second error line is. Maybe we
> should just remove it to improve consistency between C & C++?
Right, one single error diagnostic is enough.
But please make sure that the "wait ()" case continues to be diagnosed
correctly -- similarly to C, I suggest "expected expression before ')'
token" (or whatever is natural to the C++ parser), and then accordingly
tidy up that "dg-error" regular expression on line 149 of
gcc/testsuite/c-c++-common/goacc/asyncwait-1.c.
In C++, this is the case that: "args != NULL && args->length () == 0", I
suppose? (I have not verified that.)
Oh, and next to "wait ()" please also add test coverage for "wait (".
Grüße
Thomas
> The attached has been tested with offloading to nvptx and bootstrapped.
> OK?
>
> Thanks,
>
> Julian
>
> 2018-XX-YY James Norris <[email protected]>
> Cesar Philippidis <[email protected]>
> Julian Brown <[email protected]>
>
> gcc/c/
> * c-parser.c (c_parser_oacc_wait_list): Remove dead diagnostic
> code.
>
> gcc/cp/
> * parser.c (cp_parser_oacc_wait_list): Change error message.
>
> gcc/testsuite/
> * c-c++-common/goacc/asyncwait-1: Update expected errors.
> commit 3a59bdbccc3c2383c0056c74797d698c7d81dce2
> Author: Julian Brown <[email protected]>
> Date: Fri Sep 28 05:52:55 2018 -0700
>
> OpenACC wait list diagnostic change
>
> diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c
> index 1f173fc..92a8089 100644
> --- a/gcc/c/c-parser.c
> +++ b/gcc/c/c-parser.c
> @@ -11597,14 +11597,6 @@ c_parser_oacc_wait_list (c_parser *parser,
> location_t clause_loc, tree list)
> return list;
>
> args = c_parser_expr_list (parser, false, true, NULL, NULL, NULL, NULL);
> -
> - if (args->length () == 0)
> - {
> - c_parser_error (parser, "expected integer expression before ')'");
> - release_tree_vector (args);
> - return list;
> - }
> -
> args_tree = build_tree_list_vec (args);
>
> for (t = args_tree; t; t = TREE_CHAIN (t))
> diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
> index 6696f17..43128e0 100644
> --- a/gcc/cp/parser.c
> +++ b/gcc/cp/parser.c
> @@ -32086,7 +32086,7 @@ cp_parser_oacc_wait_list (cp_parser *parser,
> location_t clause_loc, tree list)
>
> if (args == NULL || args->length () == 0)
> {
> - cp_parser_error (parser, "expected integer expression before ')'");
> + cp_parser_error (parser, "expected integer expression list");
> if (args != NULL)
> release_tree_vector (args);
> return list;
> diff --git a/gcc/testsuite/c-c++-common/goacc/asyncwait-1.c
> b/gcc/testsuite/c-c++-common/goacc/asyncwait-1.c
> index e1840af..2fc8948 100644
> --- a/gcc/testsuite/c-c++-common/goacc/asyncwait-1.c
> +++ b/gcc/testsuite/c-c++-common/goacc/asyncwait-1.c
> @@ -116,7 +116,7 @@ f (int N, float *a, float *b)
> }
>
> #pragma acc parallel copyin (a[0:N]) copy (b[0:N]) wait (1 /* { dg-error
> "expected '\\\)' before end of line" } */
> - /* { dg-error "expected integer expression before '\\\)'" "" { target
> c++ } .-1 } */
> + /* { dg-error "expected integer expression list before" "" { target c++
> } .-1 } */
> {
> for (ii = 0; ii < N; ii++)
> b[ii] = a[ii];
> @@ -171,7 +171,7 @@ f (int N, float *a, float *b)
> #pragma acc wait (1,2,,) /* { dg-error "expected (primary-|)expression
> before" } */
>
> #pragma acc wait (1 /* { dg-error "expected '\\\)' before end of line" } */
> - /* { dg-error "expected integer expression before '\\\)'" "" { target
> c++ } .-1 } */
> + /* { dg-error "expected integer expression list before" "" { target c++
> } .-1 } */
>
> #pragma acc wait (1,*) /* { dg-error "expected (primary-|)expression before"
> } */
>
