https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127816
Bug ID: 127816
Summary: [15/16/17 Regression] [OpenMP] metadirective parallel
makes GCC reject otherwise ordinary acceptable
statements
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Keywords: rejects-valid
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
struct S { int x, y; };
void f1 ();
void f2 ();
struct S s;
void t4a (bool c)
{
#pragma omp metadirective when(implementation={vendor(gnu)}: parallel)
if (c) { f1 (); } else { f2 (); }
}
void t4b ()
{
#pragma omp metadirective when(implementation={vendor(gnu)}: parallel)
do { f1 (); } while (0);
}
void t4c ()
{
#pragma omp metadirective when(implementation={vendor(gnu)}: parallel)
s = (struct S){1, 2};
}
My reading of the OpenMP is that these should parse - the statement after the
#pragma is a perfectly ordinary and acceptable full statement (AIUI, anything
that would be permissible if wrapped into a single-statement compound-statement
is itself acceptable). Trunk GCC (with -std=c23 -O2 -fopenmp) disagrees:
<source>: In function 't4a':
<source>:9:21: error: 'else' without a previous 'if'
9 | if (c) { f1 (); } else { f2 (); }
| ^~~~
<source>: In function 't4b':
<source>:14:64: error: expected 'while' at end of input
14 | #pragma omp metadirective when(implementation={vendor(gnu)}:
parallel)
| ^~~~~~~~
cc1: error: expected 'while' at end of input
<source>: In function 't4c':
<source>:21:23: error: expected ';' at end of input
21 | s = (struct S){1, 2};
| ^
| ;
<source>:21:23: error: expected ';' at end of input
21 | s = (struct S){1, 2};
| ^
| ;
...and so do GCC 15 and 16. My guess as to the cause is that the
analyze_metadirective_body function does not properly accept all of the
statements it should. From testing this in C++ with:
struct S { int x, y; };
void f1 ();
void f2 ();
S s;
void t4a (bool c)
{
#pragma omp metadirective when(implementation={vendor(gnu)}: parallel)
if (c) { f1 (); } else { f2 (); }
}
void t4b ()
{
#pragma omp metadirective when(implementation={vendor(gnu)}: parallel)
do { f1 (); } while (0);
}
void t4c ()
{
#pragma omp metadirective when(implementation={vendor(gnu)}: parallel)
s = S{1, 2};
}
...the same bug also appears to be same, with the same function name in the C++
parser, too.
