[gcc r11-2862] d: Don't run all permutations for fail_compilation tests.

[Iain Buclaw <ibuclaw@gcc.gnu.org>]

https://gcc.gnu.org/g:3eefc04663f325a1c76fae4d0a54284e71a57eb1

commit r11-2862-g3eefc04663f325a1c76fae4d0a54284e71a57eb1
Author: Iain Buclaw <ibuclaw@gdcproject.org>
Date:   Tue Aug 25 00:28:38 2020 +0200

    d: Don't run all permutations for fail_compilation tests.
    
    Fail compilation tests only check for language errors from the front-end, all
    default option switches do nothing to alter the error.
    
    gcc/testsuite/ChangeLog:
    
            * lib/gdc-utils.exp (gdc-convert-test): Clear PERMUTE_ARGS for
            fail_compilation tests if not set by test file.

Diff:
---
 gcc/testsuite/lib/gdc-utils.exp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/gcc/testsuite/lib/gdc-utils.exp b/gcc/testsuite/lib/gdc-utils.exp
index 0e4f57c756d..37c1620f307 100644
--- a/gcc/testsuite/lib/gdc-utils.exp
+++ b/gcc/testsuite/lib/gdc-utils.exp
@@ -370,6 +370,11 @@ proc gdc-convert-test { base test } {
 	}
 
 	fail_compilation {
+	    # Fail compilation tests only check for language errors from the
+	    # front-end.  No need to run all permutations of the default DFLAGS.
+	    if { $PERMUTE_ARGS == $DEFAULT_DFLAGS } {
+		set PERMUTE_ARGS ""
+	    }
 	    puts $fdout "// { dg-final { output-exists-not } }"
 	}
     }