[PATCH] tbb-backend effective target should check ability to link TBB

[Thomas Rodgers]

I have it fixed locally, but yeah I have not yet committed it.

Jonathan Wakely writes:

> On 25/04/19 15:58 -0700, Thomas Rodgers wrote:
>>
>>	PR libstdc++/90252
>>	* testsuite/lib/libstdc++.exp (check_effective_target_tbb-backend):
>>	Changed v3_target_compile check from preprocess to executable.
>>---
>> libstdc++-v3/testsuite/lib/libstdc++.exp | 9 +++++++--
>> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> This patch is still pending, but I think it's missing -ltbb that would
> actually make the link succeed, isn't it?
>
>>diff --git a/libstdc++-v3/testsuite/lib/libstdc++.exp b/libstdc++-v3/testsuite/lib/libstdc++.exp
>>index c48b4d78bbb..fa61bccc9f6 100644
>>--- a/libstdc++-v3/testsuite/lib/libstdc++.exp
>>+++ b/libstdc++-v3/testsuite/lib/libstdc++.exp
>>@@ -1612,15 +1612,20 @@ proc check_effective_target_tbb-backend { } {
>>     # Set up and preprocess a C++ test program that depends
>>     # on tbb
>>     set src tbb_backend[pid].cc
>>-
>>+    set exe tbb_backend[pid].x
>>+
>>     set f [open $src "w"]
>>     puts $f "#include <tbb/tbb.h>"
>>     puts $f "#if TBB_INTERFACE_VERSION < 10000"
>>     puts $f "#  error Intel(R) Threading Building Blocks 2018 is required; older versions are not supported."
>>     puts $f "#endif"
>>+    puts $f "int main ()"
>>+    puts $f "{"
>>+    puts $f "  return 0;"
>>+    puts $f "}"
>>     close $f
>>
>>-    set lines [v3_target_compile $src /dev/null preprocess ""]
>>+    set lines [v3_target_compile $src $exe executable ""]
>>     file delete $src
>>
>>     if [string match "" $lines] {
>> -- 
>>2.20.1
>>