There is already in use:
lit/lit-lldb-init:settings set symbols.enable-external-lookup false packages/Python/lldbsuite/test/lldbtest.py: self.runCmd('settings set symbols.enable-external-lookup false')
But those are not in effect during MI part of the testsuite. Another problem is that symbols.enable-external-lookup (read by GetEnableExternalLookup) has been currently read only by LocateMacOSXFilesUsingDebugSymbols and therefore it had no effect on Linux.
On Red Hat platforms (Fedoras, RHEL-7) there is DWZ in use and so MiSyntaxTestCase-test_lldbmi_output_grammar FAILs due to:
AssertionError: error: inconsistent pattern ''^.+?\n'' for state 0x5f (matched string: warning: (x86_64) /lib64/libstdc++.so.6 unsupported DW_FORM values: 0x1f20 0x1f21
It is the only testcase with this error. It happens due to:
(lldb) target create "/lib64/libstdc++.so.6" Current executable set to '/lib64/libstdc++.so.6' (x86_64). (lldb) b main warning: (x86_64) /lib64/libstdc++.so.6 unsupported DW_FORM values: 0x1f20 0x1f21 Breakpoint 1: no locations (pending). WARNING: Unable to resolve breakpoint to any actual locations.
which happens only with gcc-base-debuginfo rpm installed (similarly for other packages).
It should also speed up the testsuite as it no longer needs to read /usr/lib/debug symbols which have no effect (and should not have any effect) on the testsuite results.