On Fuchsia builds with symbol_level=2, addr2line is unable to resolve line numbers for stack trace entries. Instead it outputs outputting "??" instead, like this:

"testing::UnitTest::Run() at ??:?"

Rebuilding the binary with symbol_level=1 fixes the problem. thakis@ said that symbol level 2 should contain a superset of level 1's debug information, so any fidelity loss should be treated as a bug.


Repro steps:

1. Add a simple unit test to a suite which outputs a stack trace to the console.

TEST_F(StackTraceTest, PrintTrace) {
  base::debug::StackTrace().Print();
}

2. Set up an output dir to build with Fuchsia.

target_os = "fuchsia"
is_debug = true
dcheck_always_on = true
is_component_build = false
use_goma = true
symbol_level = 2

3. Build the unit test binary.
4. Run the unit test with --single-process-test , so that you can see the test's output on stdio.

Expected: a symbolized stack trace with line numbers, like this:

  #00: StackTrace at base/debug/stack_trace_fuchsia.cc:173

Actual: unsymbolized entries like this (the script is set up to pass through output as-is, if symbolization contains questionmarks):

  #00: pc 0x16fb5f4c510 (app:./base_unittests,0x2523510)