SERVER-48348 Do not sort dwo files in ahead of object files during Ninja generation

1 files changed, 11 insertions, 2 deletions

diff --git a/site_scons/site_tools/ninja_next.py b/site_scons/site_tools/ninja_next.py
index 507e6685f2b..f999b746560 100644
--- a/site_scons/site_tools/ninja_next.py
+++ b/site_scons/site_tools/ninja_next.py
@@ -650,7 +650,16 @@ class NinjaState:
             # use for the "real" builder and multiple phony targets that
             # match the file names of the remaining outputs. This way any
             # build can depend on any output from any build.
-            build["outputs"].sort()
+            #
+            # We assume that the first listed output is the 'key'
+            # output and is stably presented to us by SCons. For
+            # instance if -gsplit-dwarf is in play and we are
+            # producing foo.o and foo.dwo, we expect that outputs[0]
+            # from SCons will be the foo.o file and not the dwo
+            # file. If instead we just sorted the whole outputs array,
+            # we would find that the dwo file becomes the
+            # first_output, and this breaks, for instance, header
+            # dependency scanning.
             if rule is not None and (rule.get("deps") or rule.get("rspfile")):
                 first_output, remaining_outputs = (
                     build["outputs"][0],
@@ -659,7 +668,7 @@ class NinjaState:
 
                 if remaining_outputs:
                     ninja.build(
-                        outputs=remaining_outputs, rule="phony", implicit=first_output,
+                        outputs=sorted(remaining_outputs), rule="phony", implicit=first_output,
                     )
 
                 build["outputs"] = first_output