fix(multicore): Domain.join: do not lose backtrace

When an exception from a joined domain is raised, the backtrace is lost.
Instead, the backtrace the user gets indicates that it originated from
Domain.join, as opposed to where the error occurred inside the domain.
We (Semgrep) have started noticing this in CI runs, which makes pinning
the root cause difficult.

Note that this necessitated reordering `Domain` in stdlib/StdlibModules.

Author: dijkstracula

.depend

@@ -9951,7 +9951,6 @@ ocamltest/main.cmo : \
     ocamltest/variables.cmi \
     otherlibs/unix/unix.cmi \
     ocamltest/tsl_semantics.cmi \
-    ocamltest/tsl_parser.cmi \
     ocamltest/tsl_lexer.cmi \
     ocamltest/tsl_ast.cmi \
     ocamltest/translate.cmi \
@@ -9970,8 +9969,7 @@ ocamltest/main.cmx : \
     ocamltest/variables.cmx \
     otherlibs/unix/unix.cmx \
     ocamltest/tsl_semantics.cmx \
-    ocamltest/tsl_parser.cmx \
-    ocamltest/tsl_lexer.cmx \
+    ocamltest/tsl_lexer.cmi \
     ocamltest/tsl_ast.cmx \
     ocamltest/translate.cmx \
     ocamltest/tests.cmx \
@@ -9994,7 +9992,7 @@ ocamltest/modifier_parser.cmo : \
     ocamltest/modifier_parser.cmi
 ocamltest/modifier_parser.cmx : \
     ocamltest/variables.cmx \
-    ocamltest/tsl_lexer.cmx \
+    ocamltest/tsl_lexer.cmi \
     ocamltest/ocamltest_stdlib.cmx \
     ocamltest/environments.cmx \
     ocamltest/modifier_parser.cmi
@@ -10230,19 +10228,13 @@ ocamltest/ocamltest_stdlib.cmo : \
     utils/misc.cmi \
     ocamltest/ocamltest_stdlib.cmi
 ocamltest/ocamltest_stdlib.cmx : \
-    ocamltest/ocamltest_unix.cmx \
+    ocamltest/ocamltest_unix.cmi \
     ocamltest/ocamltest_config.cmx \
     utils/misc.cmx \
     ocamltest/ocamltest_stdlib.cmi
 ocamltest/ocamltest_stdlib.cmi : \
     ocamltest/ocamltest_unix.cmi \
     utils/misc.cmi
-ocamltest/ocamltest_unix.cmo : \
-    otherlibs/unix/unix.cmi \
-    ocamltest/ocamltest_unix.cmi
-ocamltest/ocamltest_unix.cmx : \
-    otherlibs/unix/unix.cmx \
-    ocamltest/ocamltest_unix.cmi
 ocamltest/ocamltest_unix.cmi :
 ocamltest/ocamltest_unix_dummy.cmo :
 ocamltest/ocamltest_unix_dummy.cmx :
@@ -10298,15 +10290,13 @@ ocamltest/tests.cmi : \
     ocamltest/actions.cmi
 ocamltest/translate.cmo : \
     ocamltest/tsl_semantics.cmi \
-    ocamltest/tsl_parser.cmi \
     ocamltest/tsl_lexer.cmi \
     ocamltest/tsl_ast.cmi \
     parsing/location.cmi \
     ocamltest/translate.cmi
 ocamltest/translate.cmx : \
     ocamltest/tsl_semantics.cmx \
-    ocamltest/tsl_parser.cmx \
-    ocamltest/tsl_lexer.cmx \
+    ocamltest/tsl_lexer.cmi \
     ocamltest/tsl_ast.cmx \
     parsing/location.cmx \
     ocamltest/translate.cmi
@@ -10319,24 +10309,7 @@ ocamltest/tsl_ast.cmx : \
     ocamltest/tsl_ast.cmi
 ocamltest/tsl_ast.cmi : \
     parsing/location.cmi
-ocamltest/tsl_lexer.cmo : \
-    ocamltest/tsl_parser.cmi \
-    ocamltest/tsl_lexer.cmi
-ocamltest/tsl_lexer.cmx : \
-    ocamltest/tsl_parser.cmx \
-    ocamltest/tsl_lexer.cmi
-ocamltest/tsl_lexer.cmi : \
-    ocamltest/tsl_parser.cmi
-ocamltest/tsl_parser.cmo : \
-    ocamltest/tsl_ast.cmi \
-    parsing/location.cmi \
-    ocamltest/tsl_parser.cmi
-ocamltest/tsl_parser.cmx : \
-    ocamltest/tsl_ast.cmx \
-    parsing/location.cmx \
-    ocamltest/tsl_parser.cmi
-ocamltest/tsl_parser.cmi : \
-    ocamltest/tsl_ast.cmi
+ocamltest/tsl_lexer.cmi :
 ocamltest/tsl_semantics.cmo : \
     ocamltest/variables.cmi \
     ocamltest/tsl_ast.cmi \
@@ -10376,7 +10349,6 @@ testsuite/lib/testing.cmi :
 testsuite/tools/codegen_main.cmo : \
     utils/profile.cmi \
     testsuite/tools/parsecmmaux.cmi \
-    testsuite/tools/parsecmm.cmi \
     testsuite/tools/lexcmm.cmi \
     asmcomp/emitaux.cmi \
     asmcomp/emit.cmi \
@@ -10387,8 +10359,7 @@ testsuite/tools/codegen_main.cmo : \
 testsuite/tools/codegen_main.cmx : \
     utils/profile.cmx \
     testsuite/tools/parsecmmaux.cmx \
-    testsuite/tools/parsecmm.cmx \
-    testsuite/tools/lexcmm.cmx \
+    testsuite/tools/lexcmm.cmi \
     asmcomp/emitaux.cmx \
     asmcomp/emit.cmx \
     middle_end/compilenv.cmx \
@@ -10434,46 +10405,7 @@ testsuite/tools/expect.cmx : \
     testsuite/tools/expect.cmi
 testsuite/tools/expect.cmi : \
     parsing/location.cmi
-testsuite/tools/lexcmm.cmo : \
-    testsuite/tools/parsecmm.cmi \
-    utils/misc.cmi \
-    parsing/location.cmi \
-    lambda/lambda.cmi \
-    testsuite/tools/lexcmm.cmi
-testsuite/tools/lexcmm.cmx : \
-    testsuite/tools/parsecmm.cmx \
-    utils/misc.cmx \
-    parsing/location.cmx \
-    lambda/lambda.cmx \
-    testsuite/tools/lexcmm.cmi
-testsuite/tools/lexcmm.cmi : \
-    testsuite/tools/parsecmm.cmi
-testsuite/tools/parsecmm.cmo : \
-    testsuite/tools/parsecmmaux.cmi \
-    utils/misc.cmi \
-    parsing/location.cmi \
-    lambda/lambda.cmi \
-    lambda/debuginfo.cmi \
-    utils/config.cmi \
-    asmcomp/cmm.cmi \
-    parsing/asttypes.cmi \
-    asmcomp/arch.cmi \
-    testsuite/tools/parsecmm.cmi
-testsuite/tools/parsecmm.cmx : \
-    testsuite/tools/parsecmmaux.cmx \
-    utils/misc.cmx \
-    parsing/location.cmx \
-    lambda/lambda.cmx \
-    lambda/debuginfo.cmx \
-    utils/config.cmx \
-    asmcomp/cmm.cmx \
-    parsing/asttypes.cmx \
-    asmcomp/arch.cmx \
-    testsuite/tools/parsecmm.cmi
-testsuite/tools/parsecmm.cmi : \
-    parsing/location.cmi \
-    lambda/lambda.cmi \
-    asmcomp/cmm.cmi
+testsuite/tools/lexcmm.cmi :
 testsuite/tools/parsecmmaux.cmo : \
     parsing/location.cmi \
     lambda/lambda.cmi \

stdlib/.depend

@@ -216,6 +216,7 @@ stdlib__Digest.cmi : digest.mli
 stdlib__Domain.cmo : domain.ml \
     stdlib__Sys.cmi \
     stdlib.cmi \
+    stdlib__Printexc.cmi \
     stdlib__Obj.cmi \
     stdlib__Mutex.cmi \
     stdlib__List.cmi \
@@ -226,6 +227,7 @@ stdlib__Domain.cmo : domain.ml \
 stdlib__Domain.cmx : domain.ml \
     stdlib__Sys.cmx \
     stdlib.cmx \
+    stdlib__Printexc.cmx \
     stdlib__Obj.cmx \
     stdlib__Mutex.cmx \
     stdlib__List.cmx \

stdlib/StdlibModules

@@ -70,11 +70,11 @@ STDLIB_MODULE_BASENAMES = \
   mutex \
   condition \
   semaphore \
-  domain \
   camlinternalFormat \
   printf \
   arg \
   printexc \
+  domain \
   fun \
   gc \
   in_channel \

stdlib/domain.ml

@@ -296,6 +296,6 @@ let join { term_sync ; _ } =
   in
   match Mutex.protect term_sync.mut loop with
   | Ok x -> x
-  | Error ex -> raise ex
+  | Error ex -> Printexc.raise_with_backtrace ex (Printexc.get_raw_backtrace ())
 
 let recommended_domain_count = Raw.get_recommended_domain_count