support clang reduced BMI compilation

Add an opt-in Clang 23 policy that generates reduced BMIs and compiles module objects directly from source so both jobs can run in parallel. Add module coverage and update the stdmodules_deps fixture for Clang's P1857R3 enforcement.

1 files changed, 4 insertions, 1 deletions

diff --git a/tests/projects/c++/modules/test_base.lua b/tests/projects/c++/modules/test_base.lua
index 372229695..ecb468197 100644
--- a/tests/projects/c++/modules/test_base.lua
+++ b/tests/projects/c++/modules/test_base.lua
@@ -103,6 +103,9 @@ function build_tests(toolchain_name, opt)
     local policies = "--policies=build.c++.modules.std:" .. (opt.stdmodule and "y" or "n")
     policies = policies .. ",build.c++.modules.fallbackscanner:" .. (opt.fallbackscanner and "y" or "n")
     policies = policies .. ",build.c++.modules.two_phases:" .. (two_phases and "y" or "n")
+    if opt.precompile_reduced_bmi ~= nil then
+        policies = policies .. ",build.c++.modules.clang.precompile_reduced_bmi:" .. (opt.precompile_reduced_bmi and "y" or "n")
+    end
 
     local platform = " "
     if opt.platform then
@@ -127,7 +130,7 @@ function build_tests(toolchain_name, opt)
     os.exec("xmake clean -a")
     os.exec("xmake f" .. platform .. "--toolchain=" .. toolchain_name .. runtimes .. "-c --yes " .. policies .. flags)
     if opt.build then
-        opt.build()
+        opt.build(table.join(opt, {toolchain = toolchain_name, two_phases = two_phases}))
     else
         _build(opt.check_outdata)
     end