[still undefined symbols with full LTO; test with thin LTO]

Author: kinke

.github/workflows/main.yml

@@ -134,8 +134,8 @@ jobs:
             # `RT_CFLAGS=-m32` needed to make 64-bit clang-cl output 32-bit code for druntime integration tests
             extra_cmake_flags: >-
               -DRT_CFLAGS=-m32
-              "-DD_COMPILER_FLAGS=-O -flto=full -defaultlib=phobos2-ldc-lto,druntime-ldc-lto"
-              -DEXTRA_CXXFLAGS=-flto=full
+              "-DD_COMPILER_FLAGS=-O -flto=thin -defaultlib=phobos2-ldc-lto,druntime-ldc-lto"
+              -DEXTRA_CXXFLAGS=-flto=thin
             with_pgo: true
 
     name: ${{ matrix.job_name }}