build core and glsl modules in the same slang-bootstrap invocation (shader-slang#6341)

Closes shader-slang#6339

Author: expipiplus1

source/slang-core-module/CMakeLists.txt

@@ -100,15 +100,37 @@ set(core_module_generated_header_dir ${CMAKE_CURRENT_BINARY_DIR})
 set(core_module_generated_header
     ${core_module_generated_header_dir}/slang-core-module-generated.h
 )
+set(glsl_module_generated_header_dir
+    ${CMAKE_CURRENT_BINARY_DIR}/../slang-glsl-module
+)
+set(glsl_module_generated_header
+    ${glsl_module_generated_header_dir}/slang-glsl-module-generated.h
+)
+
+# Propagate to parent directory scope, so they're visible to
+# slang-glsl-module/CMakeLists.txt
+set(glsl_module_generated_header_dir
+    ${glsl_module_generated_header_dir}
+    PARENT_SCOPE
+)
+set(glsl_module_generated_header ${glsl_module_generated_header} PARENT_SCOPE)
 
 add_custom_command(
     OUTPUT ${core_module_generated_header} ${glsl_module_generated_header}
     COMMAND
         slang-bootstrap -archive-type riff-lz4 -save-core-module-bin-source
-        ${core_module_generated_header}
+        ${core_module_generated_header} -save-glsl-module-bin-source
+        ${glsl_module_generated_header}
     DEPENDS slang-bootstrap
     VERBATIM
 )
+# Add a target so that we can depend on the above step when we create the glsl
+# module
+add_custom_target(
+    generate_core_module_headers
+    DEPENDS ${core_module_generated_header} ${glsl_module_generated_header}
+)
+set_target_properties(generate_core_module_headers PROPERTIES FOLDER generated)
 
 set(core_module_common_args
     .

source/slang-glsl-module/CMakeLists.txt

@@ -1,19 +1,15 @@
 #
 # Generate an embeddable glsl module
 #
-set(glsl_module_generated_header_dir ${CMAKE_CURRENT_BINARY_DIR})
-set(glsl_module_generated_header
-    ${glsl_module_generated_header_dir}/slang-glsl-module-generated.h
-)
-add_custom_command(
-    OUTPUT ${glsl_module_generated_header}
-    COMMAND
-        slang-bootstrap -archive-type riff-lz4 -save-glsl-module-bin-source
-        ${glsl_module_generated_header}
-    DEPENDS slang-bootstrap
-    VERBATIM
-)
 
+# This header is generated in the same call to slang-bootstrap that generates
+# the core module embed, which can be found in
+# ../slang-core-module/CMakeLists.txt
+# The target to look for is generate_core_module_headers
+
+# CMake doesn't allow creating an implicit dependency across directory scopes,
+# see https://cmake.org/cmake/help/v3.31/prop_sf/GENERATED.html. Because of
+# this we add the explicit REQUIRES
 slang_add_target(
     .
     MODULE
@@ -23,6 +19,7 @@ slang_add_target(
     EXPLICIT_SOURCE
         ./slang-embedded-glsl-module.cpp
         ${glsl_module_generated_header}
+    REQUIRES generate_core_module_headers
     EXCLUDE_FROM_ALL
     EXTRA_COMPILE_DEFINITIONS_PRIVATE SLANG_SHARED_LIBRARY_TOOL
     EXPORT_SET_NAME SlangTargets