build: remove sed usage in build system

`sed` is not available on all platforms, we cannot depend on that to
rewrite the module map.  As a temporary stop gap, write the file
statically and generate it at build time.  Eventually, this could be
replaced with a tool or CMake based text processing to generate the
content.  This repairs part of the build for Windows with bootstrapping.

Author: compnerd

SwiftCompilerSources/CMakeLists.txt

@@ -230,18 +230,25 @@ else()
 
   add_subdirectory(Sources)
 
-  # This is a hack to get correct dependencies from imported C++ headers:
-  # step 1: generate a dummy source file, which just includes all headers defined in include/swift/module.modulemap
-  add_custom_command(
-    OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/HeaderDependencies.cpp"
-    COMMAND
-        "sed"
-        -n -e "/header/!d" -e "s/.*header/#include/" -e "w ${CMAKE_CURRENT_BINARY_DIR}/HeaderDependencies.cpp"
-        "${CMAKE_CURRENT_SOURCE_DIR}/../include/swift/module.modulemap"
-    DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/../include/swift/module.modulemap"
-    COMMENT "Generate HeaderDependencies.cpp"
-)
-  
+  # TODO: generate this dynamically through the modulemap; this cannot use `sed`
+  # as that is not available on all paltforms (e.g. Windows).
+  file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/HeaderDependencies.cpp"
+       "\
+#include \"Basic/BridgedSwiftObject.h\" \
+#include \"Basic/BasicBridging.h\" \
+#include \"Basic/SourceLoc.h\" \
+\
+#include \"AST/ASTBridging.h\" \
+#include \"AST/DiagnosticEngine.h\" \
+#include \"AST/DiagnosticConsumer.h\" \
+\
+#include \"SIL/SILBridging.h\" \
+\
+#include \"SILOptimizer/OptimizerBridging.h\" \
+\
+#include \"Parse/RegexParserBridging.h\" \
+")
+
   # step 2: build a library containing that source file. This library depends on all the included header files.
   #         The swift modules can now depend on that target.
   #         Note that this library is unused, i.e. not linked to anything.