Temporarily workaround CMake dependencies bug

Workaround a CMake bug in order to make sure that libraries are rebuilt
when their dependencies change.

Author: bnbarham

Sources/CMakeLists.txt

@@ -6,6 +6,28 @@
 # See http://swift.org/LICENSE.txt for license information
 # See http://swift.org/CONTRIBUTORS.txt for Swift project authors
 
+# cmake generation for Swift adds an order only dependency, which matches how C-family languages
+# works. In that case, however, ninja (and presumably other generators) will rebuild on header
+# changes. That's not the case for Swift, and thus if A -> B, A is not being rebuilt when the
+# ABI/API of B changes.
+#
+# For now workaround this by touching a file whenever B is rebuilt and then compiling that file as
+# part of A. Ideally this file would be generated by each of the targets, but that dependency didn't
+# seem to be being tracked.
+function(add_forced_dependency TARGET DEPENDENCY)
+  target_link_libraries(${TARGET} PUBLIC
+    ${DEPENDENCY}
+  )
+
+  add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/forced-${DEPENDENCY}-dep.swift
+    COMMAND ${CMAKE_COMMAND} -E touch ${CMAKE_CURRENT_BINARY_DIR}/forced-${DEPENDENCY}-dep.swift
+    DEPENDS ${DEPENDENCY}
+  )
+  target_sources(${TARGET} PRIVATE
+    ${CMAKE_CURRENT_BINARY_DIR}/forced-${DEPENDENCY}-dep.swift
+  )
+endfunction()
+
 add_subdirectory(SwiftBasicFormat)
 add_subdirectory(SwiftSyntax)
 add_subdirectory(SwiftDiagnostics)

Sources/IDEUtils/CMakeLists.txt

@@ -12,7 +12,9 @@ add_library(IDEUtils STATIC
   SyntaxClassifier.swift
 )
 
-target_link_libraries(IDEUtils PUBLIC
+# TODO: Change to `target_link_libraries(IDEUtils PUBLIC
+#       when cmake is fixed
+add_forced_dependency(IDEUtils
   SwiftSyntax)
 
 set_property(GLOBAL APPEND PROPERTY SWIFTSYNTAX_EXPORTS IDEUtils)

Sources/SwiftBasicFormat/CMakeLists.txt

@@ -13,7 +13,9 @@ add_library(SwiftBasicFormat STATIC
   Utils.swift
 )
 
-target_link_libraries(SwiftBasicFormat PUBLIC
+# TODO: Change to `target_link_libraries(SwiftBasicFormat PUBLIC
+#       when cmake is fixed
+add_forced_dependency(SwiftBasicFormat
   SwiftSyntax)
 
 set_property(GLOBAL APPEND PROPERTY SWIFTSYNTAX_EXPORTS SwiftBasicFormat)

Sources/SwiftCompilerSupport/CMakeLists.txt

@@ -10,7 +10,9 @@ add_library(SwiftCompilerSupport STATIC
   ConsistencyCheck.swift
 )
 
-target_link_libraries(SwiftCompilerSupport PUBLIC
+# TODO: Change to `target_link_libraries(SwiftCompilerSupport PUBLIC
+#       when cmake is fixed
+add_forced_dependency(SwiftCompilerSupport
   SwiftSyntax
   SwiftDiagnostics
   SwiftParser

Sources/SwiftDiagnostics/CMakeLists.txt

@@ -14,7 +14,9 @@ add_library(SwiftDiagnostics STATIC
   Note.swift
 )
 
-target_link_libraries(SwiftDiagnostics PUBLIC
+# TODO: Change to `target_link_libraries(SwiftDiagnostics PUBLIC
+#       when cmake is fixed
+add_forced_dependency(SwiftDiagnostics
   SwiftSyntax)
 
 set_property(GLOBAL APPEND PROPERTY SWIFTSYNTAX_EXPORTS SwiftDiagnostics)

Sources/SwiftOperators/CMakeLists.txt

@@ -19,7 +19,9 @@ add_library(SwiftOperators STATIC
   SyntaxSynthesis.swift
 )
 
-target_link_libraries(SwiftOperators PUBLIC
+# TODO: Change to `target_link_libraries(SwiftOperators PUBLIC
+#       when cmake is fixed
+add_forced_dependency(SwiftOperators
   SwiftSyntax
   SwiftDiagnostics
   SwiftParser)

Sources/SwiftParser/CMakeLists.txt

@@ -36,7 +36,9 @@ add_library(SwiftParser STATIC
   gyb_generated/DeclarationModifier.swift
   gyb_generated/TypeAttribute.swift)
 
-target_link_libraries(SwiftParser PUBLIC
+# TODO: Change to `target_link_libraries(SwiftParser PUBLIC
+#       when cmake is fixed
+add_forced_dependency(SwiftParser
   SwiftSyntax
   SwiftDiagnostics)
 
@@ -47,6 +49,15 @@ set_target_properties(SwiftParser PROPERTIES
   INTERFACE_INCLUDE_DIRECTORIES
   "${CMAKE_Swift_MODULE_DIRECTORY}")
 
+#file(TOUCH ${CMAKE_CURRENT_BINARY_DIR}/SwiftParser-complete.swift)
+#add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/SwiftParser-complete.swift
+#  COMMAND ${CMAKE_COMMAND} -E touch ${CMAKE_CURRENT_BINARY_DIR}/SwiftParser-complete.swift
+#  DEPENDS SwiftParser
+#)
+#set_target_properties(SwiftParser
+#  PROPERTIES FORCE_DEP_PATH ${CMAKE_CURRENT_BINARY_DIR}/SwiftParser-complete.swift
+#)
+
 install(TARGETS SwiftParser
   EXPORT SwiftSyntaxTargets
   ARCHIVE DESTINATION lib

Sources/SwiftParserDiagnostics/CMakeLists.txt

@@ -15,7 +15,9 @@ add_library(SwiftParserDiagnostics STATIC
   SyntaxExtensions.swift
   Utils.swift)
 
-target_link_libraries(SwiftParserDiagnostics PUBLIC
+# TODO: Change to `target_link_libraries(SwiftParserDiagnostics PUBLIC
+#       when cmake is fixed
+add_forced_dependency(SwiftParserDiagnostics
   SwiftBasicFormat
   SwiftDiagnostics
   SwiftParser

Sources/SwiftSyntaxBuilder/CMakeLists.txt

@@ -23,7 +23,9 @@ add_library(SwiftSyntaxBuilder STATIC
   gyb_generated/SyntaxExpressibleByStringInterpolationConformances.swift
 )
 
-target_link_libraries(SwiftSyntaxBuilder PUBLIC
+# TODO: Change to `target_link_libraries(SwiftSyntaxBuilder PUBLIC
+#       when cmake is fixed
+add_forced_dependency(SwiftSyntaxBuilder
   SwiftBasicFormat
   SwiftParser
   SwiftParserDiagnostics

Sources/_SwiftSyntaxMacros/CMakeLists.txt

@@ -17,7 +17,9 @@ add_library(_SwiftSyntaxMacros STATIC
   Syntax+MacroEvaluation.swift
 )
 
-target_link_libraries(_SwiftSyntaxMacros PUBLIC
+# TODO: Change to `target_link_libraries(_SwiftSyntaxMacros PUBLIC
+#       when cmake is fixed
+add_forced_dependency(_SwiftSyntaxMacros
   SwiftParser
   SwiftSyntaxBuilder
   )