From c6b5bac1bdb03c4086e5d044c0857d4b2f0dc1ba Mon Sep 17 00:00:00 2001
From: Eric Miotto <emiotto@apple.com>
Date: Tue, 21 Oct 2025 09:38:57 -0700
Subject: [PATCH 1/3] Runtimes: in macOS smoke test point to module cache from
 compiler build

This will ensure we are not racing with other runs running on the same
builders.

Addresses rdar://163122836
---
 CMakeLists.txt                                 |  9 ++++++---
 Runtimes/Core/CMakeLists.txt                   |  3 ++-
 Runtimes/Overlay/CMakeLists.txt                |  3 ++-
 Runtimes/Supplemental/CMakeLists.txt           | 18 ++++++++++++------
 .../Differentiation/CMakeLists.txt             |  3 ++-
 .../Supplemental/Distributed/CMakeLists.txt    |  3 ++-
 .../Supplemental/Observation/CMakeLists.txt    |  3 ++-
 Runtimes/Supplemental/Runtime/CMakeLists.txt   |  3 ++-
 .../StringProcessing/CMakeLists.txt            |  3 ++-
 .../Synchronization/CMakeLists.txt             |  3 ++-
 Runtimes/Supplemental/Volatile/CMakeLists.txt  |  3 ++-
 11 files changed, 36 insertions(+), 18 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9eb5c044bf96f..ed8c2938836cb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1673,7 +1673,8 @@ if(SWIFT_ENABLE_NEW_RUNTIME_BUILD)
           -DCMAKE_COLOR_DIAGNOSTICS:BOOLEAN=${CMAKE_COLOR_DIAGNOSTICS}
           -DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}
           -DSwiftCore_INSTALL_NESTED_SUBDIR=YES
-          -DSwiftCore_ENABLE_CONCURRENCY=${build_concurrency})
+          -DSwiftCore_ENABLE_CONCURRENCY=${build_concurrency}
+          -DSwiftCore_MODULE_CACHE_PATH=${SWIFT_MODULE_CACHE_PATH})
       if(NOT ${CMAKE_CROSSCOMPILING})
         add_dependencies("${stdlib_target}-core" swift-frontend)
       endif()
@@ -1700,7 +1701,8 @@ if(SWIFT_ENABLE_NEW_RUNTIME_BUILD)
           -DCMAKE_CXX_COMPILER_TARGET:STRING=${stdlib_target_triple}
           -DCMAKE_COLOR_DIAGNOSTICS:BOOLEAN=${CMAKE_COLOR_DIAGNOSTICS}
           -DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}
-          -DCMAKE_FIND_PACKAGE_PREFER_CONFIG=TRUE)
+          -DCMAKE_FIND_PACKAGE_PREFER_CONFIG=TRUE
+          -DSwiftOverlay_MODULE_CACHE_PATH=${SWIFT_MODULE_CACHE_PATH})
 
       ExternalProject_Add("${stdlib_target}-Supplemental"
         SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/Runtimes/Supplemental"
@@ -1724,7 +1726,8 @@ if(SWIFT_ENABLE_NEW_RUNTIME_BUILD)
           -DCMAKE_CXX_COMPILER_TARGET:STRING=${stdlib_target_triple}
           -DCMAKE_COLOR_DIAGNOSTICS:BOOLEAN=${CMAKE_COLOR_DIAGNOSTICS}
           -DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}
-          -DCMAKE_FIND_PACKAGE_PREFER_CONFIG=TRUE)
+          -DCMAKE_FIND_PACKAGE_PREFER_CONFIG=TRUE
+          -DSwiftSupplemental_MODULE_CACHE_PATH=${SWIFT_MODULE_CACHE_PATH})
     endforeach()
   endforeach()
 endif()
diff --git a/Runtimes/Core/CMakeLists.txt b/Runtimes/Core/CMakeLists.txt
index a6428b6b425ab..f8281b4350227 100644
--- a/Runtimes/Core/CMakeLists.txt
+++ b/Runtimes/Core/CMakeLists.txt
@@ -194,7 +194,8 @@ add_compile_options(
   "$<$<AND:$<NOT:$<BOOL:${SwiftCore_ENABLE_OBJC_INTEROP}>>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -disable-objc-interop>"
   "$<$<AND:$<PLATFORM_ID:Windows>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xcc -Xclang -Xcc -fbuiltin-headers-in-system-modules>"
   "$<$<AND:$<BOOL:${SwiftCore_ENABLE_LIBRARY_EVOLUTION}>,$<COMPILE_LANGUAGE:Swift>>:-enable-library-evolution>"
-  "$<$<AND:$<BOOL:${SwiftCore_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>")
+  "$<$<AND:$<BOOL:${SwiftCore_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>"
+  "$<$<AND:$<BOOL:${SwiftCore_MODULE_CACHE_PATH}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-module-cache-path ${SwiftCore_MODULE_CACHE_PATH}>")
 
 include(ExperimentalFeatures)
 
diff --git a/Runtimes/Overlay/CMakeLists.txt b/Runtimes/Overlay/CMakeLists.txt
index 61afeb8f6459d..367981340d51d 100644
--- a/Runtimes/Overlay/CMakeLists.txt
+++ b/Runtimes/Overlay/CMakeLists.txt
@@ -73,7 +73,8 @@ add_compile_options(
   "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -enforce-exclusivity=unchecked>"
   "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -target-min-inlining-version -Xfrontend min>"
   "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_LIBRARY_EVOLUTION}>,$<COMPILE_LANGUAGE:Swift>>:-enable-library-evolution>"
-  "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>")
+  "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>"
+  "$<$<AND:$<BOOL:${${PROJECT_NAME}_MODULE_CACHE_PATH}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-module-cache-path ${${PROJECT_NAME}_MODULE_CACHE_PATH}>")
 
 include(ExperimentalFeatures)
 
diff --git a/Runtimes/Supplemental/CMakeLists.txt b/Runtimes/Supplemental/CMakeLists.txt
index 0b64b98c7c7e1..b3eb4b551d6ec 100644
--- a/Runtimes/Supplemental/CMakeLists.txt
+++ b/Runtimes/Supplemental/CMakeLists.txt
@@ -55,7 +55,8 @@ if(SwiftRuntime_ENABLE_stringprocessing)
     # To ensure incremental builds work as expected
     BUILD_ALWAYS 1
     CMAKE_ARGS
-      ${COMMON_OPTIONS})
+      ${COMMON_OPTIONS}
+      -DSwiftStringProcessing_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH})
 endif()
 
 # Synchronization
@@ -68,7 +69,8 @@ if(SwiftRuntime_ENABLE_synchronization)
     # To ensure incremental builds work as expected
     BUILD_ALWAYS 1
     CMAKE_ARGS
-      ${COMMON_OPTIONS})
+      ${COMMON_OPTIONS}
+      -DSwiftSynchronization_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH})
 endif()
 
 # Distributed
@@ -81,7 +83,8 @@ if(SwiftRuntime_ENABLE_distributed)
     # To ensure incremental builds work as expected
     BUILD_ALWAYS 1
     CMAKE_ARGS
-      ${COMMON_OPTIONS})
+      ${COMMON_OPTIONS}
+      -DSwiftDistributed_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH})
 endif()
 
 
@@ -95,7 +98,8 @@ if(SwiftRuntime_ENABLE_differentiation)
     # To ensure incremental builds work as expected
     BUILD_ALWAYS 1
     CMAKE_ARGS
-      ${COMMON_OPTIONS})
+      ${COMMON_OPTIONS}
+      -DSwiftDifferentiation_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH})
 endif()
 
 # Observation
@@ -108,7 +112,8 @@ if(SwiftRuntime_ENABLE_observation)
     # To ensure incremental builds work as expected
     BUILD_ALWAYS 1
     CMAKE_ARGS
-      ${COMMON_OPTIONS})
+      ${COMMON_OPTIONS}
+      -DSwiftObservation_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH})
 endif()
 
 # Runtime
@@ -121,5 +126,6 @@ if(SwiftRuntime_ENABLE_runtime)
     # To ensure incremental builds work as expected
     BUILD_ALWAYS 1
     CMAKE_ARGS
-      ${COMMON_OPTIONS})
+      ${COMMON_OPTIONS}
+      -DSwiftRuntime_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH})
 endif()
diff --git a/Runtimes/Supplemental/Differentiation/CMakeLists.txt b/Runtimes/Supplemental/Differentiation/CMakeLists.txt
index 3e0b42124aeff..f021e6df914b1 100644
--- a/Runtimes/Supplemental/Differentiation/CMakeLists.txt
+++ b/Runtimes/Supplemental/Differentiation/CMakeLists.txt
@@ -75,7 +75,8 @@ add_compile_options(
   "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-enable-experimental-feature MemberImportVisibility>"
   "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -enforce-exclusivity=unchecked>"
   "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -target-min-inlining-version -Xfrontend min>"
-  $<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_LIBRARY_EVOLUTION}>,$<COMPILE_LANGUAGE:Swift>>:-enable-library-evolution>)
+  $<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_LIBRARY_EVOLUTION}>,$<COMPILE_LANGUAGE:Swift>>:-enable-library-evolution>
+  "$<$<AND:$<BOOL:${${PROJECT_NAME}_MODULE_CACHE_PATH}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-module-cache-path ${${PROJECT_NAME}_MODULE_CACHE_PATH}>")
 
 # LNK4049: symbol 'symbol' defined in 'filename.obj' is imported
 # LNK4286: symbol 'symbol' defined in 'filename_1.obj' is imported by 'filename_2.obj'
diff --git a/Runtimes/Supplemental/Distributed/CMakeLists.txt b/Runtimes/Supplemental/Distributed/CMakeLists.txt
index a802147d72c7e..e35140e9662e5 100644
--- a/Runtimes/Supplemental/Distributed/CMakeLists.txt
+++ b/Runtimes/Supplemental/Distributed/CMakeLists.txt
@@ -82,7 +82,8 @@ add_compile_options(
   "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -enable-lexical-lifetimes=false>"
   "$<$<COMPILE_LANGUAGE:Swift>:-warn-implicit-overrides>"
   "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_LIBRARY_EVOLUTION}>,$<COMPILE_LANGUAGE:Swift>>:-enable-library-evolution>"
-  "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>")
+  "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>"
+  "$<$<AND:$<BOOL:${${PROJECT_NAME}_MODULE_CACHE_PATH}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-module-cache-path ${${PROJECT_NAME}_MODULE_CACHE_PATH}>")
 
 # LNK4049: symbol 'symbol' defined in 'filename.obj' is imported
 # LNK4286: symbol 'symbol' defined in 'filename_1.obj' is imported by 'filename_2.obj'
diff --git a/Runtimes/Supplemental/Observation/CMakeLists.txt b/Runtimes/Supplemental/Observation/CMakeLists.txt
index 98ce40a292f5e..444f7ef8953c4 100644
--- a/Runtimes/Supplemental/Observation/CMakeLists.txt
+++ b/Runtimes/Supplemental/Observation/CMakeLists.txt
@@ -80,7 +80,8 @@ add_compile_options(
   "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -enable-lexical-lifetimes=false>"
   "$<$<COMPILE_LANGUAGE:Swift>:-warn-implicit-overrides>"
   "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_LIBRARY_EVOLUTION}>,$<COMPILE_LANGUAGE:Swift>>:-enable-library-evolution>"
-  "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>")
+  "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>"
+  "$<$<AND:$<BOOL:${${PROJECT_NAME}_MODULE_CACHE_PATH}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-module-cache-path ${${PROJECT_NAME}_MODULE_CACHE_PATH}>")
 
 # LNK4049: symbol 'symbol' defined in 'filename.obj' is imported
 # LNK4286: symbol 'symbol' defined in 'filename_1.obj' is imported by 'filename_2.obj'
diff --git a/Runtimes/Supplemental/Runtime/CMakeLists.txt b/Runtimes/Supplemental/Runtime/CMakeLists.txt
index 099fa4945bea2..1d03c15b7181d 100644
--- a/Runtimes/Supplemental/Runtime/CMakeLists.txt
+++ b/Runtimes/Supplemental/Runtime/CMakeLists.txt
@@ -89,7 +89,8 @@ add_compile_options(
   "$<$<COMPILE_LANGUAGE:Swift>:-cxx-interoperability-mode=default>"
   "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -experimental-spi-only-imports>"
   "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_LIBRARY_EVOLUTION}>,$<COMPILE_LANGUAGE:Swift>>:-enable-library-evolution>"
-  "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>")
+  "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>"
+  "$<$<AND:$<BOOL:${${PROJECT_NAME}_MODULE_CACHE_PATH}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-module-cache-path ${${PROJECT_NAME}_MODULE_CACHE_PATH}>")
 
 # LNK4049: symbol 'symbol' defined in 'filename.obj' is imported
 # LNK4286: symbol 'symbol' defined in 'filename_1.obj' is imported by 'filename_2.obj'
diff --git a/Runtimes/Supplemental/StringProcessing/CMakeLists.txt b/Runtimes/Supplemental/StringProcessing/CMakeLists.txt
index 709ba16918411..837ff1a76b9b7 100644
--- a/Runtimes/Supplemental/StringProcessing/CMakeLists.txt
+++ b/Runtimes/Supplemental/StringProcessing/CMakeLists.txt
@@ -57,7 +57,8 @@ add_compile_options(
   "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -disable-implicit-string-processing-module-import>"
   "$<$<COMPILE_LANGUAGE:Swift>:-warn-implicit-overrides>"
   "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_LIBRARY_EVOLUTION}>,$<COMPILE_LANGUAGE:Swift>>:-enable-library-evolution>"
-  "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>")
+  "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>"
+  "$<$<AND:$<BOOL:${${PROJECT_NAME}_MODULE_CACHE_PATH}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-module-cache-path ${${PROJECT_NAME}_MODULE_CACHE_PATH}>")
 
 # LNK4049: symbol 'symbol' defined in 'filename.obj' is imported
 # LNK4286: symbol 'symbol' defined in 'filename_1.obj' is imported by 'filename_2.obj'
diff --git a/Runtimes/Supplemental/Synchronization/CMakeLists.txt b/Runtimes/Supplemental/Synchronization/CMakeLists.txt
index 2ab0500c53d94..e28b156205fba 100644
--- a/Runtimes/Supplemental/Synchronization/CMakeLists.txt
+++ b/Runtimes/Supplemental/Synchronization/CMakeLists.txt
@@ -93,7 +93,8 @@ add_compile_options(
   "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xfrontend -enable-lexical-lifetimes=false>"
   "$<$<COMPILE_LANGUAGE:Swift>:-warn-implicit-overrides>"
   "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_LIBRARY_EVOLUTION}>,$<COMPILE_LANGUAGE:Swift>>:-enable-library-evolution>"
-  "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>")
+  "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>"
+  "$<$<AND:$<BOOL:${${PROJECT_NAME}_MODULE_CACHE_PATH}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-module-cache-path ${${PROJECT_NAME}_MODULE_CACHE_PATH}>")
 
 # LNK4049: symbol 'symbol' defined in 'filename.obj' is imported
 # LNK4286: symbol 'symbol' defined in 'filename_1.obj' is imported by 'filename_2.obj'
diff --git a/Runtimes/Supplemental/Volatile/CMakeLists.txt b/Runtimes/Supplemental/Volatile/CMakeLists.txt
index ad8fc2428852a..d97a5c38f3dd0 100644
--- a/Runtimes/Supplemental/Volatile/CMakeLists.txt
+++ b/Runtimes/Supplemental/Volatile/CMakeLists.txt
@@ -68,7 +68,8 @@ add_compile_options(
   $<$<COMPILE_LANGUAGE:Swift>:-nostdlibimport>
   $<$<COMPILE_LANGUAGE:Swift>:-strict-memory-safety>
   "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_LIBRARY_EVOLUTION}>,$<COMPILE_LANGUAGE:Swift>>:-enable-library-evolution>"
-  "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>")
+  "$<$<AND:$<BOOL:${${PROJECT_NAME}_ENABLE_PRESPECIALIZATION}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-Xfrontend -prespecialize-generic-metadata>"
+  "$<$<AND:$<BOOL:${${PROJECT_NAME}_MODULE_CACHE_PATH}>,$<COMPILE_LANGUAGE:Swift>>:SHELL:-module-cache-path ${${PROJECT_NAME}_MODULE_CACHE_PATH}>")
 
 # LNK4049: symbol 'symbol' defined in 'filename.obj' is imported
 # LNK4286: symbol 'symbol' defined in 'filename_1.obj' is imported by 'filename_2.obj'

From fe772792b2b459aa32f4daafa18eba26f664b0ee Mon Sep 17 00:00:00 2001
From: Eric Miotto <emiotto@apple.com>
Date: Tue, 21 Oct 2025 11:01:48 -0700
Subject: [PATCH 2/3] Attempt to use separate caches for Core, Overlay and
 Supplemental:wq

---
 CMakeLists.txt | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ed8c2938836cb..ff0ba86469e39 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1674,7 +1674,7 @@ if(SWIFT_ENABLE_NEW_RUNTIME_BUILD)
           -DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}
           -DSwiftCore_INSTALL_NESTED_SUBDIR=YES
           -DSwiftCore_ENABLE_CONCURRENCY=${build_concurrency}
-          -DSwiftCore_MODULE_CACHE_PATH=${SWIFT_MODULE_CACHE_PATH})
+          -DSwiftCore_MODULE_CACHE_PATH=${SWIFT_MODULE_CACHE_PATH}-runtimes-core)
       if(NOT ${CMAKE_CROSSCOMPILING})
         add_dependencies("${stdlib_target}-core" swift-frontend)
       endif()
@@ -1702,7 +1702,7 @@ if(SWIFT_ENABLE_NEW_RUNTIME_BUILD)
           -DCMAKE_COLOR_DIAGNOSTICS:BOOLEAN=${CMAKE_COLOR_DIAGNOSTICS}
           -DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}
           -DCMAKE_FIND_PACKAGE_PREFER_CONFIG=TRUE
-          -DSwiftOverlay_MODULE_CACHE_PATH=${SWIFT_MODULE_CACHE_PATH})
+          -DSwiftOverlay_MODULE_CACHE_PATH=${SWIFT_MODULE_CACHE_PATH}-runtimes-overlay)
 
       ExternalProject_Add("${stdlib_target}-Supplemental"
         SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/Runtimes/Supplemental"
@@ -1727,7 +1727,7 @@ if(SWIFT_ENABLE_NEW_RUNTIME_BUILD)
           -DCMAKE_COLOR_DIAGNOSTICS:BOOLEAN=${CMAKE_COLOR_DIAGNOSTICS}
           -DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}
           -DCMAKE_FIND_PACKAGE_PREFER_CONFIG=TRUE
-          -DSwiftSupplemental_MODULE_CACHE_PATH=${SWIFT_MODULE_CACHE_PATH})
+          -DSwiftSupplemental_MODULE_CACHE_PATH=${SWIFT_MODULE_CACHE_PATH}-runtimes-supplemental)
     endforeach()
   endforeach()
 endif()

From f90359671b9b8704fd0a9e2d0380cdd1dcf2e6b7 Mon Sep 17 00:00:00 2001
From: Eric Miotto <emiotto@apple.com>
Date: Tue, 21 Oct 2025 12:08:53 -0700
Subject: [PATCH 3/3] Attempt to use separate caches for each Supplemental
 library

---
 Runtimes/Supplemental/CMakeLists.txt | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/Runtimes/Supplemental/CMakeLists.txt b/Runtimes/Supplemental/CMakeLists.txt
index b3eb4b551d6ec..8bdfffbbf5391 100644
--- a/Runtimes/Supplemental/CMakeLists.txt
+++ b/Runtimes/Supplemental/CMakeLists.txt
@@ -56,7 +56,7 @@ if(SwiftRuntime_ENABLE_stringprocessing)
     BUILD_ALWAYS 1
     CMAKE_ARGS
       ${COMMON_OPTIONS}
-      -DSwiftStringProcessing_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH})
+      -DSwiftStringProcessing_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH}-stringprocessing)
 endif()
 
 # Synchronization
@@ -70,7 +70,7 @@ if(SwiftRuntime_ENABLE_synchronization)
     BUILD_ALWAYS 1
     CMAKE_ARGS
       ${COMMON_OPTIONS}
-      -DSwiftSynchronization_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH})
+      -DSwiftSynchronization_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH}-synchronization)
 endif()
 
 # Distributed
@@ -84,7 +84,7 @@ if(SwiftRuntime_ENABLE_distributed)
     BUILD_ALWAYS 1
     CMAKE_ARGS
       ${COMMON_OPTIONS}
-      -DSwiftDistributed_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH})
+      -DSwiftDistributed_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH}-distributed)
 endif()
 
 
@@ -99,7 +99,7 @@ if(SwiftRuntime_ENABLE_differentiation)
     BUILD_ALWAYS 1
     CMAKE_ARGS
       ${COMMON_OPTIONS}
-      -DSwiftDifferentiation_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH})
+      -DSwiftDifferentiation_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH}-differentiation)
 endif()
 
 # Observation
@@ -113,7 +113,7 @@ if(SwiftRuntime_ENABLE_observation)
     BUILD_ALWAYS 1
     CMAKE_ARGS
       ${COMMON_OPTIONS}
-      -DSwiftObservation_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH})
+      -DSwiftObservation_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH}-observation)
 endif()
 
 # Runtime
@@ -127,5 +127,5 @@ if(SwiftRuntime_ENABLE_runtime)
     BUILD_ALWAYS 1
     CMAKE_ARGS
       ${COMMON_OPTIONS}
-      -DSwiftRuntime_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH})
+      -DSwiftRuntime_MODULE_CACHE_PATH=${SwiftSupplemental_MODULE_CACHE_PATH}-runtime)
 endif()