From 30ba4328e728d2d5e2981378557b1b688722404c Mon Sep 17 00:00:00 2001
From: Miodrag Milanovic <mmicko@gmail.com>
Date: Mon, 13 Jul 2026 15:26:00 +0200
Subject: [PATCH] Use system libs when available

---
 frontends/CMakeLists.txt       |  4 ++-
 frontends/slang/CMakeLists.txt |  1 -
 libs/CMakeLists.txt            | 55 +++++++++++++++++++++-------------
 libs/slang                     |  2 +-
 4 files changed, 39 insertions(+), 23 deletions(-)

diff --git a/frontends/CMakeLists.txt b/frontends/CMakeLists.txt
index 6e6eda488..983fa2fd9 100644
--- a/frontends/CMakeLists.txt
+++ b/frontends/CMakeLists.txt
@@ -6,6 +6,8 @@ add_subdirectory(json)
 add_subdirectory(liberty)
 add_subdirectory(rpc)
 add_subdirectory(rtlil)
-add_subdirectory(slang)
+if (NOT YOSYS_WITHOUT_SLANG)
+    add_subdirectory(slang)
+endif()
 add_subdirectory(verific)
 add_subdirectory(verilog)
diff --git a/frontends/slang/CMakeLists.txt b/frontends/slang/CMakeLists.txt
index dae714de9..83bf98573 100644
--- a/frontends/slang/CMakeLists.txt
+++ b/frontends/slang/CMakeLists.txt
@@ -35,5 +35,4 @@ yosys_frontend(slang
 		${CMAKE_CURRENT_BINARY_DIR}
 	LIBRARIES
 		$<${YOSYS_ENABLE_SLANG}:slang::slang>
-		fmt::fmt
 )
diff --git a/libs/CMakeLists.txt b/libs/CMakeLists.txt
index 5ea08ef9d..385425af2 100644
--- a/libs/CMakeLists.txt
+++ b/libs/CMakeLists.txt
@@ -12,28 +12,43 @@ block()
     include(FetchContent)
     set(FETCHCONTENT_FULLY_DISCONNECTED ON)
 
-    option(FMT_INSTALL OFF)
-    FetchContent_Declare(
-        fmt
-        EXCLUDE_FROM_ALL
-        SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/fmt
-    )
-    FetchContent_MakeAvailable(fmt)
+    find_package(fmt 12.2 QUIET)
+    if(fmt_FOUND)
+        set(SLANG_USE_SYSTEM_FMT ON)
+    else()
+        option(FMT_INSTALL OFF)
+        FetchContent_Declare(
+            fmt
+            EXCLUDE_FROM_ALL
+            SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/fmt
+        )
+        FetchContent_MakeAvailable(fmt)
+    endif()
 
-    FetchContent_Declare(
-        tomlplusplus
-        EXCLUDE_FROM_ALL
-        SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/tomlplusplus
-    )
-    FetchContent_MakeAvailable(tomlplusplus)
+    find_package(tomlplusplus 3.4 QUIET)
+    if(tomlplusplus_FOUND)
+        set(SLANG_USE_SYSTEM_TOMLPLUSPLUS ON)
+    else()
+        FetchContent_Declare(
+            tomlplusplus
+            EXCLUDE_FROM_ALL
+            SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/tomlplusplus
+        )
+        FetchContent_MakeAvailable(tomlplusplus)
+    endif()
 
-    FetchContent_Declare(
-        boost_regex
-        EXCLUDE_FROM_ALL
-        SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/boost_regex
-        SOURCE_SUBDIR _no_build_
-    )
-    FetchContent_MakeAvailable(boost_regex)
+    find_package(Boost 1.87.0 CONFIG QUIET)
+    if(Boost_FOUND)
+        set(SLANG_USE_SYSTEM_BOOST ON)
+    else()
+        FetchContent_Declare(
+            boost_regex
+            EXCLUDE_FROM_ALL
+            SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/boost_regex
+            SOURCE_SUBDIR _no_build_
+        )
+        FetchContent_MakeAvailable(boost_regex)
+    endif()
 
     if (NOT YOSYS_WITHOUT_SLANG)
         set(SLANG_USE_MIMALLOC OFF)
diff --git a/libs/slang b/libs/slang
index 617575096..8acc660a2 160000
--- a/libs/slang
+++ b/libs/slang
@@ -1 +1 @@
-Subproject commit 6175750969f17289695f94be5105f6006c82eb61
+Subproject commit 8acc660a20b70de48ecec1c7471863e6f4b3ae6f