From 955d85aa6707cb4ce67d79508ea51856a9113f80 Mon Sep 17 00:00:00 2001
From: Al Semjonovs <asemjonovs@google.com>
Date: Mon, 2 Oct 2023 11:55:05 -0600
Subject: [PATCH] libc: picolibc: Fix picolibc to allow third party CPP

Picolibc dependencies limit ability to use third party minimal
implementations of CPP when enablng PICOLIBC_USE_MODULE.

Signed-off-by: Al Semjonovs <asemjonovs@google.com>
---
 cmake/linker/ld/target_cpp.cmake | 8 +++++---
 lib/cpp/Kconfig                  | 7 ++++++-
 lib/libc/Kconfig                 | 2 +-
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/cmake/linker/ld/target_cpp.cmake b/cmake/linker/ld/target_cpp.cmake
index 057bb02bc6d..a6601347172 100644
--- a/cmake/linker/ld/target_cpp.cmake
+++ b/cmake/linker/ld/target_cpp.cmake
@@ -4,8 +4,10 @@
 
 macro(toolchain_ld_cpp)
 
-  zephyr_link_libraries(
-    -lstdc++
-  )
+  if(NOT CONFIG_EXTERNAL_MODULE_LIBCPP)
+    zephyr_link_libraries(
+      -lstdc++
+    )
+  endif()
 
 endmacro()
diff --git a/lib/cpp/Kconfig b/lib/cpp/Kconfig
index 52084fbe690..696df05102a 100644
--- a/lib/cpp/Kconfig
+++ b/lib/cpp/Kconfig
@@ -107,7 +107,12 @@ config ARCMWDT_LIBCPP
 config EXTERNAL_LIBCPP
 	bool "External C++ standard library"
 	help
-	  Build with an external/user-provided C++ standard library.
+	  Build and link with an external/user-provided C++ standard library.
+
+config EXTERNAL_MODULE_LIBCPP
+	bool "External C++ standard library module"
+	help
+	  Build an external/user-provided C++ standard library.
 
 endchoice # LIBCPP_IMPLEMENTATION
 
diff --git a/lib/libc/Kconfig b/lib/libc/Kconfig
index 7febf1574d4..3bb83af5b1e 100644
--- a/lib/libc/Kconfig
+++ b/lib/libc/Kconfig
@@ -36,7 +36,7 @@ config PICOLIBC_SUPPORTED
 	bool
 	depends on !NATIVE_APPLICATION
 	depends on ("$(TOOLCHAIN_HAS_PICOLIBC)" = "y") || (NATIVE_LIBRARY)
-	depends on !(CPP && ("$(TOOLCHAIN_HAS_PICOLIBC)" = "y"))
+	depends on !REQUIRES_FULL_LIBCPP || ("$(TOOLCHAIN_HAS_PICOLIBC)" = "y")
 	default y
 	select FULL_LIBC_SUPPORTED
 	help