Merge branch 'fix/cmake_uninitialized_vars' into 'master'

fix(build): do not rely on uninitialized  variables and variables set in parent scope

See merge request espressif/esp-idf!39615

components/esp_coex/CMakeLists.txt

@@ -1,5 +1,7 @@
 idf_build_get_property(idf_target IDF_TARGET)
 
+set(srcs "")
+
 if(${idf_target} STREQUAL "linux")
     return() # This component is not supported by the POSIX/Linux simulator
 endif()

components/esp_common/project_include.cmake

@@ -1,6 +1,8 @@
 #
 # Warn if the toolchain version doesn't match
 #
+idf_build_get_property(target IDF_TARGET)
+
 if(NOT (${target} STREQUAL "linux" OR CMAKE_C_COMPILER_ID MATCHES "Clang"))
     execute_process(
         COMMAND ${CMAKE_C_COMPILER} -dumpmachine

components/lwip/CMakeLists.txt

@@ -1,4 +1,5 @@
 idf_build_get_property(target IDF_TARGET)
+set(srcs "")
 
 if(CONFIG_LWIP_ENABLE)
     if(NOT ${target} STREQUAL "linux")

components/newlib/CMakeLists.txt

@@ -66,6 +66,7 @@ else()
          "src/picolibc/open_memstream.c")
 endif()
 
+set(ldfragments "")
 list(APPEND ldfragments "src/newlib.lf" "src/system_libs.lf")
 
 if(CONFIG_SPIRAM_CACHE_WORKAROUND)

components/vfs/CMakeLists.txt

@@ -7,6 +7,8 @@ if(${target} STREQUAL "linux")
     return()
 endif()
 
+set(sources "")
+
 list(APPEND sources "vfs.c"
                     "vfs_eventfd.c"
                     "vfs_semihost.c"