Merge branch 'feature/clang_toolchain_compat' into 'master'

Build system: minimal changes for clang compatibility

See merge request espressif/esp-idf!15168

CMakeLists.txt

@@ -20,7 +20,9 @@ if(NOT BOOTLOADER_BUILD)
 
     if(CONFIG_COMPILER_OPTIMIZATION_SIZE)
         list(APPEND compile_options "-Os")
-        list(APPEND compile_options "-freorder-blocks")
+        if(CMAKE_C_COMPILER_ID MATCHES "GNU")
+            list(APPEND compile_options "-freorder-blocks")
+        endif()
     elseif(CONFIG_COMPILER_OPTIMIZATION_DEFAULT)
         list(APPEND compile_options "-Og")
     elseif(CONFIG_COMPILER_OPTIMIZATION_NONE)
@@ -33,7 +35,9 @@ else()  # BOOTLOADER_BUILD
 
     if(CONFIG_BOOTLOADER_COMPILER_OPTIMIZATION_SIZE)
         list(APPEND compile_options "-Os")
-        list(APPEND compile_options "-freorder-blocks")
+        if(CMAKE_C_COMPILER_ID MATCHES "GNU")
+            list(APPEND compile_options "-freorder-blocks")
+        endif()
     elseif(CONFIG_BOOTLOADER_COMPILER_OPTIMIZATION_DEBUG)
         list(APPEND compile_options "-Og")
     elseif(CONFIG_BOOTLOADER_COMPILER_OPTIMIZATION_NONE)
@@ -74,6 +78,48 @@ if(CONFIG_COMPILER_DISABLE_GCC8_WARNINGS)
                                 "-Wno-int-in-bool-context")
 endif()
 
+if(CMAKE_C_COMPILER_ID MATCHES "GNU")
+    list(APPEND c_compile_options "-Wno-old-style-declaration")
+endif()
+
+# Clang finds some warnings in IDF code which GCC doesn't.
+# All these warnings should be fixed before Clang is presented
+# as a toolchain choice for users.
+if(CMAKE_C_COMPILER_ID MATCHES "Clang")
+    # Clang checks Doxygen comments for being in sync with function prototype.
+    # There are some inconsistencies, especially in ROM headers.
+    list(APPEND compile_options "-Wno-documentation")
+    # GCC allows repeated typedefs when the source and target types are the same.
+    # Clang doesn't allow this. This occurs in many components due to forward
+    # declarations.
+    list(APPEND compile_options "-Wno-typedef-redefinition")
+    # This issue is seemingly related to newlib's char type functions.
+    # Fix is not clear yet.
+    list(APPEND compile_options "-Wno-char-subscripts")
+    # Clang seems to notice format string issues which GCC doesn't.
+    list(APPEND compile_options "-Wno-format-security")
+    # Logic bug in essl component
+    list(APPEND compile_options "-Wno-tautological-overlap-compare")
+    # Some pointer checks in mDNS component check addresses which can't be NULL
+    list(APPEND compile_options "-Wno-tautological-pointer-compare")
+    # Similar to the above, in tcp_transport
+    list(APPEND compile_options "-Wno-pointer-bool-conversion")
+    # mbedTLS md5.c triggers this warning in md5_test_buf (false positive)
+    list(APPEND compile_options "-Wno-string-concatenation")
+    # multiple cases of implict convertions between unrelated enum types
+    list(APPEND compile_options "-Wno-enum-conversion")
+    # When IRAM_ATTR is specified both in function declaration and definition,
+    # it produces different section names, since section names include __COUNTER__.
+    # Occurs in multiple places.
+    list(APPEND compile_options "-Wno-section")
+    # Multiple cases of attributes unknown to clang, for example
+    # __attribute__((optimize("-O3")))
+    list(APPEND compile_options "-Wno-unknown-attributes")
+    # Clang also produces many -Wunused-function warnings which GCC doesn't.
+    # However these aren't treated as errors.
+endif()
+# More warnings may exist in unit tests and example projects.
+
 if(CONFIG_COMPILER_WARN_WRITE_STRINGS)
     list(APPEND compile_options "-Wwrite-strings")
 endif()
@@ -118,7 +164,15 @@ list(APPEND link_options "-fno-lto")
 # Placing jump tables in flash would cause issues with code that required
 # to be placed in IRAM
 list(APPEND compile_options "-fno-jump-tables")
-list(APPEND compile_options "-fno-tree-switch-conversion")
+if(CMAKE_C_COMPILER_ID MATCHES "GNU")
+    # This flag is GCC-specific.
+    # Not clear yet if some other flag should be used for Clang.
+    list(APPEND compile_options "-fno-tree-switch-conversion")
+endif()
+
+if(CMAKE_C_COMPILER_ID MATCHES "LLVM")
+    list(APPEND compile_options "-fno-use-cxa-atexit")
+endif()
 
 idf_build_set_property(COMPILE_OPTIONS "${compile_options}" APPEND)
 idf_build_set_property(C_COMPILE_OPTIONS "${c_compile_options}" APPEND)

components/cbor/CMakeLists.txt

@@ -13,3 +13,8 @@ idf_component_register(SRCS "tinycbor/src/cborencoder_close_container_checked.c"
 
 # for open_memstream.c
 set_source_files_properties(tinycbor/src/open_memstream.c PROPERTIES COMPILE_DEFINITIONS "__linux__")
+
+# workaround for the fact that we are passing -ffreestanding to Clang
+if(CMAKE_C_COMPILER_ID MATCHES "Clang")
+    target_compile_options(${COMPONENT_LIB} PRIVATE "-U __STDC_HOSTED__")
+endif()

components/console/CMakeLists.txt

@@ -6,3 +6,7 @@ idf_component_register(SRCS "commands.c"
                     INCLUDE_DIRS "."
                     REQUIRES vfs
                     PRIV_REQUIRES driver)
+
+if(CMAKE_C_COMPILER_ID MATCHES "GNU")
+    set_source_files_properties(argtable3/argtable3.c PROPERTIES COMPILE_FLAGS -Wno-clobbered)
+endif()

components/console/argtable3/argtable3.c

@@ -30,8 +30,6 @@
 
 #include "argtable3.h"
 
-#pragma GCC diagnostic ignored "-Wclobbered"
-
 /*******************************************************************************
  * This file is part of the argtable3 library.
  *

components/console/component.mk

@@ -1,2 +1,4 @@
 COMPONENT_ADD_INCLUDEDIRS := .
 COMPONENT_SRCDIRS := linenoise argtable3 .
+
+argtable3/argtable3.o: CFLAGS += -Wno-clobbered

components/esp_common/project_include.cmake

@@ -1,8 +1,12 @@
 #
 # Warn if the toolchain version doesn't match
 #
-if(NOT ${target} STREQUAL "linux")
+if(NOT (${target} STREQUAL "linux" OR CMAKE_C_COMPILER_ID MATCHES "Clang"))
     get_expected_ctng_version(expected_toolchain expected_gcc)
     gcc_version_check("${expected_gcc}")
     crosstool_version_check("${expected_toolchain}")
 endif()
+
+if(NOT ${target} STREQUAL "linux" AND CMAKE_C_COMPILER_ID MATCHES "Clang")
+    message(WARNING "Building ESP-IDF with clang is an experimental feature and is not yet officially supported.")
+endif()

components/esp_system/panic.c

@@ -399,7 +399,7 @@ void IRAM_ATTR __attribute__((noreturn, no_sanitize_undefined)) panic_abort(cons
 #endif
 #endif
 
-    *((int *) 0) = 0; // NOLINT(clang-analyzer-core.NullDereference) should be an invalid operation on targets
+    *((volatile int *) 0) = 0; // NOLINT(clang-analyzer-core.NullDereference) should be an invalid operation on targets
     while (1);
 }
 

components/newlib/syscalls.c

@@ -94,8 +94,10 @@ int _fstat_r (struct _reent *r, int fd, struct stat *st)
  * doesn't have the same signature as the original function.
  * Disable type mismatch warnings for this reason.
  */
+#if defined(__GNUC__) && !defined(__clang__)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wattribute-alias"
+#endif
 
 int _open_r(struct _reent *r, const char * path, int flags, int mode)
     __attribute__((weak,alias("syscall_not_implemented")));
@@ -133,7 +135,9 @@ int _kill_r(struct _reent *r, int pid, int sig)
 void _exit(int __status)
     __attribute__((alias("syscall_not_implemented_aborts")));
 
+#if defined(__GNUC__) && !defined(__clang__)
 #pragma GCC diagnostic pop
+#endif
 
 /* Similar to syscall_not_implemented, but not taking struct _reent argument */
 int system(const char* str)

components/spi_flash/CMakeLists.txt

@@ -55,5 +55,9 @@ idf_component_register(SRCS "${srcs}"
                     LDFRAGMENTS linker.lf)
 
 # Avoid cache miss by unexpected inlineing when built by -Os
-set_source_files_properties(${cache_srcs} PROPERTIES COMPILE_FLAGS
+set_source_files_properties(${cache_srcs} PROPERTIES COMPILE_FLAGS "-fno-inline-functions")
-    "-fno-inline-functions -fno-inline-small-functions -fno-inline-functions-called-once")
+if(CMAKE_C_COMPILER_ID MATCHES "GNU")
+    # These flags are GCC specific
+    set_property(SOURCE ${cache_srcs} APPEND_STRING PROPERTY COMPILE_FLAGS
+        " -fno-inline-small-functions -fno-inline-functions-called-once")
+endif()

components/spi_flash/include/spi_flash_chip_generic.h

@@ -408,4 +408,4 @@ esp_err_t spi_flash_chip_generic_suspend_cmd_conf(esp_flash_t *chip);
 esp_err_t spi_flash_chip_generic_read_unique_id_none(esp_flash_t *chip, uint64_t* flash_unique_id);
 
 /// Default timeout configuration used by most chips
-const flash_chip_op_timeout_t spi_flash_chip_generic_timeout;
+extern const flash_chip_op_timeout_t spi_flash_chip_generic_timeout;

components/spiffs/CMakeLists.txt

@@ -10,4 +10,6 @@ idf_component_register(SRCS "esp_spiffs.c"
                     REQUIRES spi_flash
                     PRIV_REQUIRES bootloader_support esptool_py)
 
-set_source_files_properties(spiffs/src/spiffs_nucleus.c PROPERTIES COMPILE_FLAGS -Wno-stringop-truncation)
+if(CMAKE_C_COMPILER_ID MATCHES "GNU")
+    set_source_files_properties(spiffs/src/spiffs_nucleus.c PROPERTIES COMPILE_FLAGS -Wno-stringop-truncation)
+endif()

tools/ci/test_build_system_cmake.sh

@@ -446,12 +446,6 @@ function run_tests()
     mv CMakeLists.bak CMakeLists.txt
     assert_built ${APP_BINS} ${BOOTLOADER_BINS} ${PARTITION_BIN}
 
-    print_status "Can find toolchain file in component directory"
-    clean_build_dir
-    mv ${IDF_PATH}/tools/cmake/toolchain-esp32.cmake ${IDF_PATH}/components/esp32/
-    (idf.py reconfigure > /dev/null && grep "${IDF_PATH}/components/esp32/toolchain-esp32.cmake" build/CMakeCache.txt) || failure  "Failed to find toolchain file in component directory"
-    mv ${IDF_PATH}/components/esp32/toolchain-esp32.cmake ${IDF_PATH}/tools/cmake/
-
     print_status "Setting EXTRA_COMPONENT_DIRS works"
     clean_build_dir
     (idf.py reconfigure | grep "$PWD/main") || failure  "Failed to verify original `main` directory"

tools/cmake/build.cmake

@@ -107,8 +107,7 @@ function(__build_set_default_build_specifications)
                                     # go into the final binary so have no impact on size
                                     "-ggdb")
 
-    list(APPEND c_compile_options   "-std=gnu99"
+    list(APPEND c_compile_options   "-std=gnu99")
-                                    "-Wno-old-style-declaration")
 
     list(APPEND cxx_compile_options "-std=gnu++11")
 

tools/cmake/targets.cmake

@@ -47,23 +47,37 @@ endfunction()
 #
 macro(__target_set_toolchain)
     idf_build_get_property(idf_path IDF_PATH)
+
+    # See if Clang toolchain should be used
+    set(env_idf_toolchain $ENV{IDF_TOOLCHAIN})
+    if(NOT env_idf_toolchain)
+        # IDF_TOOLCHAIN not set in environment, see if it is set in cache
+        if(IDF_TOOLCHAIN)
+            set(env_idf_toolchain ${IDF_TOOLCHAIN})
+        else()
+            set(env_idf_toolchain gcc)
+        endif()
+    else()
+        # IDF_TOOLCHAIN set both in environment and in cache, must be the same
+        if(NOT ${IDF_TOOLCHAIN} STREQUAL ${env_idf_toolchain})
+            message(FATAL_ERROR "IDF_TOOLCHAIN in CMake cache does not match "
+                    "IDF_TOOLCHAIN environment variable. To change the toolchain, clear "
+                    "the build directory and sdkconfig file, and build the project again")
+        endif()
+    endif()
+
+    # Finally, set IDF_TOOLCHAIN in cache
+    set(IDF_TOOLCHAIN ${env_idf_toolchain} CACHE STRING "IDF Build Toolchain Type")
+
+    if(${env_idf_toolchain} STREQUAL "clang")
+        set(toolchain_type "clang-")
+    endif()
+
     # First try to load the toolchain file from the tools/cmake/directory of IDF
-    set(toolchain_file_global ${idf_path}/tools/cmake/toolchain-${IDF_TARGET}.cmake)
+    set(toolchain_file_global ${idf_path}/tools/cmake/toolchain-${toolchain_type}${IDF_TARGET}.cmake)
     if(EXISTS ${toolchain_file_global})
         set(CMAKE_TOOLCHAIN_FILE ${toolchain_file_global})
     else()
-        __component_get_target(component_target ${IDF_TARGET})
+        message(FATAL_ERROR "Toolchain file ${toolchain_file_global} not found")
-        if(NOT component_target)
-            message(FATAL_ERROR "Unable to resolve '${IDF_TARGET}' for setting toolchain file.")
-        endif()
-        get_property(component_dir TARGET ${component_target} PROPERTY COMPONENT_DIR)
-        # Try to load the toolchain file from the directory of IDF_TARGET component
-        set(toolchain_file_component ${component_dir}/toolchain-${IDF_TARGET}.cmake)
-        if(EXISTS ${toolchain_file_component})
-            set(CMAKE_TOOLCHAIN_FILE ${toolchain_file_component})
-        else()
-            message(FATAL_ERROR "Toolchain file toolchain-${IDF_TARGET}.cmake not found,"
-                    "checked ${toolchain_file_global} and ${toolchain_file_component}")
-        endif()
     endif()
 endmacro()

tools/cmake/toolchain-clang-esp32.cmake

@@ -0,0 +1,16 @@
+set(CMAKE_SYSTEM_NAME Generic)
+
+set(CMAKE_C_COMPILER clang)
+set(CMAKE_CXX_COMPILER clang++)
+set(CMAKE_ASM_COMPILER clang)
+
+set(CMAKE_AR xtensa-esp32-elf-ar)
+set(CMAKE_RANLIB xtensa-esp32-elf-gcc-ranlib)
+set(CMAKE_OBJDUMP xtensa-esp32-elf-objdump)
+
+# -freestanding is a hack to force Clang to use its own stdatomic.h,
+# without falling back to the (incompatible) GCC stdatomic.h
+# https://github.com/espressif/llvm-project/blob/d9341b81/clang/lib/Headers/stdatomic.h#L13-L18
+set(CMAKE_C_FLAGS "--target=xtensa -mcpu=esp32 -ffreestanding" CACHE STRING "C Compiler Base Flags")
+set(CMAKE_CXX_FLAGS "--target=xtensa -mcpu=esp32 -ffreestanding" CACHE STRING "C++ Compiler Base Flags")
+set(CMAKE_ASM_FLAGS "--target=xtensa -mcpu=esp32" CACHE STRING "Assembler Base Flags")

tools/cmake/toolchain-clang-esp32s2.cmake

@@ -0,0 +1,16 @@
+set(CMAKE_SYSTEM_NAME Generic)
+
+set(CMAKE_C_COMPILER clang)
+set(CMAKE_CXX_COMPILER clang++)
+set(CMAKE_ASM_COMPILER clang)
+
+set(CMAKE_AR xtensa-esp32-elf-ar)
+set(CMAKE_RANLIB xtensa-esp32-elf-gcc-ranlib)
+set(CMAKE_OBJDUMP xtensa-esp32-elf-objdump)
+
+# -freestanding is a hack to force Clang to use its own stdatomic.h,
+# without falling back to the (incompatible) GCC stdatomic.h
+# https://github.com/espressif/llvm-project/blob/d9341b81/clang/lib/Headers/stdatomic.h#L13-L18
+set(CMAKE_C_FLAGS "--target=xtensa -mcpu=esp32s2 -ffreestanding" CACHE STRING "C Compiler Base Flags")
+set(CMAKE_CXX_FLAGS "--target=xtensa -mcpu=esp32s2 -ffreestanding" CACHE STRING "C++ Compiler Base Flags")
+set(CMAKE_ASM_FLAGS "--target=xtensa -mcpu=esp32s2" CACHE STRING "Assembler Base Flags")