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S
Suess
Associate II
August 15, 2026
Question

STM32CubeMX2 Generated Code Throws Error When Treating Warnings As Errors

  • August 15, 2026
  • 0 replies
  • 8 views

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After generating a CMAKE project using STM32CubeMX2 v1.1.1 followed by setting compiler options to “treat warnings as errors” (-Werror) and enable strict standards-conformance (-Wpedantic) in the root CMakeLists.txt file, I am errors in, mx_def.h.

 

Though this post shows the workaround:

  • What is the recommended C Standard that STM32C5 project should follow?
  • If the generated code stated “gnu11” but yet uses “gnu23”, shouldn’t the generator use the latter instead (see solution)?
  • And, what are the dangers of doing so?

 

Error Message:

error: ISO C restricts enumerator values to range of 'int' before C23

 

Full Error message:

[build] C:/PathTo/ProjectName/source/App/generated/hal/mx_def.h:32:38: error: ISO C restricts enumerator values to range of 'int' before C23 [-Werror=pedantic]
[build]    32 |   SYSTEM_OK                        = 0xEAEAEAEAU,        /* System initialization successfully       */
[build]       |                                      ^~~~~~~~~~~
[build] C:/PathTo/ProjectName/source/App/generated/hal/mx_def.h:33:38: error: ISO C restricts enumerator values to range of 'int' before C23 [-Werror=pedantic]
[build]    33 |   SYSTEM_PRESYSTEM_ERROR           = 0xF5F5F5F5U,        /* Error during System pre-initialization   */
[build]       |        

 

Screen Shot:

Reproduce Issue
 

To recreate this error:

  1. Open your generated project’s root “CMakeLists.txt” (generated by CubeMX2)
  2. Add the following to the target_compile_options(..) section:
  3. Clean and Compile Project
  4. The above errors will appear

Path: (root)/CMakeLists.txt

target_compile_options(${CMAKE_PROJECT_NAME} PUBLIC
  # Add additional compiler flags here

  # Warnings for C code:
  -Wpedantic              # Enable strict standards-conformance warnings (cleaner portable C code).
  -Wno-strict-prototypes  # Ignore pre-ANSI C style of '(void)'
  -Werror                 # Treats all warnings as errors
)

 
The Cause of the issue
 

The generated mx_def.h  enum, system_status_t uses values too large for C11 standard (i.e. greater than signed int), however they are allowed in C23 and GNU23 C Standard.

 

The Solution

  1. Open your generated file, “cmake/flags.cmake”
  2. Locate the “target_compile_options(“ that defines, “-std=gnu11”
  3. Update this value to “-std=gnu23”
  4. Clean project and recompile.

Path: cmake/flags.cmake

# file-format: 1.0.0
if(CMAKE_BUILD_TYPE STREQUAL "debug_GCC_STM32C562RET6")
  set_target_properties(${CMAKE_PROJECT_NAME} PROPERTIES SUFFIX ".elf")
  target_compile_options(${CMAKE_PROJECT_NAME} PUBLIC ${CPU_FLAGS})
  target_compile_options(${CMAKE_PROJECT_NAME} PUBLIC "SHELL:-g3 -O0 -fdata-sections -ffunction-sections -std=gnu11 -Wall -fstack-usage --specs=nano.specs --specs=nosys.specs -Werror=implicit-function-declaration ${CC_SECURE}")
  target_include_directories(${CMAKE_PROJECT_NAME} PUBLIC

 

Recommendation

The generated project’s Target Compiler Option “-std” specification should match the code that is generated.

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