cmake/sitl: use CheckLinkerFlag instead of GCC version check for --no-warn-rwx-segments

[sensei-hacker]

Summary

Replace the fragile GCC version check for --no-warn-rwx-segments in cmake/sitl.cmake with a proper CheckLinkerFlag capability probe.

Changes

• Remove CMAKE_COMPILER_IS_GNUCC + VERSION_LESS 12.0 heuristic
• Add include(CheckLinkerFlag) and check_linker_flag() probe
• The probe directly tests whether the linker accepts the flag, rather than guessing from the compiler version

check_linker_flag() has been available since CMake 3.18; SITL already requires CMake 3.22+, so there is no minimum version concern.

Testing

• Built SITL successfully after the change
• On this system the probe correctly detected that --no-warn-rwx-segments is not supported (ld < 2.39) and skipped the flag — build completed cleanly with no linker warnings or errors
• On systems with ld ≥ 2.39 the probe will pass and the flag will be applied as before

[qodo-code-review]

Review Summary by Qodo

Replace GCC version check with CheckLinkerFlag probe

✨ Enhancement

Walkthroughs

Description

• Replace GCC version heuristic with proper linker capability probe
• Use CMake's CheckLinkerFlag module for robust flag detection
• Directly test linker support instead of guessing from compiler version

Diagram

flowchart LR
  A["GCC version check<br/>CMAKE_COMPILER_IS_GNUCC"] -->|replaced| B["CheckLinkerFlag probe<br/>check_linker_flag()"]
  B -->|tests linker support| C["LINKER_SUPPORTS_NO_RWX_WARNING"]
  C -->|if true| D["Apply --no-warn-rwx-segments flag"]

Loading

File Changes

1. cmake/sitl.cmake ✨ Enhancement +3/-1

Replace version check with linker capability probe

• Removed fragile GCC version check (CMAKE_COMPILER_IS_GNUCC + VERSION_LESS 12.0)
• Added include(CheckLinkerFlag) module
• Replaced version heuristic with check_linker_flag() probe for --no-warn-rwx-segments
• Flag is now applied only when linker actually supports it

cmake/sitl.cmake

---

[qodo-code-review]

Code Review by Qodo

🐞 Bugs (2) 📘 Rule violations (0) 📎 Requirement gaps (0)

1. Breaks older CMake configs ☑ 🐞 Bug ⛯ Reliability

Description

cmake/sitl.cmake now unconditionally calls include(CheckLinkerFlag)/check_linker_flag(), but
the repository still allows CMake 3.13+. Configuring with CMake < 3.18 will fail while parsing
sitl.cmake, even when SITL is not enabled, because include(sitl) is unconditional.

Code

cmake/sitl.cmake[R67-68]

+    include(CheckLinkerFlag)
+    check_linker_flag(C "-Wl,--no-warn-rwx-segments" LINKER_SUPPORTS_NO_RWX_WARNING)

Evidence

The repo declares a minimum CMake version as low as 3.13 and always includes sitl.cmake, so any
newer CMake-module dependency used at file scope becomes a hard configure-time requirement for all
builds. The PR description itself states check_linker_flag() is only available since CMake 3.18,
which conflicts with the repo’s stated minimum.

CMakeLists.txt[1-1]
CMakeLists.txt[92-95]
cmake/sitl.cmake[61-69]

Agent prompt

The issue below was found during a code review. Follow the provided context and guidance below and implement a solution

## Issue description
`cmake/sitl.cmake` uses `include(CheckLinkerFlag)` / `check_linker_flag()`, but the repo’s declared minimum CMake version is 3.13. This can make configuration fail on older CMake versions because `sitl.cmake` is included unconditionally.
### Issue Context
Top-level `CMakeLists.txt` uses `cmake_minimum_required(VERSION 3.13...3.18)` and always `include(sitl)`, so anything executed at file scope in `cmake/sitl.cmake` must be compatible with the minimum supported CMake.
### Fix Focus Areas
- CMakeLists.txt[1-1]
- CMakeLists.txt[92-95]
- cmake/sitl.cmake[61-71]
### Suggested fix approaches
1) **Preferred (if acceptable):** bump minimum CMake to **>= 3.18**.
2) **Otherwise:** guard usage:
 - Check `if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.18)` (and/or `if(COMMAND check_linker_flag)` after `include(CheckLinkerFlag OPTIONAL)`) before calling it.
 - On older CMake, skip adding the flag or use a fallback heuristic.

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---

2. Probe runs on all builds ☑ 🐞 Bug ➹ Performance

Description

The new check_linker_flag() probe runs at configure time whenever sitl.cmake is included, even
for non-SITL builds where target_sitl() immediately returns. This adds unnecessary configure-time
work and, under the cross toolchain, try_compile is set to produce only static libraries, which is
a poor fit for validating linker options.

Code

cmake/sitl.cmake[R67-71]

+    include(CheckLinkerFlag)
+    check_linker_flag(C "-Wl,--no-warn-rwx-segments" LINKER_SUPPORTS_NO_RWX_WARNING)
+    if(LINKER_SUPPORTS_NO_RWX_WARNING)
       set(SITL_LINK_OPTIONS ${SITL_LINK_OPTIONS} "-Wl,--no-warn-rwx-segments")
   endif()

Evidence

sitl.cmake is included unconditionally by the top-level build. The linker-flag probe is executed
at file scope, but actual SITL targets are only created when TOOLCHAIN is host. For non-SITL
builds, the default toolchain is arm-none-eabi, which sets CMAKE_TRY_COMPILE_TARGET_TYPE to
STATIC_LIBRARY, making configure-time link-flag probing less appropriate than simply running it
only when building SITL.

CMakeLists.txt[13-23]
CMakeLists.txt[92-95]
cmake/sitl.cmake[61-71]
cmake/sitl.cmake[81-88]
cmake/arm-none-eabi.cmake[8-13]

Agent prompt

The issue below was found during a code review. Follow the provided context and guidance below and implement a solution

## Issue description
`check_linker_flag()` currently runs at file scope in `cmake/sitl.cmake`, so it executes during configuration for all builds (including non-SITL embedded builds) even though SITL targets aren’t generated unless `TOOLCHAIN` is `host`.
### Issue Context
- `CMakeLists.txt` unconditionally `include(sitl)`.
- `target_sitl()` returns early when not building with the host toolchain.
- The arm-none-eabi toolchain sets `CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY`, which is not ideal for link-option probing.
### Fix Focus Areas
- CMakeLists.txt[92-95]
- cmake/sitl.cmake[61-71]
- cmake/sitl.cmake[81-88]
### Suggested fix
Move or guard the probe so it only runs when building SITL with the host toolchain, e.g.:
- Wrap the probe with `if(SITL)` and/or `if(TOOLCHAIN STREQUAL "host")`, **or**
- Relocate the `include(CheckLinkerFlag)` + `check_linker_flag(...)` block into `function(target_sitl ...)` after the `if(NOT host STREQUAL TOOLCHAIN) return()` guard.

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---

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[github-actions]

Test firmware build ready — commit 36bb13d

Download firmware for PR #11383

223 targets built. Find your board's .hex file by name on that page (e.g. MATEKF405SE.hex). Files are individually downloadable — no GitHub login required.

Development build for testing only. Use Full Chip Erase when flashing.