Change #248119

Comments

cmake: adjust defaults for target platforms not supporting shared libs

If CMake reports the target platform not supporting shared libs, turn
`BUILD_SHARED_LIBS` off by default. CMake 3.30+ fails with an error
when trying to create a `SHARED` target for such platforms. Earlier
versions used a workaround that may or may not have worked in practice.

Ref: https://cmake.org/cmake/help/v3.30/policy/CMP0164.html

Seen this with a build setting `-DCMAKE_SYSTEM_NAME=Generic`, e.g.
AmigaOS.

Note this may introduce incompatibility for "Generic" targets, which
support shared libs. If that's the case, set `BUILD_SHARED_LIBS=ON`
manually.

Also drop AmigaOS-specific logic handled automatically after this patch.

Ref: https://cmake.org/cmake/help/v3.7/command/get_property.html
Ref: https://cmake.org/cmake/help/v3.7/prop_gbl/TARGET_SUPPORTS_SHARED_LIBS.html

Closes #19420

Changed files

• CMakeLists.txt
• docs/INSTALL-CMAKE.md