cmake: build the "all" examples source list dynamically

To allow building conditional examples, and to simplify by avoiding
cmake-version dependent code.

Follow-up to fe5225b5eaf3a1a0ce149023d38a9922a114798b #18209
Cherry-picked from #18909
Closes #18911

diff --git a/docs/examples/CMakeLists.txt b/docs/examples/CMakeLists.txt
index bc0f3ce359b8630d3390ee18221ea8abb5538d44..d86494c8708bd30214051d7939ad072213b53288 100644 (file)
--- a/docs/examples/CMakeLists.txt
+++ b/docs/examples/CMakeLists.txt
@@ -28,15 +28,14 @@ add_custom_target(curl-examples)
 curl_transform_makefile_inc("Makefile.inc" "${CMAKE_CURRENT_BINARY_DIR}/Makefile.inc.cmake")
 include("${CMAKE_CURRENT_BINARY_DIR}/Makefile.inc.cmake")
 
+set(_all_src "")
 set(_all_canary "")
 set(_all "all")
 foreach(_target IN LISTS check_PROGRAMS _all)  # keep '_all' last
   set(_target_name "curl-example-${_target}")
   if(_target STREQUAL "all")
     if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.12)
-      set(_examples_c "${check_PROGRAMS}")
-      list(TRANSFORM _examples_c APPEND ".c")
-      add_library(${_target_name} OBJECT EXCLUDE_FROM_ALL ${_examples_c})
+      add_library(${_target_name} OBJECT EXCLUDE_FROM_ALL ${_all_src})
       if(CMAKE_C_COMPILER_ID STREQUAL "MSVC")  # MSVC but exclude clang-cl
         # CMake generates a static library for the OBJECT target. Silence these 'lib.exe' warnings:
         # warning LNK4006: main already defined in ....obj; second definition ignored
@@ -49,16 +48,13 @@ foreach(_target IN LISTS check_PROGRAMS _all)  # keep '_all' last
         endif()
       endif()
     else()
-      set(_examples_c "")
-      foreach(_src IN LISTS check_PROGRAMS)
-        list(APPEND _examples_c "${_src}.c")
-      endforeach()
-      add_library(${_target_name} STATIC EXCLUDE_FROM_ALL ${_examples_c})
+      add_library(${_target_name} STATIC EXCLUDE_FROM_ALL ${_all_src})
     endif()
     add_custom_target(curl-examples-build)  # Special target to compile all tests quickly and build a single test to probe linkage
     add_dependencies(curl-examples-build ${_target_name} ${_all_canary})  # Include a full build of a single test
   else()
     set(_all_canary ${_target_name})  # Save the last test for the curl-examples-build target
+    list(APPEND _all_src "${_target}.c")
     add_executable(${_target_name} EXCLUDE_FROM_ALL "${_target}.c")
     add_dependencies(curl-examples ${_target_name})
   endif()