Example 5: fix parallel .mod race by separate Fortran module dirs per target (#460)

Example 5: fix parallel .mod race by separating module dirs

* Set Fortran module output dirs per mod_good and mod_bad and add to include paths
* docs(cmake): add brief comment on isolating .mod output per target
* fix indentation and align target names for Example 5

---------

Co-authored-by: Jack Atkinson <[email protected]>

Author: zka26

examples/5_Looping/CMakeLists.txt

@@ -36,6 +36,14 @@ target_link_libraries(simplenet_infer_fortran_bad
                       PRIVATE FTorch::ftorch)
 target_sources(simplenet_infer_fortran_bad
                PRIVATE bad/fortran_ml_mod.f90)
+# Both targets define the same Fortran module name (ml_mod). Write .mod files
+# to per-target directories to avoid collisions during parallel builds
+set_target_properties(simplenet_infer_fortran_bad PROPERTIES
+                      Fortran_MODULE_DIRECTORY
+                      ${CMAKE_CURRENT_BINARY_DIR}/mod_bad
+)
+target_include_directories(simplenet_infer_fortran_bad PRIVATE
+                           ${CMAKE_CURRENT_BINARY_DIR}/mod_bad)
 
 # Fortran example - good
 add_executable(simplenet_infer_fortran_good
@@ -44,3 +52,10 @@ target_link_libraries(simplenet_infer_fortran_good
                       PRIVATE FTorch::ftorch)
 target_sources(simplenet_infer_fortran_good
                PRIVATE good/fortran_ml_mod.f90)
+# Same purpose as above: isolate this target's .mod output for parallel builds
+set_target_properties(simplenet_infer_fortran_good PROPERTIES
+                      Fortran_MODULE_DIRECTORY
+                      ${CMAKE_CURRENT_BINARY_DIR}/mod_good
+)
+target_include_directories(simplenet_infer_fortran_good PRIVATE
+                           ${CMAKE_CURRENT_BINARY_DIR}/mod_good)