[macos] add install name flags

Author: perazz

src/fpm_compiler.F90

@@ -105,6 +105,8 @@ module fpm_compiler
     procedure :: get_main_flags
     !> Get library export flags
     procedure :: get_export_flags    
+    !> Get library install name flags
+    procedure :: get_install_name_flags
     !> Compile a Fortran object
     procedure :: compile_fortran
     !> Compile a C object
@@ -1117,6 +1119,28 @@ function get_export_flags(self, target_dir, target_name) result(export_flags)
 
 end function get_export_flags
 
+!>
+!> Generate `install_name` flag for a shared library build on macOS
+!>
+function get_install_name_flags(self, target_dir, target_name) result(flags)
+    class(compiler_t), intent(in) :: self
+    character(len=*), intent(in) :: target_dir, target_name
+    character(len=:), allocatable :: flags
+
+    if (get_os_type() /= OS_MACOS) then
+        flags = ""
+        return
+    end if
+
+    ! Shared library basename (e.g., libfoo.dylib)
+    if (str_ends_with(target_name, ".dylib")) then
+        flags = " -Wl,-install_name,@rpath/" // target_name
+    else
+        flags = " -Wl,-install_name,@rpath/" // target_name // ".dylib"
+    end if
+
+end function get_install_name_flags
+
 !> Create new compiler instance
 subroutine new_compiler(self, fc, cc, cxx, echo, verbose)
     !> New instance of the compiler

src/fpm_targets.f90

@@ -1142,8 +1142,13 @@ subroutine resolve_target_linking(targets, model, library, error)
                     target%link_flags = target%link_flags // " " // &
                                         model%compiler%get_export_flags(target%output_dir,target%package_name)
 
+                    ! Add install_name flag (macOS only)
+                    target%link_flags = target%link_flags // " " // &
+                                        model%compiler%get_install_name_flags(target%output_dir, target%package_name)                    
+                    
                     ! Add global link flags (e.g., system-wide libraries)
-                    target%link_flags = target%link_flags // " " // global_link_flags                
+                    target%link_flags = target%link_flags // " " // global_link_flags     
+                            
 
                 case (FPM_TARGET_EXECUTABLE)