Fix -fPIC for C sources

src/fpm/manifest/feature_collection.f90

@@ -15,7 +15,8 @@ module fpm_manifest_feature_collection
                           id_unknown, id_gcc, id_f95, id_caf, &
                           id_intel_classic_nix, id_intel_classic_mac, id_intel_classic_windows, &
                           id_intel_llvm_nix, id_intel_llvm_windows, id_intel_llvm_unknown, &
-                          id_pgi, id_nvhpc, id_nag, id_flang, id_lahey, id_lfortran, id_all
+                          id_pgi, id_nvhpc, id_nag, id_flang, id_lahey, id_lfortran, id_all, &
+                          get_debug_compile_flags, get_release_compile_flags
     use fpm_strings, only: string_t, lower, operator(==), split, str
     use tomlf, only: toml_table, toml_array, toml_key, toml_stat
     use fpm_toml, only: get_value, len, serializable_t, set_value, set_string, set_list, add_table, &
@@ -921,8 +922,24 @@ function default_variant(name, compiler_id, os_type, flags) result(feature)
         feature%name = name
         feature%platform%compiler = compiler_id
         feature%platform%os_type = os_type
-        feature%flags = flags
         feature%default = .true.  ! These are built-in features
+
+        ! FFLAGS
+        ! The argument flags is no more needed but it is kept for backward compatibility
+        ! flags are hard-coded in default_release/debug_feature
+        ! It might better to be pulled from default compile flags defined in fpm_compiler.F90
+        ! TODO: Validate this change
+        call get_debug_compile_flags(compiler_id, feature%flags)
+
+        ! test if release is requested
+        if (name == "release") call get_release_compile_flags(compiler_id, feature%flags)
+
+        ! CFLAGS
+        ! Equivalent function of get_debug/release_compile_flags must be implemented in fpm_compiler.F90
+        ! Hot fix: hard-coded c_flags=-fPIC (especially needed for shared library) 
+        ! TODO: Validate this change
+        feature%c_flags = "-fPIC"
+
     end function default_variant