Generate build/.gitignore (#528)

- git-specific, but not git-dependent but is it better if managed directly by fpm
- no .gitignore generated by subcommand new

Author: urbanjost

src/fpm.f90

@@ -5,7 +5,7 @@ module fpm
                       fpm_run_settings, fpm_install_settings, fpm_test_settings
 use fpm_dependency, only : new_dependency_tree
 use fpm_environment, only: run, get_env
-use fpm_filesystem, only: is_dir, join_path, number_of_rows, list_files, exists, basename
+use fpm_filesystem, only: is_dir, join_path, number_of_rows, list_files, exists, basename, filewrite, mkdir
 use fpm_model, only: fpm_model_t, srcfile_t, show_model, &
                     FPM_SCOPE_UNKNOWN, FPM_SCOPE_LIB, FPM_SCOPE_DEP, &
                     FPM_SCOPE_APP, FPM_SCOPE_EXAMPLE, FPM_SCOPE_TEST
@@ -58,6 +58,11 @@ subroutine build_model(model, settings, package, error)
     call model%deps%add(package, error)
     if (allocated(error)) return
 
+    ! build/ directory should now exist
+    if (.not.exists("build/.gitignore")) then
+      call filewrite(join_path("build", ".gitignore"),["*"])
+    end if
+
     if(settings%compiler.eq.'')then
         model%fortran_compiler = 'gfortran'
     else

src/fpm/cmd/new.f90

@@ -98,9 +98,6 @@ subroutine cmd_new(settings)
     ! like realpath() or getcwd().
     bname=basename(settings%name)
 
-    ! create NAME/.gitignore file
-    call warnwrite(join_path(settings%name, '.gitignore'), ['build/*'])
-
     littlefile=[character(len=80) :: '# '//bname, 'My cool new project!']
 
     ! create NAME/README.md

src/fpm/cmd/update.f90

@@ -2,7 +2,7 @@ module fpm_cmd_update
   use fpm_command_line, only : fpm_update_settings
   use fpm_dependency, only : dependency_tree_t, new_dependency_tree
   use fpm_error, only : error_t, fpm_stop
-  use fpm_filesystem, only : exists, mkdir, join_path, delete_file
+  use fpm_filesystem, only : exists, mkdir, join_path, delete_file, filewrite
   use fpm_manifest, only : package_config_t, get_package_data
   implicit none
   private
@@ -26,6 +26,7 @@ subroutine cmd_update(settings)
 
     if (.not.exists("build")) then
       call mkdir("build")
+      call filewrite(join_path("build", ".gitignore"),["*"])
     end if
 
     cache = join_path("build", "cache.toml")

src/fpm_command_line.f90

@@ -938,14 +938,11 @@ subroutine set_help()
     '   o runs the command "git init" in that directory                     ', &
     '   o populates the directory with the default project directories      ', &
     '   o adds sample Fortran source files                                  ', &
-    '   o adds a ".gitignore" file for ignoring the build/ directory        ', &
-    '     (where fpm-generated output will be placed)                       ', &
     '                                                                       ', &
     ' The default file structure (that will be automatically scanned) is    ', &
     '                                                                       ', &
     '     NAME/                                                             ', &
     '       fpm.toml                                                        ', &
-    '       .gitignore                                                      ', &
     '       src/                                                            ', &
     '           NAME.f90                                                    ', &
     '       app/                                                            ', &
@@ -1006,8 +1003,8 @@ subroutine set_help()
     '              depend extensively on non-default build options.         ', &
     '                                                                       ', &
     ' --bare       A minimal manifest file ("fpm.toml") is created and      ', &
-    '              a ".gitignore" and "README.md" file is created but no    ', &
-    '              directories or sample Fortran is generated.              ', &
+    '              "README.md" file is created but no directories or        ', &
+    '              sample Fortran are generated.                            ', &
     '                                                                       ', &
     ' --help       print this help and exit                                 ', &
     ' --version    print program version information and exit               ', &