wrap: Implement special wrap modes for use by packagers

Special wrap modes:
  nofallback: Don't download wraps for dependency() fallbacks
  nodownload: Don't download wraps for all subproject() calls

Subprojects are used for two purposes:
1. To download and build dependencies by using .wrap files if they
   are not provided by the system. This is usually expressed via
   dependency(..., fallback: ...).
2. To download and build 'copylibs' which are meant to be used by
   copying into your project. This is always done with an explicit
   subproject() call.

--wrap-mode=nofallback will never do (1)
--wrap-mode=nodownload will do neither (1) nor (2)

If you are building from a release tarball, you should be able to
safely use 'nodownload' since upstream is expected to ship all
required sources with the tarball.

If you are building from a git repository, you will want to use
'nofallback' so that any 'copylib' wraps will be download as
subprojects.

Note that these options do not affect subprojects that are git
submodules since those are only usable in git repositories, and you
almost always want to download them.

1 files changed, 9 insertions, 1 deletions

diff --git a/mesonbuild/wrap/wrap.py b/mesonbuild/wrap/wrap.py
index ad2e3e4..fcacc16 100644
--- a/mesonbuild/wrap/wrap.py
+++ b/mesonbuild/wrap/wrap.py
@@ -18,6 +18,7 @@ import urllib.request, os, hashlib, shutil
 import subprocess
 import sys
 from pathlib import Path
+from . import WrapMode
 
 try:
     import ssl
@@ -94,7 +95,8 @@ class PackageDefinition:
         return 'patch_url' in self.values
 
 class Resolver:
-    def __init__(self, subdir_root):
+    def __init__(self, subdir_root, wrap_mode=WrapMode(1)):
+        self.wrap_mode = wrap_mode
         self.subdir_root = subdir_root
         self.cachedir = os.path.join(self.subdir_root, 'packagecache')
 
@@ -120,6 +122,12 @@ class Resolver:
         if self.resolve_git_submodule(dirname):
             return packagename
 
+        # Don't download subproject data based on wrap file if requested.
+        # Git submodules are ok (see above)!
+        if self.wrap_mode is WrapMode.nodownload:
+            m = 'Automatic wrap-based subproject downloading is disabled'
+            raise RuntimeError(m)
+
         # Check if there's a .wrap file for this subproject
         fname = os.path.join(self.subdir_root, packagename + '.wrap')
         if not os.path.isfile(fname):