bug 1257542 - check_prog template should sanity check that progs is not a string. r=glandium

In Python parens around an expression without a trailing comma is not a tuple,
so ('foo') == 'foo'. This is really easy to screw up with check_progs, which
coerces progs to a list and would give you ['f','o','o'] in this case. This
patch enforces that the progs argument is a tuple or list and errors if it
is not.

MozReview-Commit-ID: 7BJZuF9B8D5

--HG--
extra : rebase_source : 5db9a6b4bb9ef7195c2513407810093bff5e9174
extra : amend_source : f67ab46c2ac00a2a95cfc67e9763ac12b690ac14

build/moz.configure/checks.configure

@@ -52,6 +52,8 @@ def check_prog(var, progs, allow_missing=False):
     option(env=var, nargs=1, help='Path to the %s program' % var.lower())
 
     not_found = 'not found'
+    if not (isinstance(progs, tuple) or isinstance(progs, list)):
+        configure_error('progs should be a list or tuple!')
     progs = list(progs)
 
     @depends(var)

build/moz.configure/util.configure

@@ -7,6 +7,7 @@
 @template
 @advanced
 def warn(*args):
+    'Print a warning.'
     import sys
     print(*args, file=sys.stderr)
     sys.stderr.flush()
@@ -15,12 +16,23 @@ def warn(*args):
 @template
 @advanced
 def error(*args):
+    'Print an error and terminate configure.'
     import sys
     print(*args, file=sys.stderr)
     sys.stderr.flush()
     sys.exit(1)
 
 
+@template
+@advanced
+def configure_error(message):
+    '''Raise a programming error and terminate configure.
+    Primarily for use in moz.configure templates to sanity check
+    their inputs from moz.configure usage.'''
+    from mozbuild.configure import ConfigureError
+    raise ConfigureError(message)
+
+
 @template
 @advanced
 def is_absolute_or_relative(path):

python/mozbuild/mozbuild/configure/__init__.py

@@ -93,7 +93,7 @@ class ConfigureSandbox(dict):
     BUILTINS = ReadOnlyDict({
         b: __builtins__[b]
         for b in ('None', 'False', 'True', 'int', 'bool', 'any', 'all', 'len',
-                  'list', 'set', 'dict')
+                  'list', 'tuple', 'set', 'dict', 'isinstance')
     }, __import__=forbidden_import)
 
     # Expose a limited set of functions from os.path