Correct version_compare_condition_with_min()

Correct version_compare_condition_with_min() for the case where no minimum
version is established by the version constraint.  Add a simple test.

Also fix test_feature_check_usage_subprojects by escaping regex
metacharacters.

if |condition| is '<', '<=' or '!=', the minimum version satisfying the
condition is 0, so the minimum version for a feature is never met.

if |condition| is '>=' or '==', the minimum version satisfying the condition
is the version compared with, so the minimum version for a feature must be
less than or equal to that.

if |condition| is '>', the minimum version satisfying the condition is
greater than the version compared with, so the minimum version for a feature
must be less than that

(it's this last condition that makes this function necessary, as in all
other cases we could establish a definite minimum version which we could
compare to see if it's less than or equal to the current version)

1 files changed, 3 insertions, 3 deletions

diff --git a/mesonbuild/mesonlib.py b/mesonbuild/mesonlib.py
index 05a77cd..8a2dc0c 100644
--- a/mesonbuild/mesonlib.py
+++ b/mesonbuild/mesonlib.py
@@ -493,9 +493,9 @@ def version_compare_condition_with_min(condition, minimum):
         cmpop = operator.le
         condition = condition[2:]
     elif condition.startswith('<='):
-        return True
+        return False
     elif condition.startswith('!='):
-        return True
+        return False
     elif condition.startswith('=='):
         cmpop = operator.le
         condition = condition[2:]
@@ -506,7 +506,7 @@ def version_compare_condition_with_min(condition, minimum):
         cmpop = operator.lt
         condition = condition[1:]
     elif condition.startswith('<'):
-        return True
+        return False
     else:
         cmpop = operator.le