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)

4 files changed, 12 insertions, 7 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
 
diff --git a/run_unittests.py b/run_unittests.py
index 09d1c5e..214bc16 100755
--- a/run_unittests.py
+++ b/run_unittests.py
@@ -2660,13 +2660,14 @@ recommended as it is not supported on some platforms''')
         out = self.init(testdir)
         # Parent project warns correctly
         self.assertRegex(out, "WARNING: Project targetting '>=0.45'.*'0.47.0': dict")
-        # Subproject warns correctly
-        self.assertRegex(out, "|WARNING: Project targetting '>=0.40'.*'0.44.0': disabler")
+        # Subprojects warn correctly
+        self.assertRegex(out, r"\|WARNING: Project targetting '>=0.40'.*'0.44.0': disabler")
+        self.assertRegex(out, r"\|WARNING: Project targetting '!=0.40'.*'0.44.0': disabler")
         # Subproject has a new-enough meson_version, no warning
         self.assertNotRegex(out, "WARNING: Project targetting.*Python")
         # Ensure a summary is printed in the subproject and the outer project
-        self.assertRegex(out, "|WARNING: Project specifies a minimum meson_version '>=0.40'")
-        self.assertRegex(out, "| * 0.44.0: {'disabler'}")
+        self.assertRegex(out, r"\|WARNING: Project specifies a minimum meson_version '>=0.40'")
+        self.assertRegex(out, r"\| \* 0.44.0: {'disabler'}")
         self.assertRegex(out, "WARNING: Project specifies a minimum meson_version '>=0.45'")
         self.assertRegex(out, " * 0.47.0: {'dict'}")
 
diff --git a/test cases/unit/41 featurenew subprojects/meson.build b/test cases/unit/41 featurenew subprojects/meson.build
index 27898cd..d136bed 100644
--- a/test cases/unit/41 featurenew subprojects/meson.build
+++ b/test cases/unit/41 featurenew subprojects/meson.build
@@ -4,3 +4,4 @@ foo = {}
 
 subproject('foo')
 subproject('bar')
+subproject('baz')
diff --git a/test cases/unit/41 featurenew subprojects/subprojects/baz/meson.build b/test cases/unit/41 featurenew subprojects/subprojects/baz/meson.build
new file mode 100644
index 0000000..811e7aa
--- /dev/null
+++ b/test cases/unit/41 featurenew subprojects/subprojects/baz/meson.build
@@ -0,0 +1,3 @@
+project('baz subproject', meson_version: '!=0.40')
+
+disabler()