ENH,BUG:distutils Remove the origins from the implied features

  This issue happens only when two features imply each other,
  it doesn't cause any serious problem, it only effects on reports,
  and when it comes to generating features tables for the upcoming doc.

1 files changed, 39 insertions, 14 deletions

diff --git a/numpy/distutils/ccompiler_opt.py b/numpy/distutils/ccompiler_opt.py
index 0488173ca..9fc558416 100644
--- a/numpy/distutils/ccompiler_opt.py
+++ b/numpy/distutils/ccompiler_opt.py
@@ -1222,9 +1222,31 @@ class _Feature:
             return rank
         return sorted(names, reverse=reverse, key=sort_cb)
 
-    def feature_implies(self, names):
-        """Return a set of CPU features that implied by 'names'"""
-        def get_implies(name, _caller=[]):
+    def feature_implies(self, names, keep_origins=False):
+        """
+        Return a set of CPU features that implied by 'names'
+
+        Parameters
+        ----------
+        'names': str(single feature) or sequence
+            CPU feature names in uppercase.
+
+        'keep_origins': bool
+            if False(default) then the returned set will not contain any
+            features from 'names'. This case happens only when two features
+            imply each other.
+
+        Examples
+        --------
+        >>> self.feature_implies("SSE3")
+        {'SSE', 'SSE2'}
+        >>> self.feature_implies("SSE2")
+        {'SSE'}
+        >>> self.feature_implies("SSE2", keep_origins=True)
+        # 'SSE2' found here since 'SSE' and 'SSE2' imply each other
+        {'SSE', 'SSE2'}
+        """
+        def get_implies(name, _caller=set()):
             implies = set()
             d = self.feature_supported[name]
             for i in d.get("implies", []):
@@ -1233,17 +1255,20 @@ class _Feature:
                     # infinity recursive guard since
                     # features can imply each other
                     continue
-                _caller.append(name)
+                _caller.add(name)
                 implies = implies.union(get_implies(i, _caller))
             return implies
 
         if isinstance(names, str):
-            return get_implies(names)
-
-        assert(hasattr(names, "__iter__"))
-        implies = set()
-        for n in names:
-            implies = implies.union(get_implies(n))
+            implies = get_implies(names)
+            names = [names]
+        else:
+            assert(hasattr(names, "__iter__"))
+            implies = set()
+            for n in names:
+                implies = implies.union(get_implies(n))
+        if not keep_origins:
+            implies.difference_update(names)
         return implies
 
     def feature_implies_c(self, names):
@@ -1270,21 +1295,21 @@ class _Feature:
 
         Examples
         --------
-        >>> self.feature_untied(["SSE2", "SSE3", "SSE41"])
+        >>> self.feature_ahead(["SSE2", "SSE3", "SSE41"])
         ["SSE41"]
         # assume AVX2 and FMA3 implies each other and AVX2
         # is the highest interest
-        >>> self.feature_untied(["SSE2", "SSE3", "SSE41", "AVX2", "FMA3"])
+        >>> self.feature_ahead(["SSE2", "SSE3", "SSE41", "AVX2", "FMA3"])
         ["AVX2"]
         # assume AVX2 and FMA3 don't implies each other
-        >>> self.feature_untied(["SSE2", "SSE3", "SSE41", "AVX2", "FMA3"])
+        >>> self.feature_ahead(["SSE2", "SSE3", "SSE41", "AVX2", "FMA3"])
         ["AVX2", "FMA3"]
         """
         assert(
             not isinstance(names, str)
             and hasattr(names, '__iter__')
         )
-        implies = self.feature_implies(names)
+        implies = self.feature_implies(names, keep_origins=True)
         ahead = [n for n in names if n not in implies]
         if len(ahead) == 0:
             # return the highest interested feature