diff --git a/sphinx/ext/intersphinx.py b/sphinx/ext/intersphinx.py
index c3cf0eec7..ce10f1228 100644
--- a/sphinx/ext/intersphinx.py
+++ b/sphinx/ext/intersphinx.py
@@ -495,20 +495,11 @@ class IntersphinxRole(SphinxRole):
                            location=(self.env.docname, self.lineno))
             return [], []
 
-        # extract inventory specification
-        inventory = None
-        if self.text.startswith('\\:'):
-            # escaped :, so not a real inventory specification
-            self.text = self.text[1:]
-        elif self.text[0] == ':':  # format: :inv:normalRoleArg
-            inventory = self.text.split(':')[1]
-            self.text = self.text[(len(inventory) + 2):]
-
         result, messages = self.invoke_role(role_name)
         for node in result:
             if isinstance(node, pending_xref):
                 node['intersphinx'] = True
-                node['inventory'] = inventory
+                node['inventory'] = None
 
         return result, messages
 
@@ -574,8 +565,11 @@ class IntersphinxRoleResolver(ReferencesResolver):
             else:
                 newnode = resolve_reference_any_inventory(self.env, False, node, contnode)
             if newnode is None:
-                # no warning, the normal missing_reference handler will do that
-                pass
+                typ = node['reftype']
+                msg = (__('external %s:%s reference target not found: %s') %
+                       (node['refdomain'], typ, node['reftarget']))
+                logger.warning(msg, location=node, type='ref', subtype=typ)
+                node.replace_self(contnode)
             else:
                 node.replace_self(newnode)
 
diff --git a/tests/roots/test-ext-intersphinx-role/index.rst b/tests/roots/test-ext-intersphinx-role/index.rst
index 164f2cfd4..bb7a6c4f1 100644
--- a/tests/roots/test-ext-intersphinx-role/index.rst
+++ b/tests/roots/test-ext-intersphinx-role/index.rst
@@ -1,26 +1,21 @@
-:external:py:mod:`module1`
-:external:py:mod:`inv:module2`
+- ``module1`` is only defined in ``inv``:
+  :external:py:mod:`module1`
 
-.. py:module:: module1
+.. py:module:: module2
 
-:external:py:func:`func`
-:external:py:func:`inv:func`
-:external:py:meth:`Foo.bar`
-:external:py:meth:`inv:Foo.bar`
+- ``module2`` is defined here and also in ``inv``, but should resolve to inv:
+  :external:py:mod:`module2`
 
-:external:c:func:`CFunc`
-:external:c:func:`inv:CFunc`
-:external:doc:`docname`
-:external:doc:`inv:docname`
-:external:option:`ls -l`
-:external:option:`inv:ls -l`
+- ``module3`` is not defined anywhere, so should warn:
+  :external:py:mod:`module3`
 
-.. cpp:type:: std::uint8_t
-.. cpp:class:: foo::Bar
+.. py:module:: module10
 
-:external:cpp:type:`std::uint8_t`
-:external:cpp:class:`inv:foo::Bar`
-:external:cpp:func:`:inv2:foo::Bar::baz`
+- ``module10`` is only defined here, but should still not be resolved to:
+  :external:py:mod:`module10`
 
-:external:cpp:type:`FoonsTitle <foons>`
-:external:cpp:type:`inv:BarType <foons::bartype>`
\ No newline at end of file
+
+- a function in inv:
+  :external:py:func:`module1.func`
+- a method, but with old style inventory prefix, which shouldn't work:
+  :external:py:meth:`inv:Foo.bar`
diff --git a/tests/test_ext_intersphinx.py b/tests/test_ext_intersphinx.py
index a1118e48d..ec2aad440 100644
--- a/tests/test_ext_intersphinx.py
+++ b/tests/test_ext_intersphinx.py
@@ -527,7 +527,7 @@ def test_inspect_main_url(capsys):
 
 
 @pytest.mark.sphinx('html', testroot='ext-intersphinx-role')
-def test_intersphinx_role(app):
+def test_intersphinx_role(app, warning):
     inv_file = app.srcdir / 'inventory'
     inv_file.write_bytes(inventory_v2)
     app.config.intersphinx_mapping = {
@@ -542,21 +542,13 @@ def test_intersphinx_role(app):
 
     app.build()
     content = (app.outdir / 'index.html').read_text()
+    wStr = warning.getvalue()
 
-    targets = (
-        'foo.html#module-module1',
-        'foo.html#module-module2',
-        'sub/foo.html#module1.func',
-        'index.html#foo.Bar.baz',
-        'cfunc.html#CFunc',
-        'docname.html',
-        'index.html#cmdoption-ls-l',
-        'index.html#std_uint8_t',
-        'index.html#foons',
-        'index.html#foons_bartype',
-    )
     html = '<a class="reference external" href="http://example.org/{}" title="(in foo v2.0)">'
-    for t in targets:
-        assert html.format(t) in content
+    assert html.format('foo.html#module-module1') in content
+    assert html.format('foo.html#module-module2') in content
+    assert "WARNING: external py:mod reference target not found: module3" in wStr
+    assert "WARNING: external py:mod reference target not found: module10" in wStr
 
-    assert html.format('index.html#cpp_foo_bar_baz') not in content
+    assert html.format('sub/foo.html#module1.func') in content
+    assert "WARNING: external py:meth reference target not found: inv:Foo.bar" in wStr