Improve output when parsing an ini configuration fails

changelog/5650.bugfix.rst

@@ -0,0 +1 @@
+Improved output when parsing an ini configuration file fails.

src/_pytest/config/findpaths.py

@@ -32,7 +32,11 @@ def getcfg(args, config=None):
             for inibasename in inibasenames:
                 p = base.join(inibasename)
                 if exists(p):
+                    try:
                         iniconfig = py.iniconfig.IniConfig(p)
+                    except py.iniconfig.ParseError as exc:
+                        raise UsageError(str(exc))
+
                     if (
                         inibasename == "setup.cfg"
                         and "tool:pytest" in iniconfig.sections

testing/test_config.py

@@ -122,6 +122,14 @@ class TestParseIni:
         config = testdir.parseconfigure(sub)
         assert config.getini("minversion") == "2.0"
 
+    def test_ini_parse_error(self, testdir):
+        testdir.tmpdir.join("pytest.ini").write('addopts = -x')
+        result = testdir.runpytest()
+        assert result.ret != 0
+        result.stderr.fnmatch_lines([
+            "ERROR: *pytest.ini:1: no section header defined"
+        ])
+
     @pytest.mark.xfail(reason="probably not needed")
     def test_confcutdir(self, testdir):
         sub = testdir.mkdir("sub")