warn against self-binding circularity

docs/genqlient.yaml

@@ -143,6 +143,9 @@ optional_generic_type: github.com/organisation/repository/example.Type
 # guarantees that the fields requested in the query match those present in
 # the Go type.
 #
+# Note: if binding to types in the same package as the generated code, make
+# sure you don't bind to generated types! Otherwise, things get very circular.
+#
 # To get equivalent behavior in just one query, use @genqlient(bind: ...);
 # see genqlient_directive.graphql for more details.
 bindings:
@@ -228,6 +231,9 @@ bindings:
 # to the bindings map, above, for each exported type in the package.  Multiple
 # packages may be specified, and later ones take precedence over earlier ones.
 # Explicit entries in bindings take precedence over all package bindings.
+#
+# Note: make sure this isn't the package with your generated code, or things
+# will get circular very fast.
 package_bindings:
 - package: github.com/you/yourpkg/models
 

generate/config.go

@@ -256,6 +256,11 @@ func (c *Config) ValidateAndFillDefaults(baseDir string) error {
 					binding.Package)
 			}
 
+			if binding.Package == c.pkgPath {
+				warn(errorf(nil, "warning: binding to the same package as your generated "+
+					"code ('%v'); this will probably cause circularity issues", c.pkgPath))
+			}
+
 			mode := packages.NeedDeps | packages.NeedTypes
 			pkgs, err := packages.Load(&packages.Config{
 				Mode: mode,