Remove old-style models of built-in functions

Author: owen-mc

go/ql/lib/semmle/go/frameworks/Stdlib.qll

@@ -44,58 +44,6 @@ import semmle.go.frameworks.stdlib.TextTabwriter
 import semmle.go.frameworks.stdlib.TextTemplate
 import semmle.go.frameworks.stdlib.Unsafe
 
-// These are modeled using TaintTracking::FunctionModel because they doesn't have real type signatures,
-// and therefore currently have an InvalidType, not a SignatureType, which breaks Models as Data.
-/**
- * A model of the built-in `append` function, which propagates taint from its arguments to its
- * result.
- */
-private class AppendFunction extends TaintTracking::FunctionModel {
-  AppendFunction() { this = Builtin::append() }
-
-  override predicate hasTaintFlow(FunctionInput inp, FunctionOutput outp) {
-    inp.isParameter(_) and outp.isResult()
-  }
-}
-
-/**
- * A model of the built-in `copy` function, which propagates taint from its second argument
- * to its first.
- */
-private class CopyFunction extends TaintTracking::FunctionModel {
-  CopyFunction() { this = Builtin::copy() }
-
-  override predicate hasTaintFlow(FunctionInput inp, FunctionOutput outp) {
-    inp.isParameter(1) and outp.isParameter(0)
-  }
-}
-
-/**
- * A model of the built-in `min` function, which computes the smallest value of a fixed number of
- * arguments of ordered types. There is at least one argument and "ordered types" includes e.g.
- * strings, so we care about data flow through `min`.
- */
-private class MinFunction extends DataFlow::FunctionModel {
-  MinFunction() { this = Builtin::min_() }
-
-  override predicate hasDataFlow(FunctionInput inp, FunctionOutput outp) {
-    inp.isParameter(_) and outp.isResult()
-  }
-}
-
-/**
- * A model of the built-in `max` function, which computes the largest value of a fixed number of
- * arguments of ordered types. There is at least one argument and "ordered types" includes e.g.
- * strings, so we care about data flow through `max`.
- */
-private class MaxFunction extends DataFlow::FunctionModel {
-  MaxFunction() { this = Builtin::max_() }
-
-  override predicate hasDataFlow(FunctionInput inp, FunctionOutput outp) {
-    inp.isParameter(_) and outp.isResult()
-  }
-}
-
 /** Provides a class for modeling functions which convert strings into integers. */
 module IntegerParser {
   /**