From 5175f1dcbe3485570b06a4dccf3575cc69c075cf Mon Sep 17 00:00:00 2001
From: Max Schaefer <max@semmle.com>
Date: Fri, 13 Mar 2020 12:57:26 +0000
Subject: [PATCH] Take promoted methods into account when computing method
 sets.

---
 ql/src/semmle/go/Types.qll | 39 +++++++++++++++++++++++++++++++++++---
 1 file changed, 36 insertions(+), 3 deletions(-)

diff --git a/ql/src/semmle/go/Types.qll b/ql/src/semmle/go/Types.qll
index c341656621b..d2b734e0785 100644
--- a/ql/src/semmle/go/Types.qll
+++ b/ql/src/semmle/go/Types.qll
@@ -441,11 +441,29 @@ class PointerType extends @pointertype, CompositeType {
   override Package getPackage() { result = this.getBaseType().getPackage() }
 
   override Method getMethod(string m) {
-    // https://golang.org/ref/spec#Method_sets: "the method set of a pointer type *T is
-    // the set of all methods declared with receiver *T or T"
     result = CompositeType.super.getMethod(m)
     or
+    // https://golang.org/ref/spec#Method_sets: "the method set of a pointer type *T is
+    // the set of all methods declared with receiver *T or T"
     result = getBaseType().getMethod(m)
+    or
+    // promoted methods from embedded types
+    exists(StructType s, Type embedded |
+      s = getBaseType().(NamedType).getUnderlyingType() and
+      s.hasOwnField(_, _, embedded, true) and
+      // ensure that `m` can be promoted
+      not s.hasOwnField(_, m, _, _) and
+      not exists(Method m2 | m2.getReceiverBaseType() = getBaseType() and m2.getName() = m)
+    |
+      result = embedded.getMethod(m)
+      or
+      // If S contains an embedded field T, the method set of *S includes promoted methods with receiver T or T*
+      not embedded instanceof PointerType and
+      result = embedded.getPointerType().getMethod(m)
+      or
+      // If S contains an embedded field *T, the method set of *S includes promoted methods with receiver T or *T
+      result = embedded.(PointerType).getBaseType().getMethod(m)
+    )
   }
 
   override string pp() { result = "* " + getBaseType().pp() }
@@ -566,7 +584,7 @@ class SendRecvChanType extends @sendrcvchantype, ChanType {
 
 /** A named type. */
 class NamedType extends @namedtype, CompositeType {
-  /** Gets a method with name `m` defined on this type. */
+  /** Gets a method with name `m` defined on this type or its pointer type. */
   MethodDecl getMethodDecl(string m) {
     result.getName() = m and
     this = result.getReceiverBaseType()
@@ -580,6 +598,21 @@ class NamedType extends @namedtype, CompositeType {
     or
     methodhosts(result, this) and
     result.getName() = m
+    or
+    // handle promoted methods
+    exists(StructType s, Type embedded |
+      s = getBaseType() and
+      s.hasOwnField(_, _, embedded, true) and
+      // ensure `m` can be promoted
+      not s.hasOwnField(_, m, _, _) and
+      not exists(Method m2 | m2.getReceiverType() = this and m2.getName() = m)
+    |
+      // If S contains an embedded field T, the method set of S includes promoted methods with receiver T
+      result = embedded.getMethod(m)
+      or
+      // If S contains an embedded field *T, the method set of S includes promoted methods with receiver T or *T
+      result = embedded.(PointerType).getBaseType().getMethod(m)
+    )
   }
 
   override Type getUnderlyingType() { result = getBaseType().getUnderlyingType() }