From e6a57b22a21e31e6368fce63236e8f19d273c756 Mon Sep 17 00:00:00 2001
From: Owen Mansel-Chan <owen-mc@github.com>
Date: Sun, 31 Oct 2021 13:57:59 +0000
Subject: [PATCH] Add isVariadic() on FuncDecl and Function

---
 ql/lib/semmle/go/Decls.qll  | 2 ++
 ql/lib/semmle/go/Scopes.qll | 6 ++++++
 2 files changed, 8 insertions(+)

diff --git a/ql/lib/semmle/go/Decls.qll b/ql/lib/semmle/go/Decls.qll
index 8cfb78ccc9c..515e3f7b9ef 100644
--- a/ql/lib/semmle/go/Decls.qll
+++ b/ql/lib/semmle/go/Decls.qll
@@ -137,6 +137,8 @@ class FuncDef extends @funcdef, StmtParent, ExprParent {
    */
   DataFlow::CallNode getACall() { result.getACallee() = this }
 
+  predicate isVariadic() { getType().isVariadic() }
+
   override string getAPrimaryQlClass() { result = "FuncDef" }
 }
 
diff --git a/ql/lib/semmle/go/Scopes.qll b/ql/lib/semmle/go/Scopes.qll
index 159f0b6bc5d..d10f5d80919 100644
--- a/ql/lib/semmle/go/Scopes.qll
+++ b/ql/lib/semmle/go/Scopes.qll
@@ -377,6 +377,12 @@ class Function extends ValueEntity, @functionobject {
   /** Gets the declaration of this function, if any. */
   FuncDecl getFuncDecl() { none() }
 
+  predicate isVariadic() {
+    this.(BuiltinFunction).getName() = ["append", "make", "print", "println"]
+    or
+    this.(DeclaredFunction).getFuncDecl().isVariadic()
+  }
+
   /** Holds if this function has no observable side effects. */
   predicate mayHaveSideEffects() { none() }