From: Chandler Carruth <chandlerc@gmail.com>
Date: Tue, 7 Feb 2017 03:34:08 +0000 (+0000)
Subject: [PM] Defend against getting slightly wrong template arguments passed
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=869cf60647b9450452132695f0a5fc8d16f627a2;p=llvm

[PM] Defend against getting slightly wrong template arguments passed
into CRTP base classes.

This can sometimes happen and not cause an immediate failure when the
derived class is, itself, a template. You can end up essentially calling
methods on the wrong derived type but a type where many things will
appear to "work".

To fail fast and with a clear error message we can use a static_assert,
but we have to stash that static_assert inside a method body or nested
type that won't need to be completed while building the base class. I've
tried to pick a reasonably small number of places that seemed like they
would definitely get triggered on use.

This is the last of the patch series defending against this that I have
planned, so far no bugs other than the original were found.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294275 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/unittests/Transforms/Scalar/LoopPassManagerTest.cpp b/unittests/Transforms/Scalar/LoopPassManagerTest.cpp
index 0209927b9f4..227060f0a46 100644
--- a/unittests/Transforms/Scalar/LoopPassManagerTest.cpp
+++ b/unittests/Transforms/Scalar/LoopPassManagerTest.cpp
@@ -46,7 +46,10 @@ public:
 
     DerivedT *Handle;
 
-    Analysis(DerivedT &Handle) : Handle(&Handle) {}
+    Analysis(DerivedT &Handle) : Handle(&Handle) {
+      static_assert(std::is_base_of<MockAnalysisHandleBase, DerivedT>::value,
+                    "Must pass the derived type to this template!");
+    }
 
   public:
     class Result {
@@ -152,7 +155,10 @@ public:
 
     DerivedT *Handle;
 
-    Pass(DerivedT &Handle) : Handle(&Handle) {}
+    Pass(DerivedT &Handle) : Handle(&Handle) {
+      static_assert(std::is_base_of<MockPassHandleBase, DerivedT>::value,
+                    "Must pass the derived type to this template!");
+    }
 
   public:
     PreservedAnalyses run(IRUnitT &IR, AnalysisManagerT &AM,