Assert if SubstitutionMap::subst tries to replace a non-pack with a pack

rjmccall · rjmccall · commit 91acf1dd2e4e · 2023-03-17T15:35:41.000-04:00
diff --git a/lib/AST/SubstitutionMap.cpp b/lib/AST/SubstitutionMap.cpp
@@ -458,6 +458,8 @@ SubstitutionMap SubstitutionMap::subst(TypeSubstitutionFn subs,
       continue;
     }
     newSubs.push_back(type.subst(subs, conformances, options));
+    assert(type->is<PackType>() == newSubs.back()->is<PackType>() &&
+           "substitution changed the pack-ness of a replacement type");
   }
 
   SmallVector<ProtocolConformanceRef, 4> newConformances;

Original file line number	Diff line number	Diff line change
`@@ -458,6 +458,8 @@ SubstitutionMap SubstitutionMap::subst(TypeSubstitutionFn subs,`
`458`	`458`	`continue;`
`459`	`459`	`}`
`460`	`460`	`newSubs.push_back(type.subst(subs, conformances, options));`
	`461`	`+ assert(type->is<PackType>() == newSubs.back()->is<PackType>() &&`
	`462`	`+ "substitution changed the pack-ness of a replacement type");`
`461`	`463`	`}`
`462`	`464`
`463`	`465`	`SmallVector<ProtocolConformanceRef, 4> newConformances;`