Hotfix: Crash due to ContainerDecl->members being altered whislt iterated over (#1580)

* #include an absolute path didn't work - because paths were taken to always be relative.

* Access the members iteration in _ensureAllDeclsRec via indices to avoid a change in the array invalidating the list.

* Fix another iterator of members in SemanticVisitor

* Slight improvements to comments - main purpose is to kick a new build.

1 files changed, 25 insertions, 8 deletions

diff --git a/source/slang/slang-check-decl.cpp b/source/slang/slang-check-decl.cpp
index a51dc0313..0735f4620 100644
--- a/source/slang/slang-check-decl.cpp
+++ b/source/slang/slang-check-decl.cpp
@@ -783,14 +783,23 @@ namespace Slang
 
         // If `decl` is a container, then we want to ensure its children.
         if(auto containerDecl = as<ContainerDecl>(decl))
-        {
-            // As an exception, if any of the child is a `ScopeDecl`,
-            // then that indicates that it represents a scope for local
-            // declarations under a statement (e.g., in a function body),
-            // and we don't want to check such local declarations here.
-            //
-            for(auto childDecl : containerDecl->members)
+        {            
+            // NOTE! We purposefully do not iterate with the for(auto childDecl : containerDecl->members) here,
+            // because the visitor may add to `members` whilst iteration takes place, invalidating the iterator
+            // and likely a crash.
+            // 
+            // Accessing the members via index side steps the issue.
+            const auto& members = containerDecl->members;
+            for(Index i = 0; i < members.getCount(); ++i)
             {
+                Decl* childDecl = members[i];
+
+                // As an exception, if any of the child is a `ScopeDecl`,
+                // then that indicates that it represents a scope for local
+                // declarations under a statement (e.g., in a function body),
+                // and we don't want to check such local declarations here.
+                //
+
                 if(as<ScopeDecl>(childDecl))
                     continue;
 
@@ -1126,8 +1135,16 @@ namespace Slang
     {
         genericDecl->setCheckState(DeclCheckState::ReadyForLookup);
 
-        for (auto m : genericDecl->members)
+        // NOTE! We purposefully do not iterate with the for(auto m : genericDecl->members) here,
+        // because the visitor may add to `members` whilst iteration takes place, invalidating the iterator
+        // and likely a crash.
+        // 
+        // Accessing the members via index side steps the issue.
+        const auto& members = genericDecl->members;
+        for (Index i = 0; i < members.getCount(); ++i)
         {
+            Decl* m = members[i];
+
             if (auto typeParam = as<GenericTypeParamDecl>(m))
             {
                 ensureDecl(typeParam, DeclCheckState::ReadyForReference);