Fix lookup to prevent finding `typedef` itself. (#3848)

7 files changed, 45 insertions, 13 deletions

diff --git a/source/slang/slang-ast-support-types.h b/source/slang/slang-ast-support-types.h
index e4e3be384..196a1d002 100644
--- a/source/slang/slang-ast-support-types.h
+++ b/source/slang/slang-ast-support-types.h
@@ -1421,6 +1421,9 @@ namespace Slang
         Scope*              scope       = nullptr;
         Scope*              endScope    = nullptr;
 
+        // A decl to exclude from the lookup, used to exclude the current decl being checked, such as in typedef Foo Foo;
+        // to avoid finding itself.
+        Decl* declToExclude = nullptr;
         LookupMask          mask        = LookupMask::Default;
         LookupOptions       options     = LookupOptions::None;
 
diff --git a/source/slang/slang-check-decl.cpp b/source/slang/slang-check-decl.cpp
index c844fb82a..ed97e412d 100644
--- a/source/slang/slang-check-decl.cpp
+++ b/source/slang/slang-check-decl.cpp
@@ -6203,7 +6203,8 @@ namespace Slang
 
     void SemanticsDeclHeaderVisitor::visitTypeDefDecl(TypeDefDecl* decl)
     {
-        decl->type = CheckProperType(decl->type);
+        SemanticsVisitor visitor(withDeclToExcludeFromLookup(decl));
+        decl->type = visitor.CheckProperType(decl->type);
         checkVisibility(decl);
     }
 
diff --git a/source/slang/slang-check-expr.cpp b/source/slang/slang-check-expr.cpp
index a31e17123..ad6bb2a86 100644
--- a/source/slang/slang-check-expr.cpp
+++ b/source/slang/slang-check-expr.cpp
@@ -2601,8 +2601,7 @@ namespace Slang
         }
         expr->type = QualType(m_astBuilder->getErrorType());
         auto lookupResult = lookUp(
-            m_astBuilder,
-            this, expr->name, expr->scope);
+            m_astBuilder, this, expr->name, expr->scope, LookupMask::Default, false, getDeclToExcludeFromLookup());
         
         bool diagnosed = false;
         lookupResult = filterLookupResultByVisibilityAndDiagnose(lookupResult, expr->loc, diagnosed);
@@ -3703,7 +3702,9 @@ namespace Slang
                                 this,
                                 expr->name,
                                 namespaceDecl,
-                                DeclRef(namespaceDecl));
+                                DeclRef(namespaceDecl),
+                                LookupMask::Default,
+                                getDeclToExcludeFromLookup());
                             AddToLookupResult(globalLookupResult, nsLookupResult);
                         }
                     }
diff --git a/source/slang/slang-check-impl.h b/source/slang/slang-check-impl.h
index 278fc3265..a3ecc28b4 100644
--- a/source/slang/slang-check-impl.h
+++ b/source/slang/slang-check-impl.h
@@ -921,6 +921,15 @@ namespace Slang
             return result;
         }
 
+        SemanticsContext withDeclToExcludeFromLookup(Decl* decl)
+        {
+            SemanticsContext result(*this);
+            result.m_declToExcludeFromLookup = decl;
+            return result;
+        }
+
+        Decl* getDeclToExcludeFromLookup() { return m_declToExcludeFromLookup; }
+
     private:
         SharedSemanticsContext* m_shared = nullptr;
 
@@ -928,6 +937,7 @@ namespace Slang
 
         ExprLocalScope* m_exprLocalScope = nullptr;
 
+        Decl* m_declToExcludeFromLookup = nullptr;
 
     protected:
         // TODO: consider making more of this state `private`...
diff --git a/source/slang/slang-lookup.cpp b/source/slang/slang-lookup.cpp
index 301c86aa8..6a62303d2 100644
--- a/source/slang/slang-lookup.cpp
+++ b/source/slang/slang-lookup.cpp
@@ -213,6 +213,8 @@ static void _lookUpDirectAndTransparentMembers(
             // it's unchecked or being checked then it isn't declared yet.
             if(!request.shouldConsiderAllLocalNames() && request.semantics && _isUncheckedLocalVar(m))
                 continue;
+            if (m == request.declToExclude)
+                continue;
 
             if (!DeclPassesLookupMask(m, request.mask))
                 continue;
@@ -253,13 +255,15 @@ LookupRequest initLookupRequest(
     Name* name,
     LookupMask mask,
     LookupOptions options,
-    Scope* scope)
+    Scope* scope,
+    Decl* declToExclude)
 {
     LookupRequest request;
     request.semantics = semantics;
     request.mask = mask;
     request.options = options;
     request.scope = scope;
+    request.declToExclude = declToExclude;
 
     if (semantics && semantics->getSession() &&
         name == semantics->getSession()->getCompletionRequestTokenName())
@@ -275,9 +279,10 @@ LookupResult lookUpDirectAndTransparentMembers(
     Name*                   name,
     ContainerDecl*          containerDecl,
     DeclRef<Decl>           parentDeclRef,
-    LookupMask              mask)
+    LookupMask              mask,
+    Decl*                   declToExclude)
 {
-    LookupRequest request = initLookupRequest(semantics, name, mask, LookupOptions::None, nullptr);
+    LookupRequest request = initLookupRequest(semantics, name, mask, LookupOptions::None, nullptr, declToExclude);
     LookupResult result;
     _lookUpDirectAndTransparentMembers(
         astBuilder,
@@ -892,13 +897,14 @@ LookupResult lookUp(
     Name*               name,
     Scope*              scope,
     LookupMask          mask,
-    bool                considerAllLocalNamesInScope)
+    bool                considerAllLocalNamesInScope,
+    Decl*               declToExclude)
 {
     LookupResult result;
     const auto options = considerAllLocalNamesInScope
         ? LookupOptions::ConsiderAllLocalNamesInScope
         : LookupOptions::None;
-    LookupRequest request = initLookupRequest(semantics, name, mask, options, scope);
+    LookupRequest request = initLookupRequest(semantics, name, mask, options, scope, declToExclude);
     _lookUpInScopes(astBuilder, name, request, result);
     return result;
 }
@@ -913,7 +919,7 @@ LookupResult lookUpMember(
     LookupOptions       options)
 {
     LookupResult result;
-    LookupRequest request = initLookupRequest(semantics, name, mask, options, sourceScope);
+    LookupRequest request = initLookupRequest(semantics, name, mask, options, sourceScope, nullptr);
     _lookUpMembersInType(astBuilder, name, type, request, result, nullptr);
     return result;
 }
diff --git a/source/slang/slang-lookup.h b/source/slang/slang-lookup.h
index 84b453bf2..fb7511428 100644
--- a/source/slang/slang-lookup.h
+++ b/source/slang/slang-lookup.h
@@ -19,7 +19,8 @@ LookupResult lookUp(
     Name*               name,
     Scope*              scope,
     LookupMask          mask = LookupMask::Default,
-    bool                considerAllLocalNamesInScope = false);
+    bool                considerAllLocalNamesInScope = false,
+    Decl*               declToExclude = nullptr);
 
 // Perform member lookup in the context of a type
 LookupResult lookUpMember(
@@ -38,7 +39,8 @@ LookupResult lookUpDirectAndTransparentMembers(
     Name*                   name,
     ContainerDecl*          containerDecl,
     DeclRef<Decl>           parentDeclRef,       // The parent of the resulting declref.
-    LookupMask              mask = LookupMask::Default);
+    LookupMask              mask = LookupMask::Default,
+    Decl*                   declToExclude = nullptr);
 
 // TODO: this belongs somewhere else
 
diff --git a/source/slang/slang-parser.cpp b/source/slang/slang-parser.cpp
index b99df18e4..cc3a661f3 100644
--- a/source/slang/slang-parser.cpp
+++ b/source/slang/slang-parser.cpp
@@ -2576,11 +2576,20 @@ namespace Slang
             typeSpec.expr = parseFuncTypeExpr(parser);
             return typeSpec;
         }
+        
+        bool inGlobalScope = false;
+        if (AdvanceIf(parser, TokenType::Scope))
+        {
+            inGlobalScope = true;
+        }
 
         Token typeName = parser->ReadToken(TokenType::Identifier);
 
         auto basicType = parser->astBuilder->create<VarExpr>();
-        basicType->scope = parser->currentLookupScope;
+        if (inGlobalScope)
+            basicType->scope = parser->currentModule->ownedScope;
+        else
+            basicType->scope = parser->currentLookupScope;
         basicType->loc = typeName.loc;
         basicType->name = typeName.getNameOrNull();