1 files changed, 24 insertions, 12 deletions

diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 4863b45..28925cc 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -5312,6 +5312,16 @@ void Sema::InstantiateExceptionSpec(SourceLocation PointOfInstantiation,
   if (Proto->getExceptionSpecType() != EST_Uninstantiated)
     return;
 
+  RecursiveInstGuard AlreadyInstantiating(
+      *this, Decl, RecursiveInstGuard::Kind::ExceptionSpec);
+  if (AlreadyInstantiating) {
+    // This exception specification indirectly depends on itself. Reject.
+    // FIXME: Corresponding rule in the standard?
+    Diag(PointOfInstantiation, diag::err_exception_spec_cycle) << Decl;
+    UpdateExceptionSpec(Decl, EST_None);
+    return;
+  }
+
   InstantiatingTemplate Inst(*this, PointOfInstantiation, Decl,
                              InstantiatingTemplate::ExceptionSpecification());
   if (Inst.isInvalid()) {
@@ -5320,13 +5330,6 @@ void Sema::InstantiateExceptionSpec(SourceLocation PointOfInstantiation,
     UpdateExceptionSpec(Decl, EST_None);
     return;
   }
-  if (Inst.isAlreadyInstantiating()) {
-    // This exception specification indirectly depends on itself. Reject.
-    // FIXME: Corresponding rule in the standard?
-    Diag(PointOfInstantiation, diag::err_exception_spec_cycle) << Decl;
-    UpdateExceptionSpec(Decl, EST_None);
-    return;
-  }
 
   // Enter the scope of this instantiation. We don't use
   // PushDeclContext because we don't have a scope.
@@ -5386,8 +5389,6 @@ TemplateDeclInstantiator::InitFunctionInstantiation(FunctionDecl *New,
   if (ActiveInst.Kind == ActiveInstType::ExplicitTemplateArgumentSubstitution ||
       ActiveInst.Kind == ActiveInstType::DeducedTemplateArgumentSubstitution) {
     if (isa<FunctionTemplateDecl>(ActiveInst.Entity)) {
-      SemaRef.InstantiatingSpecializations.erase(
-          {ActiveInst.Entity->getCanonicalDecl(), ActiveInst.Kind});
       atTemplateEnd(SemaRef.TemplateInstCallbacks, SemaRef, ActiveInst);
       ActiveInst.Kind = ActiveInstType::TemplateInstantiation;
       ActiveInst.Entity = New;
@@ -5545,6 +5546,12 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
     Function = const_cast<FunctionDecl*>(ExistingDefn);
   }
 
+#ifndef NDEBUG
+  RecursiveInstGuard AlreadyInstantiating(*this, Function,
+                                          RecursiveInstGuard::Kind::Template);
+  assert(!AlreadyInstantiating && "should have been caught by caller");
+#endif
+
   // Find the function body that we'll be substituting.
   const FunctionDecl *PatternDecl = Function->getTemplateInstantiationPattern();
   assert(PatternDecl && "instantiating a non-template");
@@ -5684,7 +5691,7 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
   }
 
   InstantiatingTemplate Inst(*this, PointOfInstantiation, Function);
-  if (Inst.isInvalid() || Inst.isAlreadyInstantiating())
+  if (Inst.isInvalid())
     return;
   PrettyDeclStackTraceEntry CrashInfo(Context, Function, SourceLocation(),
                                       "instantiating function definition");
@@ -6253,6 +6260,11 @@ void Sema::InstantiateVariableDefinition(SourceLocation PointOfInstantiation,
   if (TSK == TSK_ExplicitSpecialization)
     return;
 
+  RecursiveInstGuard AlreadyInstantiating(*this, Var,
+                                          RecursiveInstGuard::Kind::Template);
+  if (AlreadyInstantiating)
+    return;
+
   // Find the pattern and the arguments to substitute into it.
   VarDecl *PatternDecl = Var->getTemplateInstantiationPattern();
   assert(PatternDecl && "no pattern for templated variable");
@@ -6276,7 +6288,7 @@ void Sema::InstantiateVariableDefinition(SourceLocation PointOfInstantiation,
       // FIXME: Factor out the duplicated instantiation context setup/tear down
       // code here.
       InstantiatingTemplate Inst(*this, PointOfInstantiation, Var);
-      if (Inst.isInvalid() || Inst.isAlreadyInstantiating())
+      if (Inst.isInvalid())
         return;
       PrettyDeclStackTraceEntry CrashInfo(Context, Var, SourceLocation(),
                                           "instantiating variable initializer");
@@ -6380,7 +6392,7 @@ void Sema::InstantiateVariableDefinition(SourceLocation PointOfInstantiation,
   }
 
   InstantiatingTemplate Inst(*this, PointOfInstantiation, Var);
-  if (Inst.isInvalid() || Inst.isAlreadyInstantiating())
+  if (Inst.isInvalid())
     return;
   PrettyDeclStackTraceEntry CrashInfo(Context, Var, SourceLocation(),
                                       "instantiating variable definition");