Issue 9050 - Too early instantiation of template structs

src/clone.c

@@ -76,6 +76,7 @@ FuncDeclaration *AggregateDeclaration::hasIdentityOpAssign(Scope *sc)
         unsigned oldspec = global.speculativeGag;   // template opAssign fbody makes it.
         global.speculativeGag = global.gag;
         sc = sc->push();
+        sc->tinst = NULL;
         sc->speculative = true;
 
         for (size_t i = 0; i < 2; i++)
@@ -419,6 +420,7 @@ FuncDeclaration *AggregateDeclaration::hasIdentityOpEquals(Scope *sc)
             unsigned oldspec = global.speculativeGag;   // template opAssign fbody makes it.
             global.speculativeGag = global.gag;
             sc = sc->push();
+            sc->tinst = NULL;
             sc->speculative = true;
 
             for (size_t j = 0; j < 2; j++)

src/template.c

@@ -5198,6 +5198,7 @@ TemplateInstance::TemplateInstance(Loc loc, Identifier *ident)
     this->instantiatingModule = NULL;
     this->inst = NULL;
     this->tinst = NULL;
+    this->deferred = NULL;
     this->argsym = NULL;
     this->aliasdecl = NULL;
     this->semantictiargsdone = false;
@@ -5228,6 +5229,7 @@ TemplateInstance::TemplateInstance(Loc loc, TemplateDeclaration *td, Objects *ti
     this->instantiatingModule = NULL;
     this->inst = NULL;
     this->tinst = NULL;
+    this->deferred = NULL;
     this->argsym = NULL;
     this->aliasdecl = NULL;
     this->semantictiargsdone = true;
@@ -5773,9 +5775,63 @@ void TemplateInstance::semantic(Scope *sc, Expressions *fargs)
         semantic2(sc2);
     }
 
-    if (sc->func)
+    if (sc->func && aliasdecl && aliasdecl->toAlias()->isFuncDeclaration())
     {
+        /* Template function instantiation should run semantic3 immediately
+         * for attribute inference.
+         */
+        //printf("function semantic3 %s inside %s\n", toChars(), sc->func->toChars());
+        trySemantic3(sc2);
+    }
+    else if (sc->func && !tinst)
+    {
+        /* If a template is instantiated inside function, the whole instantiation
+         * should be done at that position. But, immediate running semantic3 of
+         * dependent templates may cause unresolved forward reference (Bugzilla 9050).
+         * To avoid the issue, don't run semantic3 until semantic and semantic2 done.
+         */
+        TemplateInstances deferred;
+        this->deferred = &deferred;
+
+        //printf("Run semantic3 on %s\n", toChars());
         trySemantic3(sc2);
+
+        for (size_t i = 0; i < deferred.dim; i++)
+        {
+            //printf("+ run deferred semantic3 on %s\n", deferred[i]->toChars());
+            deferred[i]->semantic3(NULL);
+        }
+
+        this->deferred = NULL;
+    }
+    else if (tinst)
+    {
+        TemplateInstance *ti = tinst;
+        int nest = 0;
+        while (ti && !ti->deferred && ti->tinst)
+        {
+            ti = ti->tinst;
+            if (++nest > 500)
+            {
+                global.gag = 0;            // ensure error message gets printed
+                error("recursive expansion");
+                fatal();
+            }
+        }
+        if (ti && ti->deferred)
+        {
+            //printf("deferred semantic3 of %p %s, ti = %s, ti->deferred = %p\n", this, toChars(), ti->toChars());
+            for (size_t i = 0; ; i++)
+            {
+                if (i == ti->deferred->dim)
+                {
+                    ti->deferred->push(this);
+                    break;
+                }
+                if ((*ti->deferred)[i] == this)
+                    break;
+            }
+        }
     }
 
   Laftersemantic:

src/template.h

@@ -315,6 +315,8 @@ class TemplateInstance : public ScopeDsymbol
     Expressions *fargs;                 // for function template, these are the function arguments
     Module *instantiatingModule;        // the top module that instantiated this instance
 
+    TemplateInstances* deferred;
+
     TemplateInstance(Loc loc, Identifier *temp_id);
     TemplateInstance(Loc loc, TemplateDeclaration *tempdecl, Objects *tiargs);
     static Objects *arraySyntaxCopy(Objects *objs);

test/runnable/template9.d

@@ -1913,6 +1913,42 @@ void test9038()
     check_data9038!(bar.f)(bar);
 }
 
+/**********************************/
+// 9050
+
+struct A9050(T) {}
+
+struct B9050(T)
+{
+    void f() { foo9050(A9050!int()); }
+}
+
+auto foo9050()(A9050!int base) pure
+{
+    return B9050!int();
+}
+
+auto s9050 = foo9050(A9050!int());
+
+/**********************************/
+// 10936 (dup of 9050)
+
+struct Vec10936(string s)
+{
+    auto foo(string v)()
+    {
+        return Vec10936!(v)();
+    }
+
+    static void bar()
+    {
+        Vec10936!"" v;
+        auto p = v.foo!"sup";
+    }
+}
+
+Vec10936!"" v;
+
 /**********************************/
 // 9076