fix Issue 23598 - Circular reference bug with static if and eponymous templates (#14838)

compiler/src/dmd/attrib.d

@@ -207,7 +207,7 @@ extern (C++) abstract class AttribDeclaration : Dsymbol
         objc.addSymbols(this, classes, categories);
     }
 
-    override final inout(AttribDeclaration) isAttribDeclaration() inout pure @safe
+    override inout(AttribDeclaration) isAttribDeclaration() inout pure @safe
     {
         return this;
     }
@@ -1080,6 +1080,11 @@ extern (C++) final class StaticIfDeclaration : ConditionalDeclaration
         return "static if";
     }
 
+    override inout(StaticIfDeclaration) isStaticIfDeclaration() inout pure @safe
+    {
+        return this;
+    }
+
     override void accept(Visitor v)
     {
         v.visit(this);

compiler/src/dmd/attrib.h

@@ -37,7 +37,7 @@ public:
     bool hasStaticCtorOrDtor() override final;
     void checkCtorConstInit() override final;
     void addLocalClass(ClassDeclarations *) override final;
-    AttribDeclaration *isAttribDeclaration() override final { return this; }
+    AttribDeclaration *isAttribDeclaration() override { return this; }
 
     void accept(Visitor *v) override { v->visit(this); }
 };
@@ -184,6 +184,7 @@ public:
     void addMember(Scope *sc, ScopeDsymbol *sds) override;
     void setScope(Scope *sc) override;
     void importAll(Scope *sc) override;
+    StaticIfDeclaration *isStaticIfDeclaration() override { return this; }
     const char *kind() const override;
     void accept(Visitor *v) override { v->visit(this); }
 };

compiler/src/dmd/dsymbol.d

@@ -1413,6 +1413,7 @@ extern (C++) class Dsymbol : ASTNode
     inout(OverloadSet)                 isOverloadSet()                 inout { return null; }
     inout(CompileDeclaration)          isCompileDeclaration()          inout { return null; }
     inout(StaticAssert)                isStaticAssert()                inout { return null; }
+    inout(StaticIfDeclaration)         isStaticIfDeclaration()         inout { return null; }
 }
 
 /***********************************************************

compiler/src/dmd/dsymbol.h

@@ -72,6 +72,7 @@ class ExpressionDsymbol;
 class AliasAssign;
 class OverloadSet;
 class StaticAssert;
+class StaticIfDeclaration;
 struct AA;
 #ifdef IN_GCC
 typedef union tree_node Symbol;
@@ -323,6 +324,7 @@ public:
     virtual OverloadSet *isOverloadSet() { return NULL; }
     virtual CompileDeclaration *isCompileDeclaration() { return NULL; }
     virtual StaticAssert *isStaticAssert() { return NULL; }
+    virtual StaticIfDeclaration *isStaticIfDeclaration() { return NULL; }
     void accept(Visitor *v) override { v->visit(this); }
 };
 

compiler/src/dmd/dsymbolsem.d

@@ -4539,7 +4539,8 @@ private extern(C++) final class DsymbolSemanticVisitor : Visitor
 
     override void visit(StructDeclaration sd)
     {
-        //printf("StructDeclaration::semantic(this=%p, '%s', sizeok = %d)\n", sd, sd.toPrettyChars(), sd.sizeok);
+        enum log = false;
+        if (log) printf("+StructDeclaration::semantic(this=%p, '%s', sizeok = %d)\n", sd, sd.toPrettyChars(), sd.sizeok);
 
         //static int count; if (++count == 20) assert(0);
 
@@ -4609,6 +4610,7 @@ private extern(C++) final class DsymbolSemanticVisitor : Visitor
 
         if (!sd.members) // if opaque declaration
         {
+            if (log) printf("\topaque declaration %s\n", sd.toChars());
             sd.semanticRun = PASS.semanticdone;
             return;
         }
@@ -4660,7 +4662,7 @@ private extern(C++) final class DsymbolSemanticVisitor : Visitor
 
             sc2.pop();
 
-            //printf("\tdeferring %s\n", toChars());
+            if (log) printf("\tdeferring %s\n", sd.toChars());
             return deferDsymbolSemantic(sd, scx);
         }
 
@@ -4690,7 +4692,7 @@ private extern(C++) final class DsymbolSemanticVisitor : Visitor
         sd.inv = buildInv(sd, sc2);
 
         sd.semanticRun = PASS.semanticdone;
-        //printf("-StructDeclaration::semantic(this=%p, '%s')\n", sd, sd.toChars());
+        if (log) printf("-StructDeclaration::semantic(this=%p, '%s', sizeok = %d)\n", sd, sd.toPrettyChars(), sd.sizeok);
 
         sc2.pop();
 
@@ -4757,6 +4759,7 @@ private extern(C++) final class DsymbolSemanticVisitor : Visitor
         // Make an error in 2.110
         if (sd.storage_class & STC.scope_)
             deprecation(sd.loc, "`scope` as a type constraint is deprecated.  Use `scope` at the usage site.");
+        //printf("-StructDeclaration::semantic(this=%p, '%s', sizeok = %d)\n", sd, sd.toPrettyChars(), sd.sizeok);
     }
 
     void interfaceSemantic(ClassDeclaration cd)
@@ -6147,7 +6150,7 @@ void templateInstanceSemantic(TemplateInstance tempinst, Scope* sc, Expressions*
         Dsymbol s;
         if (Dsymbol.oneMembers(tempinst.members, &s, tempdecl.ident) && s)
         {
-            //printf("tempdecl.ident = %s, s = '%s'\n", tempdecl.ident.toChars(), s.kind(), s.toPrettyChars());
+            //printf("tempdecl.ident = %s, s = `%s %s`\n", tempdecl.ident.toChars(), s.kind(), s.toPrettyChars());
             //printf("setting aliasdecl\n");
             tempinst.aliasdecl = s;
         }
@@ -6194,7 +6197,7 @@ void templateInstanceSemantic(TemplateInstance tempinst, Scope* sc, Expressions*
         {
             if (!tempinst.aliasdecl || tempinst.aliasdecl != s)
             {
-                //printf("tempdecl.ident = %s, s = '%s'\n", tempdecl.ident.toChars(), s.kind(), s.toPrettyChars());
+                //printf("tempdecl.ident = %s, s = `%s %s`\n", tempdecl.ident.toChars(), s.kind(), s.toPrettyChars());
                 //printf("setting aliasdecl 2\n");
                 tempinst.aliasdecl = s;
             }

compiler/src/dmd/dtemplate.d

@@ -45,6 +45,7 @@ import dmd.aliasthis;
 import dmd.arraytypes;
 import dmd.astenums;
 import dmd.ast_node;
+import dmd.attrib;
 import dmd.dcast;
 import dmd.dclass;
 import dmd.declaration;
@@ -1226,7 +1227,7 @@ extern (C++) final class TemplateDeclaration : ScopeDsymbol
         paramscope.pop();
         static if (LOGM)
         {
-            printf("-TemplateDeclaration.matchWithInstance(this = %p, ti = %p) = %d\n", this, ti, m);
+            printf("-TemplateDeclaration.matchWithInstance(this = %s, ti = %s) = %d\n", toChars(), ti.toChars(), m);
         }
         return m;
     }
@@ -7520,6 +7521,43 @@ extern (C++) class TemplateInstance : ScopeDsymbol
 
         members.foreachDsymbol( (s) { s.importAll(sc2); } );
 
+        if (!aliasdecl)
+        {
+            /* static if's are crucial to evaluating aliasdecl correctly. But
+             * evaluating the if/else bodies may require aliasdecl.
+             * So, evaluate the condition for static if's, but not their if/else bodies.
+             * Then try to set aliasdecl.
+             * Later do the if/else bodies.
+             * https://issues.dlang.org/show_bug.cgi?id=23598
+             * It might be better to do this by attaching a lambda to the StaticIfDeclaration
+             * to do the oneMembers call after the sid.include(sc2) is run as part of dsymbolSemantic().
+             */
+            bool done;
+            void staticIfDg(Dsymbol s)
+            {
+                if (done || aliasdecl)
+                    return;
+                //printf("\t staticIfDg on '%s %s' in '%s'\n",  s.kind(), s.toChars(), this.toChars());
+                if (!s.isStaticIfDeclaration())
+                {
+		    //s.dsymbolSemantic(sc2);
+                    done = true;
+                    return;
+                }
+                auto sid = s.isStaticIfDeclaration();
+                sid.include(sc2);
+                if (members.length)
+                {
+                    Dsymbol sa;
+                    if (Dsymbol.oneMembers(members, &sa, tempdecl.ident) && sa)
+                        aliasdecl = sa;
+                }
+                done = true;
+            }
+
+            members.foreachDsymbol(&staticIfDg);
+        }
+
         void symbolDg(Dsymbol s)
         {
             //printf("\t semantic on '%s' %p kind %s in '%s'\n",  s.toChars(), s, s.kind(), this.toChars());

compiler/src/dmd/frontend.h

@@ -102,6 +102,7 @@ class VisibilityDeclaration;
 class OverloadSet;
 class CompileDeclaration;
 class StaticAssert;
+class StaticIfDeclaration;
 class DsymbolTable;
 struct MangleOverride;
 class AliasThis;
@@ -571,6 +572,7 @@ public:
     virtual OverloadSet* isOverloadSet();
     virtual CompileDeclaration* isCompileDeclaration();
     virtual StaticAssert* isStaticAssert();
+    virtual StaticIfDeclaration* isStaticIfDeclaration();
 };
 
 typedef uint64_t size_t;
@@ -5387,7 +5389,7 @@ public:
     void checkCtorConstInit() final override;
     void addLocalClass(Array<ClassDeclaration* >* aclasses) final override;
     void addObjcSymbols(Array<ClassDeclaration* >* classes, Array<ClassDeclaration* >* categories) final override;
-    AttribDeclaration* isAttribDeclaration() final override;
+    AttribDeclaration* isAttribDeclaration() override;
     void accept(Visitor* v) override;
 };
 
@@ -5524,6 +5526,7 @@ public:
     void setScope(Scope* sc) override;
     void importAll(Scope* sc) override;
     const char* kind() const override;
+    StaticIfDeclaration* isStaticIfDeclaration() override;
     void accept(Visitor* v) override;
 };
 

compiler/test/compilable/test23598.d

@@ -0,0 +1,87 @@
+// https://issues.dlang.org/show_bug.cgi?id=23598
+
+alias AliasSeq(a...) = a;
+
+static if (1)
+{
+
+template sort(alias f, a...)
+{
+    static if (a.length > 0)
+    {
+        alias x = f!(a[0]);
+        alias sort = a;
+    }
+    else
+        alias sort = a;
+}
+
+alias SortedItems = sort!(isDependencyOf, String);
+
+enum isDependencyOf(Item) = Item.DirectDependencies.length == 0;
+
+struct String
+{
+    alias DirectDependencies = AliasSeq!();
+
+    enum l = SortedItems.length; // (3)
+}
+
+}
+
+/*****************************************************/
+
+static if (1)
+{
+enum x = 1;
+enum y = 2;
+
+template f(T)
+{
+    alias b = int;
+    static if (x)
+    {
+        alias c = x;
+    }
+    else
+    {
+        alias c = y;
+    }
+
+    static if (is(typeof(c)))
+    {
+    }
+    else
+    {
+        static assert(0);
+    }
+}
+
+void g()
+{
+    int x = f!int.c;
+}
+}
+
+/*****************************************************/
+
+template forward(args...)
+{
+    template fwd(alias arg)
+    {
+        alias fwd = arg;
+    }
+
+    alias Result = AliasSeq!();
+    static foreach (arg; args)
+        Result = AliasSeq!(Result, fwd!arg);
+    static if (Result.length == 1)
+        alias forward = Result[0];
+    else
+        alias forward = Result;
+}
+
+void func(int i, int j)
+{
+    func(forward!(i, j));
+}

compiler/test/fail_compilation/ice12727.d

@@ -1,13 +1,13 @@
 /*
 TEST_OUTPUT:
 ----
+fail_compilation/ice12727.d(16): Error: template instance `IndexTuple!(1, 0)` recursive template expansion
 fail_compilation/ice12727.d(16): Error: alias `ice12727.IndexTuple!(1, 0).IndexTuple` recursive alias declaration
 fail_compilation/ice12727.d(23): Error: template instance `ice12727.IndexTuple!(1, 0)` error instantiating
 fail_compilation/ice12727.d(27):        instantiated from here: `Matrix!(float, 3)`
 fail_compilation/ice12727.d(28):        instantiated from here: `Vector!(float, 3)`
 ----
 */
-
 template IndexTuple(int e, int s = 0, T...)
 {
     static if (s == e)

compiler/test/fail_compilation/ice13816.d

@@ -1,11 +1,13 @@
 /*
 TEST_OUTPUT:
 ---
-fail_compilation/ice13816.d(15): Error: alias `ice13816.ItemProperty!().ItemProperty` recursive alias declaration
-fail_compilation/ice13816.d(20): Error: template instance `ice13816.ItemProperty!()` error instantiating
+fail_compilation/ice13816.d(17): Error: template instance `TypeTuple!(ItemProperty!())` recursive template expansion
+fail_compilation/ice13816.d(17): Error: alias `ice13816.ItemProperty!().ItemProperty` recursive alias declaration
+fail_compilation/ice13816.d(22): Error: template instance `ice13816.ItemProperty!()` error instantiating
 ---
 */
 
+
 alias TypeTuple(T...) = T;
 
 template ItemProperty()