fix fix Issue 12231 - ICE on the class declaration within lambda insi…

…de template constraint

src/expression.c

@@ -5477,12 +5477,13 @@ void FuncExp::genIdent(Scope *sc)
         DsymbolTable *symtab;
         if (FuncDeclaration *func = sc->parent->isFuncDeclaration())
         {
-            symtab = func->localsymtab;
-            if (symtab)
+            if (func->localsymtab == NULL)
             {
                 // Inside template constraint, symtab is not set yet.
-                goto L1;
+                // Initialize it lazily.
+                func->localsymtab = new DsymbolTable();
             }
+            symtab = func->localsymtab;
         }
         else
         {
@@ -5496,9 +5497,7 @@ void FuncExp::genIdent(Scope *sc)
             }
             symtab = sds->symtab;
         }
-        if (!symtab)
-            return;
-    L1:
+        assert(symtab);
         int num = (int)_aaLen(symtab->tab) + 1;
         Identifier *id = Lexer::uniqueId(s, num);
         fd->ident = id;

src/template.c

@@ -806,11 +806,13 @@ bool TemplateDeclaration::evaluateConstraint(
     scx = scx->startCTFE();
     scx->flags |= SCOPEstaticif;
     assert(ti->inst == NULL);
+    ti->inst = ti;  // temporary instantiation to enable genIdent()
 
     //printf("\tscx->parent = %s %s\n", scx->parent->kind(), scx->parent->toPrettyChars());
     e = e->semantic(scx);
     e = resolveProperties(scx, e);
 
+    ti->inst = NULL;
     ti->symtab = NULL;
     scx = scx->endCTFE();
 
@@ -971,6 +973,7 @@ MATCH TemplateDeclaration::matchWithInstance(Scope *sc, TemplateInstance *ti,
             // Resolve parameter types and 'auto ref's.
             tf->fargs = fargs;
             fd->type = tf->semantic(loc, paramscope);
+            fd->originalType = fd->type;    // for mangling
             if (fd->type->ty != Tfunction)
                 goto Lnomatch;
         }
@@ -2600,6 +2603,7 @@ FuncDeclaration *TemplateDeclaration::doHeaderInstantiation(
     fd->type = tf;
     fd->type = fd->type->addSTC(scx->stc);
     fd->type = fd->type->semantic(fd->loc, scx);
+    fd->originalType = fd->type;    // for mangling
     //printf("\t[%s] fd->type = %s, mod = %x, ", loc.toChars(), fd->type->toChars(), fd->type->mod);
     //printf("fd->needThis() = %d\n", fd->needThis());
 
@@ -7090,7 +7094,13 @@ Identifier *TemplateInstance::genIdent(Objects *args)
     //printf("TemplateInstance::genIdent('%s')\n", tempdecl->ident->toChars());
     OutBuffer buf;
     char *id = tempdecl->ident->toChars();
-    buf.printf("__T%llu%s", (ulonglong)strlen(id), id);
+    if (!members)
+    {
+        // Use "__U" for the symbols declared inside template constraint.
+        buf.printf("__U%llu%s", (ulonglong)strlen(id), id);
+    }
+    else
+        buf.printf("__T%llu%s", (ulonglong)strlen(id), id);
     for (size_t i = 0; i < args->dim; i++)
     {
         RootObject *o = (*args)[i];

src/toobj.c

@@ -1161,24 +1161,6 @@ void TemplateInstance::toObjFile(int multiobj)
 #endif
     if (!isError(this) && members)
     {
-        FuncDeclaration *fd = enclosing ? enclosing->isFuncDeclaration() : NULL;
-        if (fd && fd->fbody == NULL)
-        {
-            /* Prevent codegen if enclosing is an artificially instantiated function.
-             */
-            return;
-        }
-
-        TemplateDeclaration *tempdecl = this->tempdecl->isTemplateDeclaration();
-        assert(tempdecl);
-        if (tempdecl->literal && tempdecl->ident == Id::empty)
-        {
-            /* Bugzilla 10313: Template lambdas that instantiated in template constraint
-             * cannot appear in runnable code block. So, this skip won't cause linker failure.
-             */
-            return;
-        }
-
         if (multiobj)
             // Append to list of object files to be written later
             obj_append(this);

test/runnable/mangle.d

@@ -393,6 +393,75 @@ void test12217(int)
 
 void test12217() {}
 
+/***************************************************/
+// 12231
+
+void func12231a()()
+if (is(typeof({
+        class C {}
+        static assert(C.mangleof ==
+            "C6mangle16__U10func12231aZ10func12231aFZ9__lambda1MFZ1C");
+            //         ###            L                       #
+    })))
+{}
+
+void func12231b()()
+if (is(typeof({
+        class C {}
+        static assert(C.mangleof ==
+            "C6mangle16__U10func12231bZ10func12231bFZ9__lambda1MFZ1C");
+            //         L__L           L                       LL
+    })) &&
+    is(typeof({
+        class C {}
+        static assert(C.mangleof ==
+            "C6mangle16__U10func12231bZ10func12231bFZ9__lambda2MFZ1C");
+            //         L__L           L                       LL
+    })))
+{}
+
+void func12231c()()
+if (is(typeof({
+        class C {}
+        static assert(C.mangleof ==
+            "C6mangle16__U10func12231cZ10func12231cFZ9__lambda1MFZ1C");
+            //         L__L           L                       LL
+    })))
+{
+    (){
+        class C {}
+        static assert(C.mangleof ==
+            "C6mangle16__T10func12231cZ10func12231cFZ9__lambda1MFZ1C");
+            //         L__L           L                       LL
+    }();
+}
+
+void func12231c(X)()
+if (is(typeof({
+        class C {}
+        static assert(C.mangleof ==
+            "C6mangle20__U10func12231cTAyaZ10func12231cFZ9__lambda1MFZ1C");
+            //         L__L           L___L                       LL
+    })))
+{
+    (){
+        class C {}
+        static assert(C.mangleof ==
+            "C6mangle20__T10func12231cTAyaZ10func12231cFZ9__lambda1MFZ1C");
+            //         L__L           L___L                       LL
+    }();
+}
+
+void test12231()
+{
+    func12231a();
+
+    func12231b();
+
+    func12231c();
+    func12231c!string();
+}
+
 /***************************************************/
 
 void main()