d/dmd: Merge upstream dmd 39edbe17e

Backported fix from upstream dmd 2.079 for an internal compiler error
that occurred during semantic analysis on a recursive field initializer.

Fixes https://gcc.gnu.org/PR88989

Reviewed-on: https://github.com/dlang/dmd/pull/9284

From-SVN: r268740

gcc/d/dmd/MERGE

-e21c07e84bd9668e1c0fc1f45e514c5fd76988e7
+39edbe17e7b5c761d780c9d1d4376a06df7bf3d8
 
 The first line of this file holds the git revision number of the last
 merge done from the dlang/dmd repository.

gcc/d/dmd/dstruct.c

@@ -723,6 +723,13 @@ bool AggregateDeclaration::fill(Loc loc, Expressions *elements, bool ctorinit)
             else if (vx->_init)
             {
                 assert(!vx->_init->isVoidInitializer());
+                if (vx->inuse)   // https://issues.dlang.org/show_bug.cgi?id=18057
+                {
+                    vx->error(loc, "recursive initialization of field");
+                    errors = true;
+                    e = NULL;
+                }
+                else
                     e = vx->getConstInitializer(false);
             }
             else

gcc/testsuite/gdc.test/compilable/interpret3.d

@@ -7731,3 +7731,14 @@ bool foo17407()
 
 static assert(!foo17407);
 
+/**************************************************/
+// https://issues.dlang.org/show_bug.cgi?id=18057
+// Recursive field initializer causes segfault.
+
+struct RBNode(T)
+{
+    RBNode!T *copy = new RBNode!T;
+}
+
+static assert(!__traits(compiles, { alias bug18057 = RBNode!int; }));
+

gcc/testsuite/gdc.test/fail_compilation/fail18057.d

+/**
+TEST_OUTPUT:
+---
+fail_compilation/fail18057.d(16): Error: template instance RBNode!int `RBNode` is not a template declaration, it is a struct
+fail_compilation/fail18057.d(13): Error: variable fail18057.RBNode.copy recursive initialization of field
+---
+*/
+
+// https://issues.dlang.org/show_bug.cgi?id=18057
+// Recursive field initializer causes segfault.
+struct RBNode
+{
+    RBNode *copy = new RBNode;
+}
+
+alias bug18057 = RBNode!int;

gcc/testsuite/gdc.test/fail_compilation/fail18057b.d

+/**
+TEST_OUTPUT:
+---
+fail_compilation/fail18057b.d(12): Error: variable `fail18057b.Recursive.field` recursive initialization of field
+---
+*/
+
+// https://issues.dlang.org/show_bug.cgi?id=18057
+// Recursive field initializer causes segfault.
+struct Recursive
+{
+    int field = Recursive();
+}