From eacfafbc3534fb32782934d765d21855dff32e56 Mon Sep 17 00:00:00 2001
From: Iain Buclaw <ibuclaw@gdcproject.org>
Date: Tue, 23 Jun 2020 14:45:50 +0200
Subject: [PATCH] d: Don't set DECL_INITIAL if initializer is 'void'.

Declarations initialized with `= void` were being default initialized.
That is not really the intent, and misses the small optimization that
should have been gained from using void initializations.

gcc/d/ChangeLog:

	* decl.cc (DeclVisitor::visit (VarDeclaration *)): Don't set
	DECL_INITIAL if initializer is 'void'.

gcc/testsuite/ChangeLog:

	* gdc.dg/init1.d: New test.
---
 gcc/d/decl.cc                | 11 ++++++++---
 gcc/testsuite/gdc.dg/init1.d |  9 +++++++++
 2 files changed, 17 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gdc.dg/init1.d

diff --git a/gcc/d/decl.cc b/gcc/d/decl.cc
index ea6614fb714..77144fe11c8 100644
--- a/gcc/d/decl.cc
+++ b/gcc/d/decl.cc
@@ -697,13 +697,18 @@ public:
 	    return;
 	  }
 
-	if (d->_init && !d->_init->isVoidInitializer ())
+	if (d->_init)
 	  {
-	    Expression *e = initializerToExpression (d->_init, d->type);
-	    DECL_INITIAL (decl) = build_expr (e, true);
+	    /* Use the explicit initializer, this includes `void`.  */
+	    if (!d->_init->isVoidInitializer ())
+	      {
+		Expression *e = initializerToExpression (d->_init, d->type);
+		DECL_INITIAL (decl) = build_expr (e, true);
+	      }
 	  }
 	else
 	  {
+	    /* Use default initializer for the type.  */
 	    if (TypeStruct *ts = d->type->isTypeStruct ())
 	      DECL_INITIAL (decl) = layout_struct_initializer (ts->sym);
 	    else
diff --git a/gcc/testsuite/gdc.dg/init1.d b/gcc/testsuite/gdc.dg/init1.d
new file mode 100644
index 00000000000..679ad15460e
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/init1.d
@@ -0,0 +1,9 @@
+// { dg-do run { target hw } }
+// { dg-options "-fno-druntime" }
+// 'a' should not be default initialized to -1.
+static char a = void;
+
+extern (C) void main()
+{
+    assert(a == 0);
+}
-- 
2.30.2