From c6c3ed60276b842114aefce54d73e30e578fdd6d Mon Sep 17 00:00:00 2001
From: Iain Buclaw <ibuclaw@gdcproject.org>
Date: Wed, 9 Jun 2021 19:37:22 +0200
Subject: [PATCH] d: Respect explicit align(N) type alignment (PR100935)

It was previously the natural type alignment, defined as the maximum of
the field alignments for an aggregate.  Make sure an explicit align(N)
overrides it.

gcc/d/ChangeLog:

	PR d/100935
	* dmd/mtype.c (Type::getProperty): Prefer explicit alignment over
	natural alignment for alignof property.

gcc/testsuite/ChangeLog:

	PR d/100935
	* gdc.test/compilable/aggr_alignment.d: Add test cases.

(cherry picked from commit 04fea2d66bd680beb1a204e62f2f459307000813)
---
 gcc/d/dmd/mtype.c                             |  5 ++++-
 .../gdc.test/compilable/aggr_alignment.d      | 20 +++++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/gcc/d/dmd/mtype.c b/gcc/d/dmd/mtype.c
index 9ef8ab4e5f48..6cccf40df986 100644
--- a/gcc/d/dmd/mtype.c
+++ b/gcc/d/dmd/mtype.c
@@ -2040,7 +2040,10 @@ Expression *Type::getProperty(Loc loc, Identifier *ident, int flag)
     }
     else if (ident == Id::__xalignof)
     {
-        e = new IntegerExp(loc, alignsize(), Type::tsize_t);
+        unsigned explicitAlignment = alignment();
+        unsigned naturalAlignment = alignsize();
+        unsigned actualAlignment = (explicitAlignment == STRUCTALIGN_DEFAULT ? naturalAlignment : explicitAlignment);
+        e = new IntegerExp(loc, actualAlignment, Type::tsize_t);
     }
     else if (ident == Id::_init)
     {
diff --git a/gcc/testsuite/gdc.test/compilable/aggr_alignment.d b/gcc/testsuite/gdc.test/compilable/aggr_alignment.d
index bf602ff31a47..0c727e2fec56 100644
--- a/gcc/testsuite/gdc.test/compilable/aggr_alignment.d
+++ b/gcc/testsuite/gdc.test/compilable/aggr_alignment.d
@@ -27,6 +27,26 @@ static assert(C2.int1.offsetof == payloadOffset + 8);
 static assert(C2.alignof == size_t.sizeof);
 static assert(__traits(classInstanceSize, C2) == payloadOffset + 12);
 
+align(8) struct PaddedStruct
+{
+    bool flag;
+    align(2) S1 s1;
+}
+
+static assert(PaddedStruct.s1.offsetof == 2);
+static assert(PaddedStruct.alignof == 8);
+static assert(PaddedStruct.sizeof == 16);
+
+align(1) struct UglyStruct
+{
+    bool flag;
+    int i;
+    ubyte u;
+}
+
+static assert(UglyStruct.i.offsetof == 4);
+static assert(UglyStruct.alignof == 1);
+static assert(UglyStruct.sizeof == 9);
 
 /***************************************************/
 // https://issues.dlang.org/show_bug.cgi?id=19914
-- 
2.47.2