From 61076ac6de10357195e32481613c3b80dd900550 Mon Sep 17 00:00:00 2001
From: Sander Mertens <sander.mertens8@gmail.com>
Date: Thu, 3 Aug 2023 16:49:33 -0700
Subject: [PATCH] #1016 allow meta computed alignment to be smaller than actual
 alignment

---
 flecs.c                     | 13 +++++++---
 src/addons/meta/meta.c      | 13 +++++++---
 test/meta/project.json      |  3 ++-
 test/meta/src/StructTypes.c | 51 +++++++++++++++++++++++++++++++++++++
 test/meta/src/main.c        |  7 ++++-
 5 files changed, 77 insertions(+), 10 deletions(-)

diff --git a/flecs.c b/flecs.c
index ffc4a4b5a3..cd1f6e96c1 100644
--- a/flecs.c
+++ b/flecs.c
@@ -25274,10 +25274,15 @@ int flecs_init_type(
             return -1;
         }
         if (comp->size == size && comp->alignment != alignment) {
-            ecs_err("computed size for '%s' matches with actual type but "
-                "alignment is different (%d vs. %d)", ecs_get_name(world, type),
-                    alignment, comp->alignment);
-            return -1;
+            if (comp->alignment < alignment) {
+                ecs_err("computed size for '%s' matches with actual type but "
+                    "alignment is different (%d vs. %d)", ecs_get_name(world, type),
+                        alignment, comp->alignment);
+            } else {
+                /* If this is an existing type, the alignment can be larger but
+                 * not smaller than the computed alignment. */
+                alignment = comp->alignment;
+            }
         }
         
         meta_type->partial = comp->size != size;
diff --git a/src/addons/meta/meta.c b/src/addons/meta/meta.c
index b6e4cc0a88..580c502768 100644
--- a/src/addons/meta/meta.c
+++ b/src/addons/meta/meta.c
@@ -295,10 +295,15 @@ int flecs_init_type(
             return -1;
         }
         if (comp->size == size && comp->alignment != alignment) {
-            ecs_err("computed size for '%s' matches with actual type but "
-                "alignment is different (%d vs. %d)", ecs_get_name(world, type),
-                    alignment, comp->alignment);
-            return -1;
+            if (comp->alignment < alignment) {
+                ecs_err("computed size for '%s' matches with actual type but "
+                    "alignment is different (%d vs. %d)", ecs_get_name(world, type),
+                        alignment, comp->alignment);
+            } else {
+                /* If this is an existing type, the alignment can be larger but
+                 * not smaller than the computed alignment. */
+                alignment = comp->alignment;
+            }
         }
         
         meta_type->partial = comp->size != size;
diff --git a/test/meta/project.json b/test/meta/project.json
index b392ede1f1..0340a1a173 100644
--- a/test/meta/project.json
+++ b/test/meta/project.json
@@ -120,7 +120,8 @@
                 "invalid_warning_range",
                 "overlapping_error_warning_range",
                 "overlapping_value_error_range",
-                "overlapping_value_warning_range"
+                "overlapping_value_warning_range",
+                "struct_w_16_alignment"
             ]
         }, {
             "id": "NestedStructTypes",
diff --git a/test/meta/src/StructTypes.c b/test/meta/src/StructTypes.c
index d735dae0e3..ef2353cb62 100644
--- a/test/meta/src/StructTypes.c
+++ b/test/meta/src/StructTypes.c
@@ -771,3 +771,54 @@ void StructTypes_overlapping_value_warning_range() {
 
     ecs_fini(world);
 }
+
+void StructTypes_struct_w_16_alignment() {
+#ifndef _MSC_VER
+    typedef __attribute((aligned(16)))
+#else
+    typedef __declspec(align(16))
+#endif
+    struct T {
+        float x;
+        float y;
+        float z;
+        float w;
+    } T;
+
+    ecs_world_t *world = ecs_init();
+
+    ECS_COMPONENT(world, T);
+
+    ecs_entity_t t = ecs_struct(world, {
+        .entity = ecs_id(T),
+        .members = {
+            {"x", ecs_id(ecs_f32_t)},
+            {"y", ecs_id(ecs_f32_t)},
+            {"z", ecs_id(ecs_f32_t)},
+            {"w", ecs_id(ecs_f32_t)}
+        }
+    });
+
+    test_assert(t != 0);
+    test_str(ecs_get_name(world, t), "T");
+
+    meta_test_struct(world, t, T);
+    meta_test_member(world, t, T, x, ecs_id(ecs_f32_t), 1);
+    meta_test_member(world, t, T, y, ecs_id(ecs_f32_t), 1);
+    meta_test_member(world, t, T, z, ecs_id(ecs_f32_t), 1);
+    meta_test_member(world, t, T, w, ecs_id(ecs_f32_t), 1);
+
+    const EcsComponent *cptr = ecs_get(world, t, EcsComponent);
+    test_assert(cptr != NULL);
+    test_int(cptr->size, sizeof(T));
+    test_int(cptr->alignment, 16);
+
+    const EcsMetaType *mptr = ecs_get(world, t, EcsMetaType);
+    test_assert(mptr != NULL);
+    test_bool(mptr->partial, false);
+    test_bool(mptr->existing, true);
+    test_int(mptr->size, sizeof(T));
+    test_int(mptr->alignment, 16);
+
+    ecs_fini(world);
+}
diff --git a/test/meta/src/main.c b/test/meta/src/main.c
index 43700d81e8..e4ac1962a8 100644
--- a/test/meta/src/main.c
+++ b/test/meta/src/main.c
@@ -110,6 +110,7 @@ void StructTypes_invalid_warning_range(void);
 void StructTypes_overlapping_error_warning_range(void);
 void StructTypes_overlapping_value_error_range(void);
 void StructTypes_overlapping_value_warning_range(void);
+void StructTypes_struct_w_16_alignment(void);
 
 // Testsuite 'NestedStructTypes'
 void NestedStructTypes_1_bool(void);
@@ -1345,6 +1346,10 @@ bake_test_case StructTypes_testcases[] = {
     {
         "overlapping_value_warning_range",
         StructTypes_overlapping_value_warning_range
+    },
+    {
+        "struct_w_16_alignment",
+        StructTypes_struct_w_16_alignment
     }
 };
 
@@ -4679,7 +4684,7 @@ static bake_test_suite suites[] = {
         "StructTypes",
         NULL,
         NULL,
-        27,
+        28,
         StructTypes_testcases
     },
     {