diff --git a/tests/debuginfo/associated-types.rs b/tests/debuginfo/associated-types.rs
index f61e76cbe5997..1f07c0e29dea1 100644
--- a/tests/debuginfo/associated-types.rs
+++ b/tests/debuginfo/associated-types.rs
@@ -82,6 +82,7 @@ impl TraitWithAssocType for i32 {
     fn get_value(&self) -> i64 { *self as i64 }
 }
 
+#[repr(C)]
 struct Struct<T: TraitWithAssocType> {
     b: T,
     b1: T::Type,
diff --git a/tests/debuginfo/boxed-struct.rs b/tests/debuginfo/boxed-struct.rs
index 03897177959eb..9d2460639805f 100644
--- a/tests/debuginfo/boxed-struct.rs
+++ b/tests/debuginfo/boxed-struct.rs
@@ -25,6 +25,7 @@
 
 #![allow(unused_variables)]
 
+#[repr(C)]
 struct StructWithSomePadding {
     x: i16,
     y: i32,
@@ -32,6 +33,7 @@ struct StructWithSomePadding {
     w: i64
 }
 
+#[repr(C)]
 struct StructWithDestructor {
     x: i16,
     y: i32,
diff --git a/tests/debuginfo/c-style-enum-in-composite.rs b/tests/debuginfo/c-style-enum-in-composite.rs
index 6839c07cd55a5..6ae3c3bcdd572 100644
--- a/tests/debuginfo/c-style-enum-in-composite.rs
+++ b/tests/debuginfo/c-style-enum-in-composite.rs
@@ -57,18 +57,21 @@
 use self::AnEnum::{OneHundred, OneThousand, OneMillion};
 use self::AnotherEnum::{MountainView, Toronto, Vienna};
 
+#[repr(u32)]
 enum AnEnum {
     OneHundred = 100,
     OneThousand = 1000,
     OneMillion = 1000000
 }
 
+#[repr(u8)]
 enum AnotherEnum {
     MountainView,
     Toronto,
     Vienna
 }
 
+#[repr(C)]
 struct PaddedStruct {
     a: i16,
     b: AnEnum,
@@ -77,7 +80,7 @@ struct PaddedStruct {
     e: i16
 }
 
-#[repr(packed)]
+#[repr(C, packed)]
 struct PackedStruct {
     a: i16,
     b: AnEnum,
@@ -86,6 +89,7 @@ struct PackedStruct {
     e: i16
 }
 
+#[repr(C)]
 struct NonPaddedStruct {
     a: AnEnum,
     b: AnotherEnum,
diff --git a/tests/debuginfo/destructured-for-loop-variable.rs b/tests/debuginfo/destructured-for-loop-variable.rs
index b8cde881b9ce6..13395f5e407a4 100644
--- a/tests/debuginfo/destructured-for-loop-variable.rs
+++ b/tests/debuginfo/destructured-for-loop-variable.rs
@@ -73,6 +73,8 @@
 // === LLDB TESTS ==================================================================================
 
 //@ lldb-command:type format add --format hex char
+// MSVC uses signed char
+//@ lldb-command:type format add --format hex 'signed char'
 //@ lldb-command:type format add --format hex 'unsigned char'
 
 //@ lldb-command:run
@@ -144,6 +146,7 @@
 #![allow(unused_variables)]
 #![feature(deref_patterns)]
 
+#[repr(C)]
 struct Struct {
     x: i16,
     y: f32,
diff --git a/tests/debuginfo/evec-in-struct.rs b/tests/debuginfo/evec-in-struct.rs
index 44e7d359d81ec..646091d5f3c1a 100644
--- a/tests/debuginfo/evec-in-struct.rs
+++ b/tests/debuginfo/evec-in-struct.rs
@@ -41,17 +41,20 @@
 
 #![allow(unused_variables)]
 
+#[repr(C)]
 struct NoPadding1 {
     x: [u32; 3],
     y: i32,
     z: [f32; 2]
 }
 
+#[repr(C)]
 struct NoPadding2 {
     x: [u32; 3],
     y: [[u32; 2]; 2]
 }
 
+#[repr(C)]
 struct StructInternalPadding {
     x: [i16; 2],
     y: [i64; 2]
@@ -61,6 +64,7 @@ struct SingleVec {
     x: [i16; 5]
 }
 
+#[repr(C)]
 struct StructPaddedAtEnd {
     x: [i64; 2],
     y: [i16; 2]
diff --git a/tests/debuginfo/packed-struct-with-destructor.rs b/tests/debuginfo/packed-struct-with-destructor.rs
index 59fc3d3ca15c2..9cb4c4ada03da 100644
--- a/tests/debuginfo/packed-struct-with-destructor.rs
+++ b/tests/debuginfo/packed-struct-with-destructor.rs
@@ -63,7 +63,7 @@
 
 #![allow(unused_variables)]
 
-#[repr(packed)]
+#[repr(C, packed)]
 struct Packed {
     x: i16,
     y: i32,
@@ -74,7 +74,7 @@ impl Drop for Packed {
     fn drop(&mut self) {}
 }
 
-#[repr(packed)]
+#[repr(C, packed)]
 struct PackedInPacked {
     a: i32,
     b: Packed,
@@ -82,6 +82,7 @@ struct PackedInPacked {
     d: Packed
 }
 
+#[repr(C)]
 struct PackedInUnpacked {
     a: i32,
     b: Packed,
@@ -89,6 +90,7 @@ struct PackedInUnpacked {
     d: Packed
 }
 
+#[repr(C)]
 struct Unpacked {
     x: i64,
     y: i32,
@@ -99,7 +101,7 @@ impl Drop for Unpacked {
     fn drop(&mut self) {}
 }
 
-#[repr(packed)]
+#[repr(C, packed)]
 struct UnpackedInPacked {
     a: i16,
     b: Unpacked,
@@ -107,7 +109,7 @@ struct UnpackedInPacked {
     d: i64
 }
 
-#[repr(packed)]
+#[repr(C, packed)]
 struct PackedInPackedWithDrop {
     a: i32,
     b: Packed,
@@ -119,6 +121,7 @@ impl Drop for PackedInPackedWithDrop {
     fn drop(&mut self) {}
 }
 
+#[repr(C)]
 struct PackedInUnpackedWithDrop {
     a: i32,
     b: Packed,
@@ -130,7 +133,7 @@ impl Drop for PackedInUnpackedWithDrop {
     fn drop(&mut self) {}
 }
 
-#[repr(packed)]
+#[repr(C, packed)]
 struct UnpackedInPackedWithDrop {
     a: i16,
     b: Unpacked,
@@ -142,6 +145,7 @@ impl Drop for UnpackedInPackedWithDrop {
     fn drop(&mut self) {}
 }
 
+#[repr(C)]
 struct DeeplyNested {
     a: PackedInPacked,
     b: UnpackedInPackedWithDrop,
diff --git a/tests/debuginfo/packed-struct.rs b/tests/debuginfo/packed-struct.rs
index e601ac1ffc6a2..f2e08fac063f6 100644
--- a/tests/debuginfo/packed-struct.rs
+++ b/tests/debuginfo/packed-struct.rs
@@ -49,14 +49,14 @@
 
 #![allow(unused_variables)]
 
-#[repr(packed)]
+#[repr(C, packed)]
 struct Packed {
     x: i16,
     y: i32,
     z: i64
 }
 
-#[repr(packed)]
+#[repr(C, packed)]
 struct PackedInPacked {
     a: i32,
     b: Packed,
@@ -64,6 +64,7 @@ struct PackedInPacked {
     d: Packed
 }
 
+#[repr(C)]
 // layout (64 bit): aaaa bbbb bbbb bbbb bb.. .... cccc cccc dddd dddd dddd dd..
 struct PackedInUnpacked {
     a: i32,
@@ -72,6 +73,7 @@ struct PackedInUnpacked {
     d: Packed
 }
 
+#[repr(C)]
 // layout (64 bit): xx.. yyyy zz.. .... wwww wwww
 struct Unpacked {
     x: i16,
@@ -81,7 +83,7 @@ struct Unpacked {
 }
 
 // layout (64 bit): aabb bbbb bbbb bbbb bbbb bbbb bbcc cccc cccc cccc cccc cccc ccdd dddd dd
-#[repr(packed)]
+#[repr(C, packed)]
 struct UnpackedInPacked {
     a: i16,
     b: Unpacked,
diff --git a/tests/debuginfo/simple-struct.rs b/tests/debuginfo/simple-struct.rs
index fe42e9d1421f1..5b3941452685c 100644
--- a/tests/debuginfo/simple-struct.rs
+++ b/tests/debuginfo/simple-struct.rs
@@ -87,23 +87,27 @@
 #![allow(unused_variables)]
 #![allow(dead_code)]
 
+#[repr(C)]
 struct NoPadding16 {
     x: u16,
     y: i16
 }
 
+#[repr(C)]
 struct NoPadding32 {
     x: i32,
     y: f32,
     z: u32
 }
 
+#[repr(C)]
 struct NoPadding64 {
     x: f64,
     y: i64,
     z: u64
 }
 
+#[repr(C)]
 struct NoPadding163264 {
     a: i16,
     b: u16,
@@ -111,11 +115,13 @@ struct NoPadding163264 {
     d: u64
 }
 
+#[repr(C)]
 struct InternalPadding {
     x: u16,
     y: i64
 }
 
+#[repr(C)]
 struct PaddingAtEnd {
     x: i64,
     y: u16
diff --git a/tests/debuginfo/struct-in-struct.rs b/tests/debuginfo/struct-in-struct.rs
index 8b7ceb0c7aa29..f4357292b6c67 100644
--- a/tests/debuginfo/struct-in-struct.rs
+++ b/tests/debuginfo/struct-in-struct.rs
@@ -50,34 +50,40 @@ struct Simple {
     x: i32
 }
 
+#[repr(C)]
 struct InternalPadding {
     x: i32,
     y: i64
 }
 
+#[repr(C)]
 struct PaddingAtEnd {
     x: i64,
     y: i32
 }
 
+#[repr(C)]
 struct ThreeSimpleStructs {
     x: Simple,
     y: Simple,
     z: Simple
 }
 
+#[repr(C)]
 struct InternalPaddingParent {
     x: InternalPadding,
     y: InternalPadding,
     z: InternalPadding
 }
 
+#[repr(C)]
 struct PaddingAtEndParent {
     x: PaddingAtEnd,
     y: PaddingAtEnd,
     z: PaddingAtEnd
 }
 
+#[repr(C)]
 struct Mixed {
     x: PaddingAtEnd,
     y: InternalPadding,
@@ -97,6 +103,7 @@ struct ThatsJustOverkill {
     x: BagInBag
 }
 
+#[repr(C)]
 struct Tree {
     x: Simple,
     y: InternalPaddingParent,
diff --git a/tests/debuginfo/struct-with-destructor.rs b/tests/debuginfo/struct-with-destructor.rs
index a0ada74bc2f8f..0872d3501de26 100644
--- a/tests/debuginfo/struct-with-destructor.rs
+++ b/tests/debuginfo/struct-with-destructor.rs
@@ -35,11 +35,13 @@
 
 #![allow(unused_variables)]
 
+#[repr(C)]
 struct NoDestructor {
     x: i32,
     y: i64
 }
 
+#[repr(C)]
 struct WithDestructor {
     x: i32,
     y: i64
@@ -49,11 +51,13 @@ impl Drop for WithDestructor {
     fn drop(&mut self) {}
 }
 
+#[repr(C)]
 struct NoDestructorGuarded {
     a: NoDestructor,
     guard: i64
 }
 
+#[repr(C)]
 struct WithDestructorGuarded {
     a: WithDestructor,
     guard: i64
diff --git a/tests/debuginfo/vec-slices.rs b/tests/debuginfo/vec-slices.rs
index b5e626854ae3c..1657e55c1cfdc 100644
--- a/tests/debuginfo/vec-slices.rs
+++ b/tests/debuginfo/vec-slices.rs
@@ -74,6 +74,7 @@
 
 #![allow(dead_code, unused_variables)]
 
+#[repr(C)]
 struct AStruct {
     x: i16,
     y: i32,