constant: Allow more constexpr constants.

mozilla · Apr 21, 2022 · 15e1131 · 15e1131
1 parent a0ab624
commit 15e1131
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Showing 7 changed files with 76 additions and 33 deletions.
diff --git a/src/bindgen/ir/constant.rs b/src/bindgen/ir/constant.rs
@@ -183,22 +183,60 @@ impl Literal {
         }
     }
 
-    pub fn uses_only_primitive_types(&self) -> bool {
+    fn can_be_constexpr(&self) -> bool {
+        !self.has_pointer_casts()
+    }
+
+    fn visit(&self, visitor: &mut impl FnMut(&Self) -> bool) -> bool {
+        if !visitor(self) {
+            return false;
+        }
         match self {
             Literal::Expr(..) | Literal::Path { .. } => true,
-            Literal::PostfixUnaryOp { ref value, .. } => value.uses_only_primitive_types(),
+            Literal::PostfixUnaryOp { ref value, .. } => value.visit(visitor),
             Literal::BinOp {
                 ref left,
                 ref right,
                 ..
-            } => left.uses_only_primitive_types() & right.uses_only_primitive_types(),
-            Literal::FieldAccess { ref base, .. } => base.uses_only_primitive_types(),
-            Literal::Struct { .. } => false,
-            Literal::Cast { ref value, ref ty } => {
-                value.uses_only_primitive_types() && ty.is_primitive_or_ptr_primitive()
+            } => left.visit(visitor) && right.visit(visitor),
+            Literal::FieldAccess { ref base, .. } => base.visit(visitor),
+            Literal::Struct { ref fields, .. } => {
+                for (_name, field) in fields.iter() {
+                    if !field.visit(visitor) {
+                        return false;
+                    }
+                }
+                true
             }
+            Literal::Cast { ref value, .. } => value.visit(visitor),
         }
     }
+
+    fn has_pointer_casts(&self) -> bool {
+        let mut has_pointer_casts = false;
+        self.visit(&mut |lit| {
+            if let Literal::Cast { ref ty, .. } = *lit {
+                has_pointer_casts = has_pointer_casts || ty.is_ptr();
+            }
+            !has_pointer_casts
+        });
+        has_pointer_casts
+    }
+
+    pub fn uses_only_primitive_types(&self) -> bool {
+        let mut uses_only_primitive_types = true;
+        self.visit(&mut |lit| {
+            // XXX This is a bit sketchy, but alas.
+            uses_only_primitive_types = uses_only_primitive_types
+                && match *lit {
+                    Literal::Struct { .. } => false,
+                    Literal::Cast { ref ty, .. } => ty.is_primitive_or_ptr_primitive(),
+                    _ => true,
+                };
+            uses_only_primitive_types
+        });
+        uses_only_primitive_types
+    }
 }
 
 impl Literal {
@@ -720,12 +758,7 @@ impl Constant {
 
         self.documentation.write(config, out);
 
-        let allow_constexpr = if let Type::Primitive(..) = self.ty {
-            config.constant.allow_constexpr
-        } else {
-            false
-        };
-
+        let allow_constexpr = config.constant.allow_constexpr && self.value.can_be_constexpr();
         match config.language {
             Language::Cxx if config.constant.allow_static_const || allow_constexpr => {
                 if allow_constexpr {

diff --git a/src/bindgen/ir/ty.rs b/src/bindgen/ir/ty.rs
@@ -501,6 +501,10 @@ impl Type {
         Ok(Some(converted))
     }
 
+    pub fn is_ptr(&self) -> bool {
+        matches!(*self, Type::Ptr { .. } | Type::FuncPtr { .. })
+    }
+
     pub fn is_primitive_or_ptr_primitive(&self) -> bool {
         match *self {
             Type::Primitive(..) => true,

diff --git a/tests/expectations/associated_in_body.cpp b/tests/expectations/associated_in_body.cpp
@@ -47,26 +47,26 @@ struct StyleAlignFlags {
   static const StyleAlignFlags MIXED_SELF;
 };
 /// 'auto'
-inline const StyleAlignFlags StyleAlignFlags::AUTO = StyleAlignFlags{ /* .bits = */ (uint8_t)0 };
+constexpr inline const StyleAlignFlags StyleAlignFlags::AUTO = StyleAlignFlags{ /* .bits = */ (uint8_t)0 };
 /// 'normal'
-inline const StyleAlignFlags StyleAlignFlags::NORMAL = StyleAlignFlags{ /* .bits = */ (uint8_t)1 };
+constexpr inline const StyleAlignFlags StyleAlignFlags::NORMAL = StyleAlignFlags{ /* .bits = */ (uint8_t)1 };
 /// 'start'
-inline const StyleAlignFlags StyleAlignFlags::START = StyleAlignFlags{ /* .bits = */ (uint8_t)(1 << 1) };
+constexpr inline const StyleAlignFlags StyleAlignFlags::START = StyleAlignFlags{ /* .bits = */ (uint8_t)(1 << 1) };
 /// 'end'
-inline const StyleAlignFlags StyleAlignFlags::END = StyleAlignFlags{ /* .bits = */ (uint8_t)(1 << 2) };
-inline const StyleAlignFlags StyleAlignFlags::ALIAS = StyleAlignFlags{ /* .bits = */ (uint8_t)(StyleAlignFlags::END).bits };
+constexpr inline const StyleAlignFlags StyleAlignFlags::END = StyleAlignFlags{ /* .bits = */ (uint8_t)(1 << 2) };
+constexpr inline const StyleAlignFlags StyleAlignFlags::ALIAS = StyleAlignFlags{ /* .bits = */ (uint8_t)(StyleAlignFlags::END).bits };
 /// 'flex-start'
-inline const StyleAlignFlags StyleAlignFlags::FLEX_START = StyleAlignFlags{ /* .bits = */ (uint8_t)(1 << 3) };
-inline const StyleAlignFlags StyleAlignFlags::MIXED = StyleAlignFlags{ /* .bits = */ (uint8_t)(((1 << 4) | (StyleAlignFlags::FLEX_START).bits) | (StyleAlignFlags::END).bits) };
-inline const StyleAlignFlags StyleAlignFlags::MIXED_SELF = StyleAlignFlags{ /* .bits = */ (uint8_t)(((1 << 5) | (StyleAlignFlags::FLEX_START).bits) | (StyleAlignFlags::END).bits) };
+constexpr inline const StyleAlignFlags StyleAlignFlags::FLEX_START = StyleAlignFlags{ /* .bits = */ (uint8_t)(1 << 3) };
+constexpr inline const StyleAlignFlags StyleAlignFlags::MIXED = StyleAlignFlags{ /* .bits = */ (uint8_t)(((1 << 4) | (StyleAlignFlags::FLEX_START).bits) | (StyleAlignFlags::END).bits) };
+constexpr inline const StyleAlignFlags StyleAlignFlags::MIXED_SELF = StyleAlignFlags{ /* .bits = */ (uint8_t)(((1 << 5) | (StyleAlignFlags::FLEX_START).bits) | (StyleAlignFlags::END).bits) };
 
 /// An arbitrary identifier for a native (OS compositor) surface
 struct StyleNativeSurfaceId {
   uint64_t _0;
   static const StyleNativeSurfaceId DEBUG_OVERLAY;
 };
 /// A special id for the native surface that is used for debug / profiler overlays.
-inline const StyleNativeSurfaceId StyleNativeSurfaceId::DEBUG_OVERLAY = StyleNativeSurfaceId{ /* ._0 = */ UINT64_MAX };
+constexpr inline const StyleNativeSurfaceId StyleNativeSurfaceId::DEBUG_OVERLAY = StyleNativeSurfaceId{ /* ._0 = */ UINT64_MAX };
 
 struct StyleNativeTileId {
   StyleNativeSurfaceId surface_id;
@@ -75,7 +75,7 @@ struct StyleNativeTileId {
   static const StyleNativeTileId DEBUG_OVERLAY;
 };
 /// A special id for the native surface that is used for debug / profiler overlays.
-inline const StyleNativeTileId StyleNativeTileId::DEBUG_OVERLAY = StyleNativeTileId{ /* .surface_id = */ StyleNativeSurfaceId::DEBUG_OVERLAY, /* .x = */ 0, /* .y = */ 0 };
+constexpr inline const StyleNativeTileId StyleNativeTileId::DEBUG_OVERLAY = StyleNativeTileId{ /* .surface_id = */ StyleNativeSurfaceId::DEBUG_OVERLAY, /* .x = */ 0, /* .y = */ 0 };
 
 extern "C" {
 

diff --git a/tests/expectations/bitflags.cpp b/tests/expectations/bitflags.cpp
@@ -39,18 +39,18 @@ struct AlignFlags {
   }
 };
 /// 'auto'
-static const AlignFlags AlignFlags_AUTO = AlignFlags{ /* .bits = */ (uint8_t)0 };
+constexpr static const AlignFlags AlignFlags_AUTO = AlignFlags{ /* .bits = */ (uint8_t)0 };
 /// 'normal'
-static const AlignFlags AlignFlags_NORMAL = AlignFlags{ /* .bits = */ (uint8_t)1 };
+constexpr static const AlignFlags AlignFlags_NORMAL = AlignFlags{ /* .bits = */ (uint8_t)1 };
 /// 'start'
-static const AlignFlags AlignFlags_START = AlignFlags{ /* .bits = */ (uint8_t)(1 << 1) };
+constexpr static const AlignFlags AlignFlags_START = AlignFlags{ /* .bits = */ (uint8_t)(1 << 1) };
 /// 'end'
-static const AlignFlags AlignFlags_END = AlignFlags{ /* .bits = */ (uint8_t)(1 << 2) };
-static const AlignFlags AlignFlags_ALIAS = AlignFlags{ /* .bits = */ (uint8_t)(AlignFlags_END).bits };
+constexpr static const AlignFlags AlignFlags_END = AlignFlags{ /* .bits = */ (uint8_t)(1 << 2) };
+constexpr static const AlignFlags AlignFlags_ALIAS = AlignFlags{ /* .bits = */ (uint8_t)(AlignFlags_END).bits };
 /// 'flex-start'
-static const AlignFlags AlignFlags_FLEX_START = AlignFlags{ /* .bits = */ (uint8_t)(1 << 3) };
-static const AlignFlags AlignFlags_MIXED = AlignFlags{ /* .bits = */ (uint8_t)(((1 << 4) | (AlignFlags_FLEX_START).bits) | (AlignFlags_END).bits) };
-static const AlignFlags AlignFlags_MIXED_SELF = AlignFlags{ /* .bits = */ (uint8_t)(((1 << 5) | (AlignFlags_FLEX_START).bits) | (AlignFlags_END).bits) };
+constexpr static const AlignFlags AlignFlags_FLEX_START = AlignFlags{ /* .bits = */ (uint8_t)(1 << 3) };
+constexpr static const AlignFlags AlignFlags_MIXED = AlignFlags{ /* .bits = */ (uint8_t)(((1 << 4) | (AlignFlags_FLEX_START).bits) | (AlignFlags_END).bits) };
+constexpr static const AlignFlags AlignFlags_MIXED_SELF = AlignFlags{ /* .bits = */ (uint8_t)(((1 << 5) | (AlignFlags_FLEX_START).bits) | (AlignFlags_END).bits) };
 
 struct DebugFlags {
   uint32_t bits;
@@ -84,7 +84,7 @@ struct DebugFlags {
   }
 };
 /// Flag with the topmost bit set of the u32
-static const DebugFlags DebugFlags_BIGGEST_ALLOWED = DebugFlags{ /* .bits = */ (uint32_t)(1 << 31) };
+constexpr static const DebugFlags DebugFlags_BIGGEST_ALLOWED = DebugFlags{ /* .bits = */ (uint32_t)(1 << 31) };
 
 extern "C" {
 

diff --git a/tests/expectations/constant_constexpr.cpp b/tests/expectations/constant_constexpr.cpp
@@ -18,4 +18,4 @@ struct Foo {
 };
 constexpr inline const int64_t Foo::CONSTANT_I64_BODY = 216;
 
-static const Foo SomeFoo = Foo{ /* .x = */ 99 };
+constexpr static const Foo SomeFoo = Foo{ /* .x = */ 99 };
diff --git a/tests/rust/associated_in_body.toml b/tests/rust/associated_in_body.toml
@@ -6,3 +6,6 @@ bitflags = true
 
 [export]
 prefix = "Style" # Just ensuring they play well together :)
+
+[const]
+allow_constexpr = true
diff --git a/tests/rust/bitflags.toml b/tests/rust/bitflags.toml
@@ -1,2 +1,5 @@
 [macro_expansion]
 bitflags = true
+
+[const]
+allow_constexpr = true