Breaking: Fix callback const-correctness (#1369)

Summary:
Pull Request resolved: https://github.com/facebook/yoga/pull/1369

X-link: https://github.com/facebook/react-native/pull/39370

This fixes const-correctness of callbacks (e.g. not letting a logger function modify nodes during layout). This helps us to continue to fix const-correctness issues inside of Yoga.

This change is breaking to the public API, since it requires a change in signature passed to Yoga.

Changelog: [Internal]

Reviewed By: rshest

Differential Revision: D49130714

fbshipit-source-id: 4305f8882d89f296e45b78497a51716a0dbb3b2d

yoga/Yoga.cpp

@@ -22,15 +22,15 @@ using namespace facebook::yoga;
 
 #ifdef ANDROID
 static int YGAndroidLog(
-    const YGConfigRef config,
-    const YGNodeRef node,
+    const YGConfigConstRef config,
+    const YGNodeConstRef node,
     YGLogLevel level,
     const char* format,
     va_list args);
 #else
 static int YGDefaultLog(
-    const YGConfigRef config,
-    const YGNodeRef node,
+    const YGConfigConstRef config,
+    const YGNodeConstRef node,
     YGLogLevel level,
     const char* format,
     va_list args);
@@ -39,8 +39,8 @@ static int YGDefaultLog(
 #ifdef ANDROID
 #include <android/log.h>
 static int YGAndroidLog(
-    const YGConfigRef /*config*/,
-    const YGNodeRef /*node*/,
+    const YGConfigConstRef /*config*/,
+    const YGNodeConstRef /*node*/,
     YGLogLevel level,
     const char* format,
     va_list args) {
@@ -69,16 +69,12 @@ static int YGAndroidLog(
   return result;
 }
 #else
-#define YG_UNUSED(x) (void) (x);
-
 static int YGDefaultLog(
-    const YGConfigRef config,
-    const YGNodeRef node,
+    const YGConfigConstRef /*config*/,
+    const YGNodeConstRef /*node*/,
     YGLogLevel level,
     const char* format,
     va_list args) {
-  YG_UNUSED(config);
-  YG_UNUSED(node);
   switch (level) {
     case YGLogLevelError:
     case YGLogLevelFatal:
@@ -91,8 +87,6 @@ static int YGDefaultLog(
       return vprintf(format, args);
   }
 }
-
-#undef YG_UNUSED
 #endif
 
 YOGA_EXPORT bool YGFloatIsUndefined(const float value) {
@@ -202,7 +196,7 @@ YOGA_EXPORT YGNodeRef YGNodeNew(void) {
   return YGNodeNewWithConfig(YGConfigGetDefault());
 }
 
-YOGA_EXPORT YGNodeRef YGNodeClone(YGNodeRef oldNodeRef) {
+YOGA_EXPORT YGNodeRef YGNodeClone(YGNodeConstRef oldNodeRef) {
   auto oldNode = resolveRef(oldNodeRef);
   const auto node = new yoga::Node(*oldNode);
   yoga::assertFatalWithConfig(

yoga/Yoga.h

@@ -29,28 +29,30 @@ typedef struct YGNode* YGNodeRef;
 typedef const struct YGNode* YGNodeConstRef;
 
 typedef YGSize (*YGMeasureFunc)(
-    YGNodeRef node,
+    YGNodeConstRef node,
     float width,
     YGMeasureMode widthMode,
     float height,
     YGMeasureMode heightMode);
-typedef float (*YGBaselineFunc)(YGNodeRef node, float width, float height);
-typedef void (*YGDirtiedFunc)(YGNodeRef node);
-typedef void (*YGPrintFunc)(YGNodeRef node);
-typedef void (*YGNodeCleanupFunc)(YGNodeRef node);
+typedef float (*YGBaselineFunc)(YGNodeConstRef node, float width, float height);
+typedef void (*YGDirtiedFunc)(YGNodeConstRef node);
+typedef void (*YGPrintFunc)(YGNodeConstRef node);
+typedef void (*YGNodeCleanupFunc)(YGNodeConstRef node);
 typedef int (*YGLogger)(
-    YGConfigRef config,
-    YGNodeRef node,
+    YGConfigConstRef config,
+    YGNodeConstRef node,
     YGLogLevel level,
     const char* format,
     va_list args);
-typedef YGNodeRef (
-    *YGCloneNodeFunc)(YGNodeRef oldNode, YGNodeRef owner, int childIndex);
+typedef YGNodeRef (*YGCloneNodeFunc)(
+    YGNodeConstRef oldNode,
+    YGNodeConstRef owner,
+    int childIndex);
 
 // YGNode
 WIN_EXPORT YGNodeRef YGNodeNew(void);
 WIN_EXPORT YGNodeRef YGNodeNewWithConfig(YGConfigRef config);
-WIN_EXPORT YGNodeRef YGNodeClone(YGNodeRef node);
+WIN_EXPORT YGNodeRef YGNodeClone(YGNodeConstRef node);
 WIN_EXPORT void YGNodeFree(YGNodeRef node);
 WIN_EXPORT void YGNodeFreeRecursiveWithCleanupFunc(
     YGNodeRef node,

yoga/config/Config.cpp

@@ -107,23 +107,10 @@ void Config::log(
     void* logContext,
     const char* format,
     va_list args) const {
-  // TODO: Break log callback signatures to make them const correct
-
   if (flags_.loggerUsesContext) {
-    logger_.withContext(
-        const_cast<yoga::Config*>(this),
-        const_cast<yoga::Node*>(node),
-        logLevel,
-        logContext,
-        format,
-        args);
+    logger_.withContext(this, node, logLevel, logContext, format, args);
   } else {
-    logger_.noContext(
-        const_cast<yoga::Config*>(this),
-        const_cast<yoga::Node*>(node),
-        logLevel,
-        format,
-        args);
+    logger_.noContext(this, node, logLevel, format, args);
   }
 }
 
@@ -142,8 +129,8 @@ void Config::setCloneNodeCallback(std::nullptr_t) {
 }
 
 YGNodeRef Config::cloneNode(
-    YGNodeRef node,
-    YGNodeRef owner,
+    YGNodeConstRef node,
+    YGNodeConstRef owner,
     int childIndex,
     void* cloneContext) const {
   YGNodeRef clone = nullptr;

yoga/config/Config.h

@@ -25,15 +25,15 @@ bool configUpdateInvalidatesLayout(Config* a, Config* b);
 // Internal variants of log functions, currently used only by JNI bindings.
 // TODO: Reconcile this with the public API
 using LogWithContextFn = int (*)(
-    YGConfigRef config,
-    YGNodeRef node,
+    YGConfigConstRef config,
+    YGNodeConstRef node,
     YGLogLevel level,
     void* context,
     const char* format,
     va_list args);
 using CloneWithContextFn = YGNodeRef (*)(
-    YGNodeRef node,
-    YGNodeRef owner,
+    YGNodeConstRef node,
+    YGNodeConstRef owner,
     int childIndex,
     void* cloneContext);
 
@@ -90,8 +90,8 @@ public:
   void setCloneNodeCallback(CloneWithContextFn cloneNode);
   void setCloneNodeCallback(std::nullptr_t);
   YGNodeRef cloneNode(
-      YGNodeRef node,
-      YGNodeRef owner,
+      YGNodeConstRef node,
+      YGNodeConstRef owner,
       int childIndex,
       void* cloneContext) const;
 

yoga/node/Node.h

@@ -38,10 +38,17 @@ struct NodeFlags {
 
 class YOGA_EXPORT Node : public ::YGNode {
 public:
-  using MeasureWithContextFn =
-      YGSize (*)(YGNode*, float, YGMeasureMode, float, YGMeasureMode, void*);
-  using BaselineWithContextFn = float (*)(YGNode*, float, float, void*);
-  using PrintWithContextFn = void (*)(YGNode*, void*);
+  // Internal variants of callbacks, currently used only by JNI bindings.
+  // TODO: Reconcile this with the public API
+  using MeasureWithContextFn = YGSize (*)(
+      YGNodeConstRef,
+      float,
+      YGMeasureMode,
+      float,
+      YGMeasureMode,
+      void*);
+  using BaselineWithContextFn = float (*)(YGNodeConstRef, float, float, void*);
+  using PrintWithContextFn = void (*)(YGNodeConstRef, void*);
 
 private:
   void* context_ = nullptr;