fix(attr-fallthrough): ensure consistent attr fallthrough for root fragments with comments

fix #2549

packages/shared/src/patchFlags.ts

@@ -1,89 +1,127 @@
-// Patch flags are optimization hints generated by the compiler.
-// when a block with dynamicChildren is encountered during diff, the algorithm
-// enters "optimized mode". In this mode, we know that the vdom is produced by
-// a render function generated by the compiler, so the algorithm only needs to
-// handle updates explicitly marked by these patch flags.
-
-// Patch flags can be combined using the | bitwise operator and can be checked
-// using the & operator, e.g.
-//
-//   const flag = TEXT | CLASS
-//   if (flag & TEXT) { ... }
-//
-// Check the `patchElement` function in './renderer.ts' to see how the
-// flags are handled during diff.
-
+/**
+ * Patch flags are optimization hints generated by the compiler.
+ * when a block with dynamicChildren is encountered during diff, the algorithm
+ * enters "optimized mode". In this mode, we know that the vdom is produced by
+ * a render function generated by the compiler, so the algorithm only needs to
+ * handle updates explicitly marked by these patch flags.
+ *
+ * Patch flags can be combined using the | bitwise operator and can be checked
+ * using the & operator, e.g.
+ *
+ * ```js
+ * const flag = TEXT | CLASS
+ * if (flag & TEXT) { ... }
+ * ```
+ *
+ * Check the `patchElement` function in './renderer.ts' to see how the
+ * flags are handled during diff.
+ */
 export const enum PatchFlags {
-  // Indicates an element with dynamic textContent (children fast path)
+  /**
+   * Indicates an element with dynamic textContent (children fast path)
+   */
   TEXT = 1,
 
-  // Indicates an element with dynamic class binding.
+  /**
+   * Indicates an element with dynamic class binding.
+   */
   CLASS = 1 << 1,
 
-  // Indicates an element with dynamic style
-  // The compiler pre-compiles static string styles into static objects
-  // + detects and hoists inline static objects
-  // e.g. style="color: red" and :style="{ color: 'red' }" both get hoisted as
-  //   const style = { color: 'red' }
-  //   render() { return e('div', { style }) }
+  /**
+   * Indicates an element with dynamic style
+   * The compiler pre-compiles static string styles into static objects
+   * + detects and hoists inline static objects
+   * e.g. style="color: red" and :style="{ color: 'red' }" both get hoisted as
+   *   const style = { color: 'red' }
+   *   render() { return e('div', { style }) }
+   */
   STYLE = 1 << 2,
 
-  // Indicates an element that has non-class/style dynamic props.
-  // Can also be on a component that has any dynamic props (includes
-  // class/style). when this flag is present, the vnode also has a dynamicProps
-  // array that contains the keys of the props that may change so the runtime
-  // can diff them faster (without having to worry about removed props)
+  /**
+   * Indicates an element that has non-class/style dynamic props.
+   * Can also be on a component that has any dynamic props (includes
+   * class/style). when this flag is present, the vnode also has a dynamicProps
+   * array that contains the keys of the props that may change so the runtime
+   * can diff them faster (without having to worry about removed props)
+   */
   PROPS = 1 << 3,
 
-  // Indicates an element with props with dynamic keys. When keys change, a full
-  // diff is always needed to remove the old key. This flag is mutually
-  // exclusive with CLASS, STYLE and PROPS.
+  /**
+   * Indicates an element with props with dynamic keys. When keys change, a full
+   * diff is always needed to remove the old key. This flag is mutually
+   * exclusive with CLASS, STYLE and PROPS.
+   */
   FULL_PROPS = 1 << 4,
 
-  // Indicates an element with event listeners (which need to be attached
-  // during hydration)
+  /**
+   * Indicates an element with event listeners (which need to be attached
+   * during hydration)
+   */
   HYDRATE_EVENTS = 1 << 5,
 
-  // Indicates a fragment whose children order doesn't change.
+  /**
+   * Indicates a fragment whose children order doesn't change.
+   */
   STABLE_FRAGMENT = 1 << 6,
 
-  // Indicates a fragment with keyed or partially keyed children
+  /**
+   * Indicates a fragment with keyed or partially keyed children
+   */
   KEYED_FRAGMENT = 1 << 7,
 
-  // Indicates a fragment with unkeyed children.
+  /**
+   * Indicates a fragment with unkeyed children.
+   */
   UNKEYED_FRAGMENT = 1 << 8,
 
-  // Indicates an element that only needs non-props patching, e.g. ref or
-  // directives (onVnodeXXX hooks). since every patched vnode checks for refs
-  // and onVnodeXXX hooks, it simply marks the vnode so that a parent block
-  // will track it.
+  /**
+   * Indicates an element that only needs non-props patching, e.g. ref or
+   * directives (onVnodeXXX hooks). since every patched vnode checks for refs
+   * and onVnodeXXX hooks, it simply marks the vnode so that a parent block
+   * will track it.
+   */
   NEED_PATCH = 1 << 9,
 
-  // Indicates a component with dynamic slots (e.g. slot that references a v-for
-  // iterated value, or dynamic slot names).
-  // Components with this flag are always force updated.
+  /**
+   * Indicates a component with dynamic slots (e.g. slot that references a v-for
+   * iterated value, or dynamic slot names).
+   * Components with this flag are always force updated.
+   */
   DYNAMIC_SLOTS = 1 << 10,
 
-  // SPECIAL FLAGS -------------------------------------------------------------
+  /**
+   * Indicates a fragment that was created only because the user has placed
+   * comments at the root level of a template. This is a dev-only flag since
+   * comments are stripped in production.
+   */
+  DEV_ROOT_FRAGMENT = 1 << 11,
 
-  // Special flags are negative integers. They are never matched against using
-  // bitwise operators (bitwise matching should only happen in branches where
-  // patchFlag > 0), and are mutually exclusive. When checking for a special
-  // flag, simply check patchFlag === FLAG.
+  /**
+   * SPECIAL FLAGS -------------------------------------------------------------
+   * Special flags are negative integers. They are never matched against using
+   * bitwise operators (bitwise matching should only happen in branches where
+   * patchFlag > 0), and are mutually exclusive. When checking for a special
+   * flag, simply check patchFlag === FLAG.
+   */
 
-  // Indicates a hoisted static vnode. This is a hint for hydration to skip
-  // the entire sub tree since static content never needs to be updated.
+  /**
+   * Indicates a hoisted static vnode. This is a hint for hydration to skip
+   * the entire sub tree since static content never needs to be updated.
+   */
   HOISTED = -1,
-
-  // A special flag that indicates that the diffing algorithm should bail out
-  // of optimized mode. For example, on block fragments created by renderSlot()
-  // when encountering non-compiler generated slots (i.e. manually written
-  // render functions, which should always be fully diffed)
-  // OR manually cloneVNodes
+  /**
+   * A special flag that indicates that the diffing algorithm should bail out
+   * of optimized mode. For example, on block fragments created by renderSlot()
+   * when encountering non-compiler generated slots (i.e. manually written
+   * render functions, which should always be fully diffed)
+   * OR manually cloneVNodes
+   */
   BAIL = -2
 }
 
-// dev only flag -> name mapping
+/**
+ * dev only flag -> name mapping
+ */
 export const PatchFlagNames = {
   [PatchFlags.TEXT]: `TEXT`,
   [PatchFlags.CLASS]: `CLASS`,
@@ -94,8 +132,9 @@ export const PatchFlagNames = {
   [PatchFlags.STABLE_FRAGMENT]: `STABLE_FRAGMENT`,
   [PatchFlags.KEYED_FRAGMENT]: `KEYED_FRAGMENT`,
   [PatchFlags.UNKEYED_FRAGMENT]: `UNKEYED_FRAGMENT`,
-  [PatchFlags.DYNAMIC_SLOTS]: `DYNAMIC_SLOTS`,
   [PatchFlags.NEED_PATCH]: `NEED_PATCH`,
+  [PatchFlags.DYNAMIC_SLOTS]: `DYNAMIC_SLOTS`,
+  [PatchFlags.DEV_ROOT_FRAGMENT]: `DEV_ROOT_FRAGMENT`,
   [PatchFlags.HOISTED]: `HOISTED`,
   [PatchFlags.BAIL]: `BAIL`
 }