tor-browser

commit 2da44da5de3ba36feece11f887ee6180a38f1cbe
parent 97881a44751d12ebf8e6fbfdf5dbeb9c70428069
Author: Frédéric Wang <fwang@igalia.com>
Date:   Tue,  6 Jan 2026 05:35:36 +0000

Bug 2008530 - Part 2 - Use `nsGlyphTable::IsUnicodeTable()` instead of raw pointer comparison. r=layout-reviewers,dshin,sergesanspaille

`glyph table == &gUnicodeTable` is used in three places with the glyph
table nullptr in `nsMathMLChar::SetFontFamily` when called from
https://searchfox.org/firefox-main/rev/e61d59b5c9a651fd7bf28043f87c0dc669833496/layout/mathml/nsMathMLChar.cpp#1279

Differential Revision: https://phabricator.services.mozilla.com/D277860

Diffstat:
M
layout/mathml/nsMathMLChar.cpp
 | 
10
+++++++---

1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/layout/mathml/nsMathMLChar.cpp b/layout/mathml/nsMathMLChar.cpp
@@ -73,6 +73,7 @@ static const nsGlyphCode kNullGlyph = {{0}, false};
 class nsGlyphTable {
  public:
   virtual ~nsGlyphTable() = default;
+  virtual bool IsUnicodeTable() const { return false; }
 
   virtual const nsCString& FontNameFor(const nsGlyphCode& aGlyphCode) const = 0;
 
@@ -169,6 +170,8 @@ class nsUnicodeTable final : public nsGlyphTable {
  public:
   constexpr nsUnicodeTable() = default;
 
+  bool IsUnicodeTable() const final { return true; };
+
   const nsCString& FontNameFor(const nsGlyphCode& aGlyphCode) const override {
     MOZ_ASSERT_UNREACHABLE();
     return VoidCString();
@@ -663,7 +666,7 @@ bool nsMathMLChar::SetFontFamily(nsPresContext* aPresContext,
     // Set the font if it is an unicode table or if the same family name has
     // been found.
     const bool shouldSetFont = [&] {
-      if (aGlyphTable == &gUnicodeTable) {
+      if (aGlyphTable && aGlyphTable->IsUnicodeTable()) {
         return true;
       }
 
@@ -939,7 +942,7 @@ bool nsMathMLChar::StretchEnumContext::TryParts(
 
   // For the Unicode table, we check that all the glyphs are actually found and
   // come from the same font.
-  if (aGlyphTable == &gUnicodeTable) {
+  if (aGlyphTable->IsUnicodeTable()) {
     gfxFont* unicodeFont = nullptr;
     for (int32_t i = 0; i < 4; i++) {
       if (!textRun[i]) {
@@ -1107,6 +1110,7 @@ bool nsMathMLChar::StretchEnumContext::EnumCallback(
     // Fallback to the Unicode table.
     return &gUnicodeTable;
   }();
+  MOZ_ASSERT(glyphTable);
 
   if (!openTypeTable) {
     // Make sure we only try the UnicodeTable once.
@@ -1120,7 +1124,7 @@ bool nsMathMLChar::StretchEnumContext::EnumCallback(
   // special table is being used then the font in this family should have the
   // specified glyphs.
   const StyleFontFamilyList& familyList =
-      glyphTable == &gUnicodeTable ? context->mFamilyList : family;
+      glyphTable->IsUnicodeTable() ? context->mFamilyList : family;
 
   return (context->mTryVariants &&
           context->TryVariants(glyphTable, &fontGroup, familyList, aRtl)) ||