Remove last traces of old Harfbuzz

In Qt 6, we removed the "old" Harfbuzz and Harfbuzz-NG became the
only option. But the QT_HARFBUZZ=old environment variable would
still be read and would disable certain parts of the code path.

This has caused some confusion when porting older applications,
where QT_HARFBUZZ=old was used to work around issues with the
earlier versions of Harfbuzz-NG. Setting it now causes text to
disappear completely.

To avoid this confusion, we remove traces of the QT_HARFBUZZ
environment variable as well.

[ChangeLog][Text] Fixed an issue where setting the legacy
environment variable QT_HARFBUZZ=old would cause text to
disappear from the application.

Fixes: QTBUG-102774
Change-Id: I0f07cdb2418202fc36b82e766ad9547c34477175
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>

2 files changed, 20 insertions, 38 deletions

diff --git a/src/gui/text/qfontengine.cpp b/src/gui/text/qfontengine.cpp
index 80c28a376a..1c78642b3a 100644
--- a/src/gui/text/qfontengine.cpp
+++ b/src/gui/text/qfontengine.cpp
@@ -90,17 +90,6 @@ static inline bool qSafeFromBigEndian(const uchar *source, const uchar *end, T *
     return true;
 }
 
-// Harfbuzz helper functions
-
-#if QT_CONFIG(harfbuzz)
-Q_GLOBAL_STATIC_WITH_ARGS(bool, useHarfbuzzNG,(qgetenv("QT_HARFBUZZ") != "old"))
-
-bool qt_useHarfbuzzNG()
-{
-    return *useHarfbuzzNG();
-}
-#endif
-
 int QFontEngine::getPointInOutline(glyph_t glyph, int flags, quint32 point, QFixed *xpos, QFixed *ypos, quint32 *nPoints)
 {
     Q_UNUSED(glyph);
@@ -199,20 +188,20 @@ void *QFontEngine::harfbuzzFont() const
 {
     Q_ASSERT(type() != QFontEngine::Multi);
 #if QT_CONFIG(harfbuzz)
-    if (qt_useHarfbuzzNG())
-        return hb_qt_font_get_for_engine(const_cast<QFontEngine *>(this));
-#endif
+    return hb_qt_font_get_for_engine(const_cast<QFontEngine *>(this));
+#else
     return nullptr;
+#endif
 }
 
 void *QFontEngine::harfbuzzFace() const
 {
     Q_ASSERT(type() != QFontEngine::Multi);
 #if QT_CONFIG(harfbuzz)
-    if (qt_useHarfbuzzNG())
-        return hb_qt_face_get_for_engine(const_cast<QFontEngine *>(this));
-#endif
+     return hb_qt_face_get_for_engine(const_cast<QFontEngine *>(this));
+#else
     return nullptr;
+#endif
 }
 
 bool QFontEngine::supportsScript(QChar::Script script) const
@@ -227,23 +216,21 @@ bool QFontEngine::supportsScript(QChar::Script script) const
         return true;
 
 #if QT_CONFIG(harfbuzz)
-    if (qt_useHarfbuzzNG()) {
-        // in AAT fonts, 'gsub' table is effectively replaced by 'mort'/'morx' table
-        uint lenMort = 0, lenMorx = 0;
-        if (getSfntTableData(MAKE_TAG('m','o','r','t'), nullptr, &lenMort) || getSfntTableData(MAKE_TAG('m','o','r','x'), nullptr, &lenMorx))
-            return true;
+    // in AAT fonts, 'gsub' table is effectively replaced by 'mort'/'morx' table
+    uint lenMort = 0, lenMorx = 0;
+    if (getSfntTableData(MAKE_TAG('m','o','r','t'), nullptr, &lenMort) || getSfntTableData(MAKE_TAG('m','o','r','x'), nullptr, &lenMorx))
+        return true;
 
-        if (hb_face_t *face = hb_qt_face_get_for_engine(const_cast<QFontEngine *>(this))) {
-            unsigned int script_count = HB_OT_MAX_TAGS_PER_SCRIPT;
-            hb_tag_t script_tags[HB_OT_MAX_TAGS_PER_SCRIPT];
+    if (hb_face_t *face = hb_qt_face_get_for_engine(const_cast<QFontEngine *>(this))) {
+        unsigned int script_count = HB_OT_MAX_TAGS_PER_SCRIPT;
+        hb_tag_t script_tags[HB_OT_MAX_TAGS_PER_SCRIPT];
 
-            hb_ot_tags_from_script_and_language(hb_qt_script_to_script(script), HB_LANGUAGE_INVALID,
-                                                &script_count, script_tags,
-                                                nullptr, nullptr);
+        hb_ot_tags_from_script_and_language(hb_qt_script_to_script(script), HB_LANGUAGE_INVALID,
+                                            &script_count, script_tags,
+                                            nullptr, nullptr);
 
-            if (hb_ot_layout_table_select_script(face, HB_OT_TAG_GSUB, script_count, script_tags, nullptr, nullptr))
-                return true;
-        }
+        if (hb_ot_layout_table_select_script(face, HB_OT_TAG_GSUB, script_count, script_tags, nullptr, nullptr))
+            return true;
     }
 #endif
     return false;
diff --git a/src/gui/text/qtextengine.cpp b/src/gui/text/qtextengine.cpp
index 5548379778..97b9836856 100644
--- a/src/gui/text/qtextengine.cpp
+++ b/src/gui/text/qtextengine.cpp
@@ -1354,10 +1354,6 @@ void QTextEngine::shapeLine(const QScriptLine &line)
     }
 }
 
-#if QT_CONFIG(harfbuzz)
-extern bool qt_useHarfbuzzNG(); // defined in qfontengine.cpp
-#endif
-
 static void applyVisibilityRules(ushort ucs, QGlyphLayout *glyphs, uint glyphPosition, QFontEngine *fontEngine)
 {
     // hide characters that should normally be invisible
@@ -1517,7 +1513,7 @@ void QTextEngine::shapeText(int item) const
     }
 
 #if QT_CONFIG(harfbuzz)
-    if (Q_LIKELY(shapingEnabled && qt_useHarfbuzzNG())) {
+    if (Q_LIKELY(shapingEnabled)) {
         si.num_glyphs = shapeTextWithHarfbuzzNG(si, string, itemLength, fontEngine, itemBoundaries, kerningEnabled, letterSpacing != 0);
     } else
 #endif
@@ -1578,8 +1574,7 @@ void QTextEngine::shapeText(int item) const
     QGlyphLayout glyphs = shapedGlyphs(&si);
 
 #if QT_CONFIG(harfbuzz)
-    if (Q_LIKELY(qt_useHarfbuzzNG()))
-        qt_getJustificationOpportunities(string, itemLength, si, glyphs, logClusters(&si));
+    qt_getJustificationOpportunities(string, itemLength, si, glyphs, logClusters(&si));
 #endif
 
     if (letterSpacing != 0) {