Fix lookup of enums declared in QML singletons

Given the following expression

    var x = MySingleton.MyEnumValue

where MySingleton is a QML (composite) singleton and MyEnumValue comes
from a QML declared enum, we had code in place up to (and including)
5.10 to attempt to optimize that expression to a enum constant at
compile time. In 5.10 that optimization does not exist anymore. In <=
5.10 we would also skip the optimization under certain circumstances
(too many statementes, etc.). The fallback that is in place for handling
this at run-time tried to be smart by avoiding the
QQmlContextWrapper::get lookup and return straight a reference to the
singleton as QObject. That works for regular property lookups, but it
fails when trying to look up something like an enum, that isn't a
meta-object property.

Change-Id: I1819b9d8ae06a3f595e067bf5b018c4065be76bb
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

4 files changed, 3 insertions, 15 deletions

diff --git a/src/qml/compiler/qqmlirbuilder.cpp b/src/qml/compiler/qqmlirbuilder.cpp
index 237cd9bf3b..a9d86b24f5 100644
--- a/src/qml/compiler/qqmlirbuilder.cpp
+++ b/src/qml/compiler/qqmlirbuilder.cpp
@@ -2213,12 +2213,6 @@ QV4::Compiler::Codegen::Reference JSCodeGen::fallbackNameLookup(const QString &n
                 Reference imports = Reference::fromStackSlot(this, _importedScriptsSlot);
                 return Reference::fromSubscript(imports, Reference::fromConst(this, QV4::Encode(r.scriptIndex)));
             } else if (r.type.isValid()) {
-                if (r.type.isCompositeSingleton()) {
-                    Instruction::LoadQmlSingleton load;
-                    load.name = registerString(name);
-                    bytecodeGenerator->addInstruction(load);
-                    return Reference::fromAccumulator(this);
-                }
                 return Reference::fromName(this, name);
             } else {
                 Q_ASSERT(r.importNamespace);
diff --git a/src/qml/compiler/qv4compileddata_p.h b/src/qml/compiler/qv4compileddata_p.h
index 2c0320f7f1..f1776f5772 100644
--- a/src/qml/compiler/qv4compileddata_p.h
+++ b/src/qml/compiler/qv4compileddata_p.h
@@ -72,7 +72,7 @@
 QT_BEGIN_NAMESPACE
 
 // Bump this whenever the compiler data structures change in an incompatible way.
-#define QV4_DATA_STRUCTURE_VERSION 0x17
+#define QV4_DATA_STRUCTURE_VERSION 0x18
 
 class QIODevice;
 class QQmlPropertyCache;
diff --git a/src/qml/compiler/qv4instr_moth.cpp b/src/qml/compiler/qv4instr_moth.cpp
index 34953d52ce..450fa50528 100644
--- a/src/qml/compiler/qv4instr_moth.cpp
+++ b/src/qml/compiler/qv4instr_moth.cpp
@@ -634,10 +634,6 @@ void dumpBytecode(const char *code, int len, int nLocals, int nFormals, int /*st
         MOTH_BEGIN_INSTR(LoadQmlImportedScripts)
             d << dumpRegister(result, nFormals);
         MOTH_END_INSTR(LoadQmlImportedScripts)
-
-        MOTH_BEGIN_INSTR(LoadQmlSingleton)
-            d << name;
-        MOTH_END_INSTR(LoadQmlSingleton)
     }
 }
 
diff --git a/src/qml/compiler/qv4instr_moth_p.h b/src/qml/compiler/qv4instr_moth_p.h
index 2d1428bd19..7dd639c94c 100644
--- a/src/qml/compiler/qv4instr_moth_p.h
+++ b/src/qml/compiler/qv4instr_moth_p.h
@@ -174,7 +174,6 @@ QT_BEGIN_NAMESPACE
 #define INSTR_Sub(op) INSTRUCTION(op, Sub, 1, lhs)
 #define INSTR_LoadQmlContext(op) INSTRUCTION(op, LoadQmlContext, 1, result)
 #define INSTR_LoadQmlImportedScripts(op) INSTRUCTION(op, LoadQmlImportedScripts, 1, result)
-#define INSTR_LoadQmlSingleton(op) INSTRUCTION(op, LoadQmlSingleton, 1, name)
 
 
 #define FOR_EACH_MOTH_INSTR(F) \
@@ -290,9 +289,8 @@ QT_BEGIN_NAMESPACE
     F(Mod) \
     F(Sub) \
     F(LoadQmlContext) \
-    F(LoadQmlImportedScripts) \
-    F(LoadQmlSingleton)
-#define MOTH_NUM_INSTRUCTIONS() (static_cast<int>(Moth::Instr::Type::LoadQmlSingleton) + 1)
+    F(LoadQmlImportedScripts)
+#define MOTH_NUM_INSTRUCTIONS() (static_cast<int>(Moth::Instr::Type::LoadQmlImportedScripts) + 1)
 
 #if defined(Q_CC_GNU) && !defined(Q_CC_INTEL)
 // icc before version 1200 doesn't support computed goto, and at least up to version 18.0.0 the