Fix support for default exports in modules

Default export declarations require a binding setup step at run-time, so
we hook it into the ESModule's statement list to make it visible to the
code gen visitor.

We also reserve local slot zero for the default export.

Change-Id: Ie064caad0422b92cfdadbd7d94db72a05e95c0cc
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

8 files changed, 87 insertions, 21 deletions

diff --git a/src/qml/compiler/qv4codegen.cpp b/src/qml/compiler/qv4codegen.cpp
index 7b059b3fb4..fc43031c5c 100644
--- a/src/qml/compiler/qv4codegen.cpp
+++ b/src/qml/compiler/qv4codegen.cpp
@@ -789,6 +789,36 @@ bool Codegen::visit(PatternPropertyList *)
     return false;
 }
 
+bool Codegen::visit(ExportDeclaration *ast)
+{
+    if (!ast->exportDefault)
+        return true;
+
+    Reference exportedValue;
+
+    if (auto *fdecl = AST::cast<FunctionDeclaration*>(ast->variableStatementOrDeclaration)) {
+        Result r;
+        qSwap(_expr, r);
+        visit(static_cast<FunctionExpression*>(fdecl));
+        qSwap(_expr, r);
+        exportedValue = r.result();
+    } else if (auto *classDecl = AST::cast<ClassDeclaration*>(ast->variableStatementOrDeclaration)) {
+        Result r;
+        qSwap(_expr, r);
+        visit(static_cast<ClassExpression*>(classDecl));
+        qSwap(_expr, r);
+        exportedValue = r.result();
+    } else if (ExpressionNode *expr = ast->variableStatementOrDeclaration->expressionCast()) {
+        exportedValue = expression(expr);
+    }
+
+    exportedValue.loadInAccumulator();
+    Reference defaultExportSlot = Reference::fromScopedLocal(this, 0, /*scope*/0);
+    defaultExportSlot.storeConsumeAccumulator();
+
+    return false;
+}
+
 bool Codegen::visit(StatementList *)
 {
     Q_UNREACHABLE();
diff --git a/src/qml/compiler/qv4codegen_p.h b/src/qml/compiler/qv4codegen_p.h
index e3617254a7..516f506396 100644
--- a/src/qml/compiler/qv4codegen_p.h
+++ b/src/qml/compiler/qv4codegen_p.h
@@ -589,6 +589,8 @@ protected:
     bool visit(AST::PatternProperty *ast) override;
     bool visit(AST::PatternPropertyList *ast) override;
 
+    bool visit(AST::ExportDeclaration *ast) override;
+
     // expressions
     bool visit(AST::Expression *ast) override;
     bool visit(AST::ArrayPattern *ast) override;
diff --git a/src/qml/compiler/qv4compilercontext.cpp b/src/qml/compiler/qv4compilercontext.cpp
index 77ac703ee3..c0fbb72c59 100644
--- a/src/qml/compiler/qv4compilercontext.cpp
+++ b/src/qml/compiler/qv4compilercontext.cpp
@@ -295,6 +295,11 @@ void Context::setupFunctionIndices(Moth::BytecodeGenerator *bytecodeGenerator)
     Q_ASSERT(nRegisters == 0);
     registerOffset = bytecodeGenerator->currentRegister();
 
+    if (contextType == ContextType::ESModule && hasDefaultExport) {
+        // allocate a local slot for the default export
+        locals.append(QStringLiteral("*default*"));
+    }
+
     switch (contextType) {
     case ContextType::ESModule:
     case ContextType::Block:
diff --git a/src/qml/compiler/qv4compilercontext_p.h b/src/qml/compiler/qv4compilercontext_p.h
index 6a54be2aca..216d5ca56b 100644
--- a/src/qml/compiler/qv4compilercontext_p.h
+++ b/src/qml/compiler/qv4compilercontext_p.h
@@ -178,6 +178,7 @@ struct Context {
     QStringList locals;
     QVector<ImportEntry> importEntries;
     QVector<ExportEntry> exportEntries;
+    bool hasDefaultExport = false;
     QVector<Context *> nestedContexts;
 
     ControlFlow *controlFlow = nullptr;
diff --git a/src/qml/compiler/qv4compilerscanfunctions.cpp b/src/qml/compiler/qv4compilerscanfunctions.cpp
index 63ed748048..8f16f9a362 100644
--- a/src/qml/compiler/qv4compilerscanfunctions.cpp
+++ b/src/qml/compiler/qv4compilerscanfunctions.cpp
@@ -201,21 +201,30 @@ bool ScanFunctions::visit(ExportDeclaration *declaration)
         }
     } else if (auto *classDecl = AST::cast<AST::ClassDeclaration*>(declaration->variableStatementOrDeclaration)) {
         QString name = classDecl->name.toString();
-        Compiler::ExportEntry entry;
-        entry.localName = name;
-        entry.exportName = name;
-        _context->exportEntries << entry;
+        if (!name.isEmpty()) {
+            Compiler::ExportEntry entry;
+            entry.localName = name;
+            entry.exportName = name;
+            _context->exportEntries << entry;
+        }
     } else if (auto *fdef = declaration->variableStatementOrDeclaration->asFunctionDefinition()) {
         QString name = fdef->name.toString();
-        Compiler::ExportEntry entry;
-        entry.localName = name;
-        entry.exportName = name;
-        _context->exportEntries << entry;
-    } else if (declaration->exportDefault) {
+        // Our parser gives `export default (function() {}` the name "default", which
+        // we don't want to export here.
+        if (!name.isEmpty() && name != QStringLiteral("default")) {
+            Compiler::ExportEntry entry;
+            entry.localName = name;
+            entry.exportName = name;
+            _context->exportEntries << entry;
+        }
+    }
+
+    if (declaration->exportDefault) {
         Compiler::ExportEntry entry;
         entry.localName = QStringLiteral("*default*");
         entry.exportName = QStringLiteral("default");
         _context->exportEntries << entry;
+        _context->hasDefaultExport = true;
     }
 
     return true; // scan through potential assignment expression code, etc.
diff --git a/src/qml/parser/qqmljs.g b/src/qml/parser/qqmljs.g
index 4c5748f818..faf465e7b9 100644
--- a/src/qml/parser/qqmljs.g
+++ b/src/qml/parser/qqmljs.g
@@ -3991,7 +3991,7 @@ ScriptBody: StatementList;
 
 Module: ModuleBodyOpt;
 /.  case $rule_number: {
-        sym(1).Node = new (pool) AST::ESModule(sym(1).ModuleItemList);
+        sym(1).Node = new (pool) AST::ESModule(sym(1).ModuleItemList, pool);
     } break;
 ./
 
@@ -4233,6 +4233,14 @@ ExportDeclaration: T_EXPORT T_DEFAULT ExportDeclarationLookahead T_FORCE_DECLARA
 ExportDeclaration: T_EXPORT T_DEFAULT ExportDeclarationLookahead AssignmentExpression_In; -- [lookahead ∉ { function, class }]
 /.
     case $rule_number: {
+        // if lhs is an identifier expression and rhs is an anonymous function expression, we need to assign the name of lhs to the function
+        if (auto *f = asAnonymousFunctionDefinition(sym(4).Node)) {
+            f->name = stringRef(2);
+        }
+        if (auto *c = asAnonymousClassDefinition(sym(4).Expression)) {
+            c->name = stringRef(2);
+        }
+
         auto exportDeclaration = new (pool) AST::ExportDeclaration(/*exportDefault=*/true, sym(4).Node);
         exportDeclaration->exportToken = loc(1);
         sym(1).ExportDeclaration = exportDeclaration;
diff --git a/src/qml/parser/qqmljsast.cpp b/src/qml/parser/qqmljsast.cpp
index 6b315c9140..0b1b97a41a 100644
--- a/src/qml/parser/qqmljsast.cpp
+++ b/src/qml/parser/qqmljsast.cpp
@@ -1166,10 +1166,17 @@ void ModuleItemList::accept0(Visitor *visitor)
 {
     if (visitor->visit(this)) {
         for (ModuleItemList *it = this; it; it = it->next) {
-            // The statement list is concatenated together between module list
-            // items and stored in the ESModule, thus not visited from there.
-            if (it->item && it->item->kind == Kind_StatementList)
-                continue;
+            if (it->item) {
+                // The statement list is concatenated together between module list
+                // items and stored in the ESModule, thus not visited from there.
+                if (it->item->kind == Kind_StatementList)
+                    continue;
+                // Export declaration are also injected into the statement list for
+                // processing of declarations an variable statements, so don't visit
+                // it here to avoid double visits.
+                if (it->item->kind == Kind_ExportDeclaration)
+                    continue;
+            }
             accept(it->item, visitor);
         }
     }
@@ -1177,13 +1184,17 @@ void ModuleItemList::accept0(Visitor *visitor)
     visitor->endVisit(this);
 }
 
-StatementList *ModuleItemList::buildStatementList() const
+StatementList *ModuleItemList::buildStatementList(MemoryPool *pool) const
 {
     StatementList *statements = nullptr;
     for (const ModuleItemList *item = this; item; item = item->next) {
         AST::StatementList *listItem = AST::cast<AST::StatementList*>(item->item);
-        if (!listItem)
-            continue;
+        if (!listItem) {
+            if (AST::ExportDeclaration *exportDecl = AST::cast<AST::ExportDeclaration*>(item->item))
+                listItem = new (pool) AST::StatementList(exportDecl);
+            else
+                continue;
+        }
         if (statements)
             statements = statements->append(listItem);
         else
diff --git a/src/qml/parser/qqmljsast_p.h b/src/qml/parser/qqmljsast_p.h
index 0729c99931..9d82e9546b 100644
--- a/src/qml/parser/qqmljsast_p.h
+++ b/src/qml/parser/qqmljsast_p.h
@@ -2675,7 +2675,7 @@ public:
     ExportsList *exportsList = nullptr;
 };
 
-class QML_PARSER_EXPORT ExportDeclaration: public Node
+class QML_PARSER_EXPORT ExportDeclaration: public Statement
 {
 public:
     QQMLJS_DECLARE_AST_NODE(ExportDeclaration)
@@ -2753,7 +2753,7 @@ public:
         return head;
     }
 
-    StatementList *buildStatementList() const;
+    StatementList *buildStatementList(MemoryPool *pool) const;
 
     void accept0(Visitor *visitor) override;
 
@@ -2773,12 +2773,12 @@ class QML_PARSER_EXPORT ESModule: public Node
 public:
     QQMLJS_DECLARE_AST_NODE(Module)
 
-    ESModule(ModuleItemList *body)
+    ESModule(ModuleItemList *body, MemoryPool *pool)
         : body(body)
     {
         kind = K;
         if (body)
-            statements = body->buildStatementList();
+            statements = body->buildStatementList(pool);
     }
 
     void accept0(Visitor *visitor) override;