global and local syntax error

src/analysis/scoping_analysis.cpp

@@ -218,6 +218,7 @@ struct ScopingAnalysis::ScopeNameUsage {
     StrSet read;
     StrSet written;
     StrSet forced_globals;
+    StrSet params;
     std::vector<AST_Name*> del_name_nodes;
 
     // Properties determined by looking at other scopes as well:
@@ -439,14 +440,24 @@ private:
     };
 };
 
+static void raiseGlobalAndLocalException(InternedString name, AST* node) {
+    assert(node->type == AST_TYPE::FunctionDef);
+    AST_FunctionDef* funcNode = ast_cast<AST_FunctionDef>(node);
+    char buf[1024];
+    snprintf(buf, sizeof(buf), "name '%s' is local and global", name.c_str());
+    raiseSyntaxError(buf, funcNode->lineno, funcNode->col_offset, "" /* file?? */, funcNode->name.str());
+}
+
 class NameCollectorVisitor : public ASTVisitor {
 private:
     AST* orig_node;
     ScopingAnalysis::NameUsageMap* map;
     ScopingAnalysis::ScopeNameUsage* cur;
     ScopingAnalysis* scoping;
+    bool currently_visiting_functiondef_args;
+
     NameCollectorVisitor(AST* node, ScopingAnalysis::NameUsageMap* map, ScopingAnalysis* scoping)
-        : orig_node(node), map(map), scoping(scoping) {
+        : orig_node(node), map(map), scoping(scoping), currently_visiting_functiondef_args(false) {
         assert(map);
         cur = (*map)[node];
         assert(cur);
@@ -457,6 +468,9 @@ public:
         assert(name == mangleName(name, cur->private_name, scoping->getInternedStrings()));
         cur->read.insert(name);
         cur->written.insert(name);
+        if (this->currently_visiting_functiondef_args) {
+            cur->params.insert(name);
+        }
     }
 
     void doRead(InternedString name) {
@@ -549,6 +563,10 @@ public:
     bool visit_global(AST_Global* node) override {
         for (int i = 0; i < node->names.size(); i++) {
             mangleNameInPlace(node->names[i], cur->private_name, scoping->getInternedStrings());
+            if (cur->params.find(node->names[i]) != cur->params.end()) {
+                // Throw an exception if a name is both declared global and a parameter
+                raiseGlobalAndLocalException(node->names[i], this->orig_node);
+            }
             cur->forced_globals.insert(node->names[i]);
         }
         return true;
@@ -577,6 +595,8 @@ public:
 
     bool visit_functiondef(AST_FunctionDef* node) override {
         if (node == orig_node) {
+            this->currently_visiting_functiondef_args = true;
+
             int counter = 0;
             for (AST_expr* e : node->args->args) {
                 if (e->type == AST_TYPE::Tuple) {
@@ -594,6 +614,9 @@ public:
                 mangleNameInPlace(node->args->kwarg, cur->private_name, scoping->getInternedStrings());
                 doWrite(node->args->kwarg);
             }
+
+            this->currently_visiting_functiondef_args = false;
+
             for (AST_stmt* s : node->body)
                 s->accept(this);
             return true;

test/tests/global_and_local.py

-# expected: fail
 # - this particular check isn't implemented yet
 
 # I would have expected this to be valid, but cPython and pypy err out saying "name 'x' is local and global"
 
-print "first"
-
+try:
+    exec """
 x = 1
 def f(x):
     global x
@@ -12,3 +11,56 @@ def f(x):
 print "calling"
 f(2)
 print x
+"""
+except SyntaxError as e:
+    print e.message
+
+try:
+    exec """
+x = 1
+def f((x, y)):
+    global x
+
+print "calling"
+f(2)
+print x
+"""
+except SyntaxError as e:
+    print e.message
+
+try:
+    exec """
+def f(*args):
+    global args
+
+print "calling"
+f(2)
+print x
+"""
+except SyntaxError as e:
+    print e.message
+
+try:
+    exec """
+def f(*kwargs):
+    global kwargs
+
+print "calling"
+f(d=2)
+print x
+"""
+except SyntaxError as e:
+    print e.message
+
+try:
+    exec """
+class C(object):
+    def f(__a):
+        global __a
+
+print "calling"
+f(d=2)
+print x
+"""
+except SyntaxError as e:
+    print e.message