Merge pull request #1009 from czgdp1807/dict04

Allow empty dict initialisation at declaration

Author: certik

integration_tests/test_dict_01.py

@@ -1,10 +1,12 @@
 from ltypes import i32, f64
 
 def test_dict():
-    rollnumber2cpi: dict[i32, f64] = {0: 1.1}
+    rollnumber2cpi: dict[i32, f64] = {}
     i: i32
     size: i32 = 1000
 
+    rollnumber2cpi[0] = 1.1
+
     for i in range(1000, 1000 + size):
         rollnumber2cpi[i] = float(i/100.0 + 5.0)
 

src/lpython/semantics/python_ast_to_asr.cpp

@@ -3328,6 +3328,11 @@ class BodyVisitor : public CommonVisitor<BodyVisitor> {
 
     void visit_Dict(const AST::Dict_t &x) {
         LFORTRAN_ASSERT(x.n_keys == x.n_values);
+        if( x.n_keys == 0 && ann_assign_target_type != nullptr ) {
+            tmp = ASR::make_DictConstant_t(al, x.base.base.loc, nullptr, 0,
+                                           nullptr, 0, ann_assign_target_type);
+            return ;
+        }
         Vec<ASR::expr_t*> keys;
         keys.reserve(al, x.n_keys);
         ASR::ttype_t* key_type = nullptr;