Added semantic error for float declaration. (lcompilers#2529)

* Add semantic error for float declaration & added tests for the same.

src/lpython/semantics/python_ast_to_asr.cpp

@@ -885,7 +885,16 @@ class CommonVisitor : public AST::BaseVisitor<Struct> {
                     })
                 );
                 throw SemanticAbort();
-            } else { 
+            } else if (var_annotation == "float") {
+                std::string msg = "Hint: Use f32 or f64 for now. ";
+                diag.add(diag::Diagnostic(
+                    var_annotation + " type is not supported yet. ",
+                    diag::Level::Error, diag::Stage::Semantic, {
+                        diag::Label(msg, {loc})
+                    })
+                );
+                throw SemanticAbort();
+            }  else {
                 throw SemanticError("The type '" + var_annotation+"' is undeclared.", loc);
             }
         }

tests/errors/test_float_semantic_error.py

@@ -0,0 +1,8 @@
+from lpython import f64
+
+def main0():
+    pi: float = 3.14
+    radi: f64 = 2.0
+    print("Area of Circle is", pi*radi**2)
+
+main0()

tests/reference/asr-test_float_semantic_error-58c0c90.json

@@ -0,0 +1,13 @@
+{
+    "basename": "asr-test_float_semantic_error-58c0c90",
+    "cmd": "lpython --show-asr --no-color {infile} -o {outfile}",
+    "infile": "tests/errors/test_float_semantic_error.py",
+    "infile_hash": "10929e3991a4aee1a2de473fc5f8caa48b6dcf4a35e2329a15ea5f1f",
+    "outfile": null,
+    "outfile_hash": null,
+    "stdout": null,
+    "stdout_hash": null,
+    "stderr": "asr-test_float_semantic_error-58c0c90.stderr",
+    "stderr_hash": "c11166fb86be513e74796a51f5c9e84653c2eb894ed95d502ed8af57",
+    "returncode": 2
+}

tests/reference/asr-test_float_semantic_error-58c0c90.stderr

@@ -0,0 +1,5 @@
+semantic error: float type is not supported yet. 
+ --> tests/errors/test_float_semantic_error.py:4:9
+  |
+4 |     pi: float = 3.14
+  |         ^^^^^ Hint: Use f32 or f64 for now. 

tests/tests.toml

@@ -1104,6 +1104,10 @@ asr = true
 filename = "errors/test_int_semantic_error.py"
 asr = true
 
+[[test]]
+filename = "errors/test_float_semantic_error.py"
+asr = true
+
 [[test]]
 filename = "errors/generics_error_01.py"
 asr = true