Raise an error for issue pyccel#1339 (pyccel#1866)

Raise an error indicating that C should be used to mix scalar and array
return types (see pyccel#1339).

---------

Co-authored-by: Yaman Güçlü <[email protected]>

Author: EmilyBourne

CHANGELOG.md

@@ -47,6 +47,7 @@ All notable changes to this project will be documented in this file.
 -   #1836 : Move `epyccel` module to `pyccel.commands.epyccel` and add support for shortcut import `from pyccel import epyccel`.
 -   #1720 : functions with the `@inline` decorator are no longer exposed to Python in the shared library.
 -   #1720 : Error raised when incompatible arguments are passed to an `inlined` function is now fatal.
+-   #1866 : Raise a more informative error when mixing scalar and array return types.
 -   \[TESTS\] Filter out cast warnings in cast tests.
 -   \[INTERNALS\] `FunctionDef` is annotated when it is called, or at the end of the `CodeBlock` if it is never called.
 -   \[INTERNALS\] `InlinedFunctionDef` is only annotated if it is called.

pyccel/codegen/printing/fcode.py

@@ -1875,15 +1875,28 @@ def _print_LiteralString(self, expr):
         return ' // '.join(formatted_str)
 
     def _print_Interface(self, expr):
+        interface_funcs = expr.functions
+
+        example_func = interface_funcs[0]
+
         # ... we don't print 'hidden' functions
-        if expr.functions[0].is_inline:
+        if example_func.is_inline:
             return ''
 
+        if len(example_func.results) == 1:
+            if len(set(f.results[0].var.rank == 0 for f in interface_funcs)) != 1:
+                message = ("Fortran cannot yet handle a templated function returning either a scalar or an array. "
+                           "If you are using the terminal interface, please pass --language c, "
+                           "if you are using the interactive interfaces epyccel or lambdify, please pass language='c'. "
+                           "See https://github.com/pyccel/pyccel/issues/1339 to monitor the advancement of this issue.")
+                errors.report(message,
+                        severity='error', symbol=expr)
+
         name = self._print(expr.name)
-        if all(isinstance(f, FunctionAddress) for f in expr.functions):
-            funcs = expr.functions
+        if all(isinstance(f, FunctionAddress) for f in interface_funcs):
+            funcs = interface_funcs
         else:
-            funcs = [f for f in expr.functions if f is \
+            funcs = [f for f in interface_funcs if f is \
                     expr.point([FunctionCallArgument(a.var.clone('arg_'+str(i))) \
                         for i,a in enumerate(f.arguments)])]
 

pyccel/parser/semantic.py

@@ -4008,6 +4008,8 @@ def unpack(ann):
                     bound_class.add_new_method(func)
 
             new_semantic_funcs += [func]
+            if expr.python_ast:
+                func.set_current_ast(expr.python_ast)
 
         if function_call_args is not None and len(new_semantic_funcs) == 0:
             for args in annotated_args[:-1]:
@@ -4026,6 +4028,8 @@ def unpack(ann):
                 self.insert_function(f)
 
             new_semantic_funcs = Interface(interface_name, new_semantic_funcs, syntactic_node=expr)
+            if expr.python_ast:
+                new_semantic_funcs.set_current_ast(expr.python_ast)
             if cls_name:
                 bound_class.add_new_interface(new_semantic_funcs)
             self.insert_function(new_semantic_funcs)

tests/errors/codegen/fortran/FORTRAN_ALLOCATABLE_IN_EXPRESSION.py renamed to tests/errors/codegen/fortran_blocking/FORTRAN_ALLOCATABLE_IN_EXPRESSION.py

@@ -0,0 +1,7 @@
+# pylint: disable=missing-function-docstring, missing-module-docstring
+from pyccel.decorators import types
+
+@types('int')
+@types('int[:]')
+def f(a):
+    return a+3

tests/errors/codegen/fortran/randint.py renamed to tests/errors/codegen/fortran_blocking/randint.py

@@ -133,8 +133,8 @@ def test_semantic_non_blocking_developer_errors(f):
     error_mode.set_mode('user')
     assert errors.has_errors()
 
-@pytest.mark.parametrize("f",get_files_from_folder("codegen/fortran"))
-def test_codegen_errors(f):
+@pytest.mark.parametrize("f",get_files_from_folder("codegen/fortran_blocking"))
+def test_codegen_blocking_errors(f):
     # reset Errors singleton
     errors = Errors()
     errors.reset()
@@ -154,6 +154,26 @@ def test_codegen_errors(f):
 
     assert errors.has_errors()
 
+@pytest.mark.parametrize("f",get_files_from_folder("codegen/fortran_non_blocking"))
+def test_codegen_non_blocking_errors(f):
+    # reset Errors singleton
+    errors = Errors()
+    errors.reset()
+
+    pyccel = Parser(f)
+    ast = pyccel.parse()
+
+    settings = {}
+    ast = pyccel.annotate(**settings)
+
+    name = os.path.basename(f)
+    name = os.path.splitext(name)[0]
+
+    codegen = Codegen(ast, name, 'fortran')
+    codegen.printer.doprint(codegen.ast)
+
+    assert errors.has_errors()
+
 @pytest.mark.parametrize("f",get_files_from_folder("known_bugs"))
 def test_neat_errors_for_known_bugs(f):
     # reset Errors singleton