Allows for externals to be split across multiple lines

Fixes multiple declarations for external functions #169

Unittests have been added

Author: gnikit

CHANGELOG.md

@@ -10,6 +10,7 @@
 - Adds intrinsic support for `OpenACC` version 3.1
 - Adds sphinx autogenerated documentation
 - Adds `incl_suffixes` as a configuration option
+- Adds `EXTERNAL` as an attribute upon hover
 
 ### Changes
 
@@ -21,6 +22,8 @@
 - Fixes the hover of preprocessor functions. It now displays the function name
   witout the argument list and the function body. The argument list cannot be
   multiline but the function body can.
+- Fixes objects marked `EXTERNAL` across multiple lines
+  ([#169](https://github.com/hansec/fortran-language-server/issues/169))
 
 ## 1.16.0
 

fortls/constants.py

@@ -26,6 +26,7 @@
     "elemental",
     "recursive",
     "abstract",
+    "external",
 ]
 KEYWORD_ID_DICT = {keyword: ind for (ind, keyword) in enumerate(KEYWORD_LIST)}
 

fortls/objects.py

@@ -1561,6 +1561,7 @@ def base_setup(
         self.link_obj = None
         self.type_obj = None
         self.is_const: bool = False
+        self.is_external: bool = False
         self.param_val: str = None
         self.link_name: str = None
         self.FQSN: str = self.name.lower()
@@ -1574,6 +1575,11 @@ def base_setup(
             self.vis = -1
         if self.keywords.count(KEYWORD_ID_DICT["parameter"]) > 0:
             self.is_const = True
+        if (
+            self.keywords.count(KEYWORD_ID_DICT["external"]) > 0
+            or self.desc.lower() == "external"
+        ):
+            self.is_external = True
 
     def update_fqsn(self, enc_scope=None):
         if enc_scope is not None:
@@ -1665,6 +1671,10 @@ def is_parameter(self):
     def set_parameter_val(self, val: str):
         self.param_val = val
 
+    def set_external_attr(self):
+        self.keywords.append(KEYWORD_ID_DICT["external"])
+        self.is_external = True
+
     def check_definition(self, obj_tree, known_types={}, interface=False):
         # Check for type definition in scope
         type_match = DEF_KIND_REGEX.match(self.desc)
@@ -1871,6 +1881,7 @@ def __init__(self, file_obj=None):
         self.parse_errors: list = []
         self.inherit_objs: list = []
         self.linkable_objs: list = []
+        self.external_objs: list = []
         self.none_scope = None
         self.inc_scope = None
         self.current_scope = None
@@ -1945,12 +1956,14 @@ def end_scope(self, line_number: int, check: bool = True):
             self.END_SCOPE_REGEX = None
         self.enc_scope_name = self.get_enc_scope_name()
 
-    def add_variable(self, new_var):
+    def add_variable(self, new_var: fortran_var):
         if self.current_scope is None:
             self.create_none_scope()
             new_var.FQSN = self.none_scope.FQSN + "::" + new_var.name.lower()
         self.current_scope.add_child(new_var)
         self.variable_list.append(new_var)
+        if new_var.is_external:
+            self.external_objs.append(new_var)
         if new_var.require_link():
             self.linkable_objs.append(new_var)
         self.last_obj = new_var

fortls/parse_fortran.py

@@ -664,6 +664,107 @@ def read_vis_stmnt(line: str):
 ]
 
 
+def find_external_type(
+    file_ast: fortran_ast, desc_string: str, name_stripped: str
+) -> bool:
+    """Encountered a variable with EXTERNAL as its type
+    Try and find an already defined variable with a
+    NORMAL Fortran Type"""
+    if not desc_string.upper() == "EXTERNAL":
+        return False
+    counter = 0
+    # Definition without EXTERNAL has already been parsed
+    for v in file_ast.variable_list:
+        if name_stripped == v.name:
+            # If variable is already in external objs it has
+            # been parsed correctly so exit
+            if v in file_ast.external_objs:
+                return False
+
+            v.set_external_attr()
+            file_ast.external_objs.append(v)
+            counter += 1
+            # TODO: do I need to update AST any more?
+    if counter == 1:
+        return True
+    else:
+        return False
+
+
+def find_external_attr(
+    file_ast: fortran_ast, name_stripped: str, new_var: fortran_var
+) -> bool:
+    """Check if this NORMAL Fortran variable is in the
+    external_objs with only EXTERNAL as its type"""
+    counter = 0
+    for v in file_ast.external_objs:
+        if v.name != name_stripped:
+            continue
+        if v.desc.upper() != "EXTERNAL":
+            continue
+        # We do this once
+        if counter == 0:
+            v.desc = new_var.desc
+            v.set_external_attr()
+        # TODO: do i need to update AST any more?
+        counter += 1
+
+    # Only one definition encountered
+    if counter == 1:
+        return True
+    # If no variable or multiple variables add to AST.
+    # Multiple defs will throw diagnostic error as it should
+    else:
+        return False
+
+
+def find_external(
+    file_ast: fortran_ast,
+    desc_string: str,
+    name_stripped: str,
+    new_var: fortran_var,
+) -> bool:
+    """Find a procedure, function, subroutine, etc. that has been defined as
+    `EXTERNAL`. `EXTERNAL`s are parsed as `fortran_var`, since there is no
+    way of knowing if `real, external :: val` is a function or a subroutine.
+
+    This method exists solely for `EXTERNAL`s that are defined across multiple
+    lines e.g.
+    `EXTERNAL VAR`
+    `REAL VAR`
+
+    or
+
+    `REAL VAR`
+    `EXTERNAL VAR`
+
+
+    Parameters
+    ----------
+    file_ast : fortran_ast
+        AST
+    desc_string : str
+        Variable type e.g. `REAL`, `INTEGER`, `EXTERNAL`
+    name_stripped : str
+        Variable name
+    new_var : fortran_var
+        The line variable that we are attempting to match with an `EXTERNAL`
+        definition
+
+    Returns
+    -------
+    bool
+        True if the variable is `EXTERNAL` and we manage to link it to the
+        rest of its components, else False
+    """
+    if find_external_type(file_ast, desc_string, name_stripped):
+        return True
+    elif desc_string.upper() != "EXTERNAL":
+        if find_external_attr(file_ast, name_stripped, new_var):
+            return True
+    return False
+
+
 class fortran_file:
     def __init__(self, path: str = None, pp_suffixes: list = None):
         self.path: str = path
@@ -1607,6 +1708,12 @@ def parser_debug_msg(msg: str, line: str, ln: int):
                             if match:
                                 var = match.group(1).strip()
                                 new_var.set_parameter_val(var)
+
+                        # Check if the "variable" is external and if so cycle
+                        if find_external(file_ast, desc_string, name_stripped, new_var):
+                            continue
+
+                    # if not merge_external:
                     file_ast.add_variable(new_var)
                 parser_debug_msg("VARIABLE", line, line_number)
 

fortls/regex_patterns.py

@@ -63,15 +63,15 @@
 NAT_VAR_REGEX = re.compile(
     r"[ ]*(INTEGER|REAL|DOUBLE[ ]*PRECISION|COMPLEX"
     r"|DOUBLE[ ]*COMPLEX|CHARACTER|LOGICAL|PROCEDURE"
-    r"|EXTERNAL|CLASS|TYPE)",
+    r"|EXTERNAL|CLASS|TYPE)",  # external :: variable is handled by this
     re.I,
 )
 KIND_SPEC_REGEX = re.compile(r"[ ]*([*]?\([ ]*[a-z0-9_*:]|\*[ ]*[0-9:]*)", re.I)
 KEYWORD_LIST_REGEX = re.compile(
     r"[ ]*,[ ]*(PUBLIC|PRIVATE|ALLOCATABLE|"
     r"POINTER|TARGET|DIMENSION\(|"
     r"OPTIONAL|INTENT\([inout]*\)|DEFERRED|NOPASS|"
-    r"PASS\([a-z0-9_]*\)|SAVE|PARAMETER|"
+    r"PASS\([a-z0-9_]*\)|SAVE|PARAMETER|EXTERNAL|"
     r"CONTIGUOUS)",
     re.I,
 )

test/test_server.py

@@ -175,6 +175,7 @@ def check_return(result_array):
         objs = (
             ["test", 6, 7],
             ["test_abstract", 2, 0],
+            ["test_external", 2, 0],
             ["test_free", 2, 0],
             ["test_gen_type", 5, 1],
             ["test_generic", 2, 0],
@@ -586,6 +587,11 @@ def test_diagnostics():
     """
     Tests some aspects of diagnostics
     """
+
+    def check_return(results, ref_results):
+        for i, r in enumerate(results):
+            assert r["diagnostics"] == ref_results[i]
+
     string = write_rpc_request(1, "initialize", {"rootPath": test_dir})
     # Test subroutines and functions with interfaces as arguments
     file_path = os.path.join(test_dir, "test_diagnostic_int.f90")
@@ -607,10 +613,64 @@ def test_diagnostics():
     string += write_rpc_notification(
         "textDocument/didOpen", {"textDocument": {"uri": file_path}}
     )
+    # Test that externals can be split between multiple lines
+    # and that diagnostics for multiple definitions of externals can account
+    # for that
+    file_path = os.path.join(test_dir, "diag", "test_external.f90")
+    string += write_rpc_notification(
+        "textDocument/didOpen", {"textDocument": {"uri": file_path}}
+    )
     errcode, results = run_request(string)
     assert errcode == 0
-    # check that the diagnostics list is empty
-    assert not results[1]["diagnostics"]
+    ref_results = [
+        [],
+        [],
+        [],
+        [],
+        [
+            {
+                "range": {
+                    "start": {"line": 7, "character": 17},
+                    "end": {"line": 7, "character": 22},
+                },
+                "message": 'Variable "VAR_B" declared twice in scope',
+                "severity": 1,
+                "relatedInformation": [
+                    {
+                        "location": {
+                            "uri": f"file://{file_path}",
+                            "range": {
+                                "start": {"line": 5, "character": 0},
+                                "end": {"line": 5, "character": 0},
+                            },
+                        },
+                        "message": "First declaration",
+                    }
+                ],
+            },
+            {
+                "range": {
+                    "start": {"line": 8, "character": 17},
+                    "end": {"line": 8, "character": 22},
+                },
+                "message": 'Variable "VAR_A" declared twice in scope',
+                "severity": 1,
+                "relatedInformation": [
+                    {
+                        "location": {
+                            "uri": f"file://{file_path}",
+                            "range": {
+                                "start": {"line": 3, "character": 0},
+                                "end": {"line": 3, "character": 0},
+                            },
+                        },
+                        "message": "First declaration",
+                    }
+                ],
+            },
+        ],
+    ]
+    check_return(results[1:], ref_results)
 
 
 if __name__ == "__main__":

test/test_source/diag/test_external.f90

@@ -0,0 +1,11 @@
+program test_external
+    implicit none
+    REAL, EXTERNAL :: VAL
+    REAL         VAR_A
+    EXTERNAL     VAR_A
+    EXTERNAL     VAR_B
+    REAL         VAR_B
+    EXTERNAL     VAR_B   ! throw error
+    REAL         VAR_A   ! throw error
+    EXTERNAL     VAR_C
+end program test_external