Fix preprocessor else and elif

CHANGELOG.md

@@ -29,6 +29,8 @@
 
 ### Fixed
 
+- Fixed preprocessor bug with `if` and `elif` conditionals
+  ([#322](https://github.com/fortran-lang/fortls/issues/322))
 - Fixed bug where type fields or methods were not detected if spaces were
   used around `%`
   ([#286](https://github.com/fortran-lang/fortls/issues/286))

fortls/parse_fortran.py

@@ -2090,6 +2090,7 @@ def replace_vars(line: str):
     pp_skips = []
     pp_defines = []
     pp_stack = []
+    pp_stack_group = []
     defs_tmp = pp_defs.copy()
     def_regexes = {}
     output_file = []
@@ -2135,25 +2136,49 @@ def replace_vars(line: str):
             # Closing/middle conditional statements
             inc_start = False
             exc_start = False
+            exc_continue = False
             if match.group(1) == "elif":
-                if pp_stack[-1][0] < 0:
-                    pp_stack[-1][0] = i + 1
-                    exc_start = True
+                if (not pp_stack_group) or (pp_stack_group[-1][0] != len(pp_stack)):
+                    # First elif statement for this elif group
+                    if pp_stack[-1][0] < 0:
+                        pp_stack_group.append([len(pp_stack), True])
+                    else:
+                        pp_stack_group.append([len(pp_stack), False])
+                if pp_stack_group[-1][1]:
+                    # An earlier if or elif in this group has been true
+                    exc_continue = True
+                    if pp_stack[-1][0] < 0:
+                        pp_stack[-1][0] = i + 1
+                elif eval_pp_if(line[match.end(1) :], defs_tmp):
+                    pp_stack[-1][1] = i + 1
+                    pp_skips.append(pp_stack.pop())
+                    pp_stack_group[-1][1] = True
+                    pp_stack.append([-1, -1])
+                    inc_start = True
                 else:
-                    if eval_pp_if(line[match.end(1) :], defs_tmp):
-                        pp_stack[-1][1] = i - 1
-                        pp_stack.append([-1, -1])
-                        inc_start = True
+                    exc_start = True
             elif match.group(1) == "else":
                 if pp_stack[-1][0] < 0:
                     pp_stack[-1][0] = i + 1
                     exc_start = True
+                elif (
+                    pp_stack_group
+                    and (pp_stack_group[-1][0] == len(pp_stack))
+                    and (pp_stack_group[-1][1])
+                ):
+                    # An earlier if or elif in this group has been true
+                    exc_continue = True
                 else:
                     pp_stack[-1][1] = i + 1
+                    pp_skips.append(pp_stack.pop())
+                    pp_stack.append([-1, -1])
                     inc_start = True
             elif match.group(1) == "endif":
+                if pp_stack_group and (pp_stack_group[-1][0] == len(pp_stack)):
+                    pp_stack_group.pop()
                 if pp_stack[-1][0] < 0:
                     pp_stack.pop()
+                    log.debug(f"{line.strip()} !!! Conditional TRUE/END({i + 1})")
                     continue
                 if pp_stack[-1][1] < 0:
                     pp_stack[-1][1] = i + 1
@@ -2164,6 +2189,8 @@ def replace_vars(line: str):
                     log.debug(f"{line.strip()} !!! Conditional TRUE({i + 1})")
                 elif exc_start:
                     log.debug(f"{line.strip()} !!! Conditional FALSE({i + 1})")
+                elif exc_continue:
+                    log.debug(f"{line.strip()} !!! Conditional EXCLUDED({i + 1})")
             continue
         # Handle variable/macro definitions files
         match = FRegex.PP_DEF.match(line)

test/test_preproc.py

@@ -30,6 +30,18 @@ def check_return(result_array, checks):
     string += hover_req(file_path, 10, 15)  # defined without ()
     file_path = root_dir / "preproc_keywords.F90"
     string += hover_req(file_path, 6, 2)  # ignores PP across Fortran line continuations
+    file_path = root_dir / "preproc_else.F90"
+    string += hover_req(file_path, 8, 12)
+    string += hover_req(file_path, 18, 12)
+    file_path = root_dir / "preproc_elif.F90"
+    string += hover_req(file_path, 22, 15)
+    string += hover_req(file_path, 24, 10)
+    file_path = root_dir / "preproc_elif_elif_skip.F90"
+    string += hover_req(file_path, 30, 23)
+    file_path = root_dir / "preproc_if_elif_else.F90"
+    string += hover_req(file_path, 30, 23)
+    file_path = root_dir / "preproc_if_elif_skip.F90"
+    string += hover_req(file_path, 30, 23)
     config = str(root_dir / ".pp_conf.json")
     errcode, results = run_request(string, ["--config", config])
     assert errcode == 0
@@ -49,6 +61,13 @@ def check_return(result_array, checks):
         ),
         "```fortran90\n#define SUCCESS .true.\n```",
         "```fortran90\nREAL, CONTIGUOUS, POINTER, DIMENSION(:) :: var1\n```",
+        "```fortran90\nINTEGER :: var0\n```",
+        "```fortran90\nREAL :: var1\n```",
+        "```fortran90\nINTEGER :: var2\n```",
+        "```fortran90\nINTEGER, INTENT(INOUT) :: var\n```",
+        "```fortran90\nINTEGER, PARAMETER :: res = 0+1+0+0\n```",
+        "```fortran90\nINTEGER, PARAMETER :: res = 0+0+0+1\n```",
+        "```fortran90\nINTEGER, PARAMETER :: res = 1+0+0+0\n```",
     )
     assert len(ref_results) == len(results) - 1
     check_return(results[1:], ref_results)

test/test_source/pp/preproc_elif.F90

@@ -0,0 +1,27 @@
+subroutine preprocessor_elif(var, var3, var4, var5, var6)
+
+! This file, as used in test_preproc, checks that
+! 1. the steps after the preprocessor parsing has fully finished, are only
+! using content from the parts within the preprocessor if-elif-else that
+! should be used. To do this, it has some regular fortran code within the
+! #if and #elif.
+! 2. the #endif correctly concludes the if-elif, so any new #define statements
+! that come after the #endif, are picked up during the preprocessor parsing.
+
+#if 0
+integer, intent(in) :: var
+#elif 1
+integer, intent(inout) :: var
+var = 3
+#else
+integer, intent(out) :: var
+var = 5
+#endif
+
+#define OTHERTYPE integer
+
+OTHERTYPE :: var2
+
+PRINT*, var
+
+endsubroutine preprocessor_elif

test/test_source/pp/preproc_elif_elif_skip.F90

@@ -0,0 +1,33 @@
+subroutine preprocessor_elif_elif_skip()
+
+! This file, as used in test_preproc, and together with the two similar files,
+! tests that when there is an if-elif-elif-else, only the first branch that
+! evaluates to true is used, and the others ignored. Also when multiple
+! conditions evaluate to true.
+
+#if 0
+#define PART1 0
+#elif 1
+#define PART2 1
+#elif 1
+#define PART3 0
+#else
+#define PART4 0
+#endif
+
+#ifndef PART1
+#define PART1 0
+#endif
+#ifndef PART2
+#define PART2 0
+#endif
+#ifndef PART3
+#define PART3 0
+#endif
+#ifndef PART4
+#define PART4 0
+#endif
+
+integer, parameter :: res = PART1+PART2+PART3+PART4
+
+end subroutine preprocessor_elif_elif_skip

test/test_source/pp/preproc_else.F90

@@ -0,0 +1,21 @@
+subroutine preprocessor_else(var)
+
+#if 0
+#define MYTYPE logical
+#else
+#define MYTYPE integer
+#endif
+
+MYTYPE :: var0
+
+#undef MYTYPE
+
+#if 1
+#define MYTYPE real
+#else
+#define MYTYPE character
+#endif
+
+MYTYPE :: var1
+
+endsubroutine preprocessor_else

test/test_source/pp/preproc_if_elif_else.F90

@@ -0,0 +1,33 @@
+subroutine preprocessor_if_elif_else()
+
+! This file, as used in test_preproc, and together with the two similar files,
+! tests that when there is an if-elif-elif-else, only the first branch that
+! evaluates to true is used, and the others ignored. Also when multiple
+! conditions evaluate to true.
+
+#if 0
+#define PART1 0
+#elif 0
+#define PART2 0
+#elif 0
+#define PART3 0
+#else
+#define PART4 1
+#endif
+
+#ifndef PART1
+#define PART1 0
+#endif
+#ifndef PART2
+#define PART2 0
+#endif
+#ifndef PART3
+#define PART3 0
+#endif
+#ifndef PART4
+#define PART4 0
+#endif
+
+integer, parameter :: res = PART1+PART2+PART3+PART4
+
+endsubroutine preprocessor_if_elif_else

test/test_source/pp/preproc_if_elif_skip.F90

@@ -0,0 +1,33 @@
+subroutine preprocessor_if_elif_skip()
+
+! This file, as used in test_preproc, and together with the two similar files,
+! tests that when there is an if-elif-elif-else, only the first branch that
+! evaluates to true is used, and the others ignored. Also when multiple
+! conditions evaluate to true.
+
+#if 1
+#define PART1 1
+#elif 0
+#define PART2 0
+#elif 1
+#define PART3 0
+#else
+#define PART4 0
+#endif
+
+#ifndef PART1
+#define PART1 0
+#endif
+#ifndef PART2
+#define PART2 0
+#endif
+#ifndef PART3
+#define PART3 0
+#endif
+#ifndef PART4
+#define PART4 0
+#endif
+
+integer, parameter :: res = PART1+PART2+PART3+PART4
+
+end subroutine preprocessor_if_elif_skip