`7dd03cc`

Skip comment lines between preprocessor continuations

The preprocessor's line-joining loop appended comment-only
lines (starting with !) to the logical line instead of skipping
them. This produced tokens like `character(*), parameter :: !>`
that the lexer then split into a truncated declaration plus a
stray comment, causing parse failures on valid Fortran like
stdlib_io_aux.f90's documented parameter lists.

Per F2018 6.3.2.4, comment lines and blank lines between
continuation lines must be ignored.

Authored by mfwolffe <wolffemf@dukes.jmu.edu> 2 weeks ago

SHA: 7dd03cc3c8ca5986853dd7b2a5a2d0df3b578fcc
Parents: 817221c
Tree: 5443ee8

1 changed file

Status	File	+	-
M	`src/preprocess/mod.rs`	8	5

src/preprocess/mod.rsmodified

                  while has_trailing_continuation(&logical_line) {
                      if i < raw_lines.len() {
                          let next = raw_lines[i].trim_start();
--                        // A directive between free-form continued lines must
--                        // remain its own logical line so conditional blocks
--                        // can be evaluated before later Fortran continuation.
                          if next.starts_with('#') {
                              break;
+                         }
--                        // Remove the trailing & from the code portion.
++                        // F2018 6.3.2.4: comment lines and blank lines
++                        // may appear between a continuation line and
++                        // its successor. Skip them without breaking
++                        // the continuation.
++                        if next.starts_with('!') || next.is_empty() {
++                            i += 1;
++                            continue;
++                        }
                          let amp_pos = find_code_trailing_ampersand(&logical_line).unwrap();
                          logical_line.truncate(amp_pos);
--                        // Consume the next line, skipping leading & if present.
                          let next = next.strip_prefix('&').unwrap_or(next);
                          logical_line.push_str(next);
                          i += 1;