Bug: Incompatible return type in org-babel C when using a table of doubles with a header as a variable [9.4.4 (release_9.4.4-272-ga9f38b @ /home/richard/.emacs.d/straight/build/org/)]

[Richard Sent via "General discussions about Org-mode." <emacs-orgmode@gnu.org>]

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When a table of floating pointer numbers that contains a header row is
set as a variable to a C source block, the generated header file
contains an invalid return type, causing the program to not compile.

For example, if I have a table that looks like

#+NAME: tbl-doubles-org-bug-report
#+begin_src C :includes <stdio.h> :results table :colnames '("i" "val")
  for (int i = 0; i < 5; i++) {
    printf("%f %f\n", (double)i, i * 2.0);
  }
#+end_src

#+RESULTS: tbl-doubles-org-bug-report
|   i | val |
|-----+-----|
| 0.0 | 0.0 |
| 1.0 | 2.0 |
| 2.0 | 4.0 |
| 3.0 | 6.0 |
| 4.0 | 8.0 |

And then attempt to include that table as a variable called data

#+begin_src C :includes stdio.h :var data=tbl-doubles-org-bug-report
  printf("No errors!");
#+end_src

Nothing is printed, and *Org-Babel Error Output* will display

/tmp/babel-NQHi51/C-src-lsA892.c: In function ‘data_h’:
/tmp/babel-NQHi51/C-src-lsA892.c:24:65: error: incompatible types when returning type ‘double’ but ‘const char *’ was expected
   24 | const char* data_h (int row, const char* col) { return data[row][get_column_num(2,data_header,col)]; }
      |                                                        ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/bin/bash: line 1: /tmp/babel-NQHi51/C-bin-90Zk27: Permission denied

If we look in the /tmp file mentioned, it's easy to see the
inconsistency.

double data[5][2] = {
{0.000000,0.000000},
{1.000000,2.000000},
{2.000000,4.000000},
{3.000000,6.000000},
{4.000000,8.000000}
};
const int data_rows = 5;
const int data_cols = 2;
int get_column_num (int nbcols, const char** header, const char* column)
{
  int c;
  for (c=0; c<nbcols; c++)
    if (strcmp(header[c],column)==0)
      return c;
  return -1;
}
const char* data_header[2] = {"i","val"};
const char* data_h (int row, const char* col) { return
data[row][get_column_num(2,data_header,col)]; }
int main() {
printf("No errors!");
return 0;
}

data_h() should not return a const char*, but a double.

I've also tested this with $ emacs -Q and the issue is still present. It
does not occur if the table contains integer values instead of floats
or if a header row is omitted. Seeing as how the header row is processed
differently from the data, I don't think the presence of a header row is
meant to cause this error.



Emacs  : GNU Emacs 27.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.22, cairo version 1.17.3)
of 2020-08-28
Package: Org mode version 9.4.4 (release_9.4.4-272-ga9f38b @ /home/richard/.emacs.d/straight/build/org/)

current state:
==============
(setq
org-src-mode-hook '(org-src-babel-configure-edit-buffer org-src-mode-configure-edit-buffer doom-modeline-set-org-src-modeline)
org-link-shell-confirm-function 'yes-or-no-p
org-blank-before-new-entry '((heading . t) (plain-list-item . t))
org-metadown-hook '(org-babel-pop-to-session-maybe)
org-clock-out-hook '(org-clock-remove-empty-clock-drawer)
org-html-format-inlinetask-function 'org-html-format-inlinetask-default-function
org-odt-format-headline-function 'org-odt-format-headline-default-function
org-agenda-files '("~/org")
org-ascii-format-inlinetask-function 'org-ascii-format-inlinetask-default
org-startup-folded t
org-mode-hook '(#[0 "\301\211\x10\207" [imenu-create-index-function org-imenu-get-tree] 2]
#[0 "\300\301\302\303\304$\207" [add-hook change-major-mode-hook org-show-all append local] 5]
#[0 "\300\301\302\303\304$\207" [add-hook change-major-mode-hook org-babel-show-result-all append local] 5]
org-babel-result-hide-spec org-babel-hide-all-hashes turn-on-auto-fill mixed-pitch-mode org-superstar-mode
highlight-parentheses-mode)
org-odt-format-drawer-function #[514 "\207" [] 3 "\n\n(fn NAME CONTENTS)"]
org-archive-hook '(org-attach-archive-delete-maybe)
org-confirm-elisp-link-function 'yes-or-no-p
org-agenda-before-write-hook '(org-agenda-add-entry-text)
org-metaup-hook '(org-babel-load-in-session-maybe)
org-bibtex-headline-format-function #[257 "\300\x01\236A\207" [:title] 3 "\n\n(fn ENTRY)"]
org-adapt-indentation nil
org-latex-format-drawer-function #[514 "\207" [] 3 "\n\n(fn _ CONTENTS)"]
org-babel-pre-tangle-hook '(save-buffer)
org-file-apps '(("\\.pdf\\'" . emacs) (auto-mode . emacs) (directory . emacs) ("\\.mm\\'" . default) ("\\.x?html?\\'" . default)
("\\.pdf\\'" . default))
org-tab-first-hook '(org-babel-hide-result-toggle-maybe org-babel-header-arg-expand)
org-hide-leading-stars t
org-babel-load-languages '((C . t) (emacs-lisp . t))
org-log-done 'time
org-superstar-leading-bullet 32
org-ascii-format-drawer-function #[771 "\x01\207" [] 4 "\n\n(fn NAME CONTENTS WIDTH)"]
org-agenda-loop-over-headlines-in-active-region nil
org-occur-hook '(org-first-headline-recenter)
org-cycle-separator-lines 1
org-export-before-processing-hook '(org-blackfriday--reset-org-blackfriday--code-block-num-backticks)
org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers org-cycle-show-empty-lines
  org-optimize-window-after-visibility-change)
org-speed-command-hook '(org-speed-command-activate org-babel-speed-command-activate)
org-clock-persist-file "/home/richard/.emacs.d/var/org/clock-persist.el"
org-superstar-leading-fallback 8229
org-odt-format-inlinetask-function 'org-odt-format-inlinetask-default-function
org-latex-prefer-user-labels t
org-babel-tangle-lang-exts '(("D" . "d") ("C++" . "cpp") ("emacs-lisp" . "el") ("elisp" . "el"))
org-publish-timestamp-directory "/home/richard/.emacs.d/var/org/timestamps/"
org-export-before-parsing-hook '(org-attach-expand-links)
org-id-locations-file "/home/richard/.emacs.d/var/org/id-locations.el"
org-confirm-shell-link-function 'yes-or-no-p
org-link-parameters '(("attachment" :follow org-attach-follow :complete org-attach-complete-link) ("id" :follow org-id-open)
       ("eww" :follow org-eww-open :store org-eww-store-link) ("rmail" :follow org-rmail-open :store org-rmail-store-link)
       ("mhe" :follow org-mhe-open :store org-mhe-store-link)
       ("irc" :follow org-irc-visit :store org-irc-store-link :export org-irc-export)
       ("info" :follow org-info-open :export org-info-export :store org-info-store-link)
       ("gnus" :follow org-gnus-open :store org-gnus-store-link)
       ("docview" :follow org-docview-open :export org-docview-export :store org-docview-store-link)
       ("bibtex" :follow org-bibtex-open :store org-bibtex-store-link)
       ("bbdb" :follow org-bbdb-open :export org-bbdb-export :complete org-bbdb-complete-link :store org-bbdb-store-link)
       ("w3m" :store org-w3m-store-link) ("file+sys") ("file+emacs") ("shell" :follow org-link--open-shell)
       ("news" :follow #[514 "\301\300\302\x04Q\x02\"\207" ["news" browse-url ":"] 6 "\n\n(fn URL ARG)"])
       ("mailto" :follow #[514 "\301\300\302\x04Q\x02\"\207" ["mailto" browse-url ":"] 6 "\n\n(fn URL ARG)"])
       ("https" :follow #[514 "\301\300\302\x04Q\x02\"\207" ["https" browse-url ":"] 6 "\n\n(fn URL ARG)"])
       ("http" :follow #[514 "\301\300\302\x04Q\x02\"\207" ["http" browse-url ":"] 6 "\n\n(fn URL ARG)"])
       ("ftp" :follow #[514 "\301\300\302\x04Q\x02\"\207" ["ftp" browse-url ":"] 6 "\n\n(fn URL ARG)"])
       ("help" :follow org-link--open-help) ("file" :complete org-link-complete-file)
       ("elisp" :follow org-link--open-elisp) ("doi" :follow org-link--open-doi))
org-latex-format-headline-function 'org-latex-format-headline-default-function
org-latex-logfiles-extensions '("lof" "lot" "tex~" "aux" "idx" "log" "out" "toc" "nav" "snm" "vrb" "dvi" "fdb_latexmk" "blg" "brf" "fls"
"entoc" "ps" "spl" "bbl")
org-link-elisp-confirm-function 'yes-or-no-p
org-latex-format-inlinetask-function 'org-latex-format-inlinetask-default-function
org-html-format-drawer-function #[514 "\207" [] 3 "\n\n(fn NAME CONTENTS)"]
org-html-format-headline-function 'org-html-format-headline-default-function
org-confirm-babel-evaluate nil
org-fontify-whole-block-delimiter-line nil
)


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