look past comments in a public form's header

semen.scm

@@ -142,21 +142,9 @@
 ;;; Fn processing
 
 (define (strip-fn-header-comments fn-form)
-  ;; Remove comment forms from the function header
-  ;; ([pub|extern] fn name arglist rettype) so the positional accessors
-  ;; below are not shifted. Comments in the body are left in place as
-  ;; ordinary statements and preserved into the generated C.
-  (let ((header-count (if (memq (car fn-form) '(pub extern)) 5 4)))
-    ;; This always rebuilds the list, so the location has to be carried
-    ;; over explicitly -- otherwise every function loses it
-    (copy-form-source!
-     fn-form
-     (let loop ((form fn-form) (kept 0) (acc (list)))
-       (cond
-        ((null? form) (reverse acc))
-        ((= kept header-count) (append (reverse acc) form))
-        ((comment-form? (car form)) (loop (cdr form) kept acc))
-        (else (loop (cdr form) (+ kept 1) (cons (car form) acc))))))))
+  ;; ([pub|extern] fn name arglist rettype)
+  (strip-header-comments fn-form
+                         (if (memq (car fn-form) '(pub extern)) 5 4)))
 
 (define (process-fn sex-fn-raw acc)
   (let* ((sex-fn (strip-fn-header-comments sex-fn-raw))

sex-modules.scm

@@ -79,10 +79,16 @@
        ;; A function is reduced to a prototype and keeps its `pub', so
        ;; the importing unit declares it with external linkage
        ((fn)
-        (cons (copy-form-source! form (take form 5)) acc))
+        (cons (copy-form-source!
+               form
+               (take (strip-header-comments form 5) 5))
+              acc))
        ;; A variable becomes an `extern' declaration
        ((var)
-        (cons (copy-form-source! form (cons 'extern (take (cdr form) 3))) acc))
+        (cons (copy-form-source!
+               form
+               (cons 'extern (take (cdr (strip-header-comments form 4)) 3)))
+              acc))
        ((define defmacro enum import include struct typedef union)
         (cons (copy-form-source! form (cdr form)) acc))
        (else (sex-error form "pub must be followed by a definition" form))))

tests/modules/Makefile

@@ -11,6 +11,9 @@
 # It also checks what only a second translation unit can check: that an
 # imported type reaches the type database, by expanding a macro that
 # reads the imported struct's fields.
+#
+# The public forms carry comments in their headers, which the reduction
+# to a prototype and to an extern both have to look past.
 
 SEXC ?= ../../sexc
 

tests/modules/greet.sex

@@ -7,7 +7,11 @@
 
 (include stdio.h)
 
-(pub var greet-count int 0)
+(pub var greet-count ;; a comment in the header of a public form is
+                     ;; not part of it: what the importer is given has
+                     ;; to be `extern int greet-count', not a form
+                     ;; counted off by one
+  int 0)
 
 (pub struct greeting ((text (* const char)) (times int)))
 
@@ -23,7 +27,8 @@
            (lambda (name field-type)
              `(printf "%s " ,(symbol->string name))))))
 
-(pub fn greet ((name (* const char))) void
+(pub fn greet ;; ...and here the prototype would lose its return type
+  ((name (* const char))) void
   (++ greet-count)
   (printf "hello, %s\n" name))
 

tools/sextest/utils.module.scm

@@ -3,6 +3,7 @@
      set-working-directory
      to-absolute-pathname
      comment-form?
+     strip-header-comments
      list-split
      list-join
      recons

utils.module.scm

@@ -3,6 +3,7 @@
      set-working-directory
      to-absolute-pathname
      comment-form?
+     strip-header-comments
      list-split
      list-join
      recons

utils.scm

@@ -45,6 +45,21 @@
 (define (comment-form? form)
   (and (pair? form) (eq? (car form) 'comment)))
 
+;;; Remove the comment forms from the first COUNT elements of FORM --
+;;; its header -- so that the positional accessors reading it are not
+;;; shifted by one
+(define (strip-header-comments form count)
+  ;; This always rebuilds the list, so the location has to be carried
+  ;; over explicitly -- otherwise every form loses it
+  (copy-form-source!
+   form
+   (let loop ((rest form) (kept 0) (acc (list)))
+     (cond
+      ((null? rest) (reverse acc))
+      ((= kept count) (append (reverse acc) rest))
+      ((comment-form? (car rest)) (loop (cdr rest) kept acc))
+      (else (loop (cdr rest) (+ kept 1) (cons (car rest) acc)))))))
+
 (define (list-split src-list split-elt)
   ;; split '(1 2 / 3 4 / 5 6) by '/ -> '((1 2) (3 4) (5 6))
   (fold (lambda (elt acc)