look past comments in a public form's header

semen.scm

@@ -204,21 +204,10 @@
             acc)))
 
 (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 (fn-header-length fn-form)))
-    ;; 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). Comments in the body are
+  ;; left in place as ordinary statements and preserved into the
+  ;; generated C.
+  (strip-header-comments fn-form (fn-header-length fn-form)))
 
 (define (process-fn sex-fn-raw acc)
   (let-values (((doc sex-fn)

sex-modules.scm

@@ -72,9 +72,10 @@
      (list)
      raw-forms)))
 
-(define (public-fn-interface form)
+(define (public-fn-interface raw-form)
   ;; (pub fn name args ret . body) -> prototype, keeping a docstring so
   ;; the importer can emit it above the declaration
+  (let ((form (strip-header-comments raw-form 5)))
     (match form
       (('pub 'fn name args ret)
        form)
@@ -83,7 +84,7 @@
       (('pub 'fn name args ret (? string? doc) . _)
        `(pub fn ,name ,args ,ret ,doc))
       (('pub 'fn name args ret . _)
-     `(pub fn ,name ,args ,ret))))
+       `(pub fn ,name ,args ,ret)))))
 
 ;;; TODO: use semen facilities to analyze modules
 (define (process-public-interface-form form acc)
@@ -92,8 +93,9 @@
     ;; with external linkage
     (('pub 'fn . _)
      (cons (copy-form-source! form (public-fn-interface form)) acc))
-    (('pub 'var name type . _)
-     (cons (copy-form-source! form `(extern var ,name ,type)) acc))
+    (('pub 'var . _)
+     (match-let ((('pub 'var name type . _) (strip-header-comments form 4)))
+       (cons (copy-form-source! form `(extern var ,name ,type)) acc)))
     (('pub (or 'define 'defmacro 'enum 'import 'include 'struct 'typedef 'union) . _)
      (cons (copy-form-source! form (cdr form)) acc))
     (('pub . _)

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
   "A greeting to print."
@@ -25,7 +29,8 @@
            (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
   "Print a greeting for NAME."
   (++ 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)