Improve support for Scheme R6RS and R7RS libraries (bug#54704)

* etc/NEWS (Scheme mode): Document improved file-type auto-detection
and Imenu support for R6RS and R7RS Scheme libraries.
* lisp/files.el (auto-mode-alist): Associate the '.sls' (R6RS Scheme
Library Source) and '.sld' (R7RS Scheme Library Definition) file name
extensions with the Scheme mode.
* lisp/progmodes/scheme.el (scheme-imenu-generic-expression): Make
Imenu recognize the members nested (and so indented) inside of
'library' (R6RS) or 'define-library' (R7RS) forms.

etc/NEWS

@@ -3055,6 +3055,19 @@ name.
 This key is now bound to 'Buffer-menu-view-other-window', which will
 view this line's buffer in View mode in another window.
 
+** Scheme mode
+
+---
+*** Auto-detection of Scheme library files.
+Emacs now automatically enables the Scheme mode when opening R6RS
+Scheme Library Source ('.sls') files and R7RS Scheme Library
+Definition ('.sld') files.
+
+---
+*** Imenu members for R6RS and R7RS library members.
+Imenu now lists the members directly nested in R6RS Scheme libraries
+('library') and R7RS libraries ('define-library').
+
 
 * New Modes and Packages in Emacs 29.1
 

lisp/files.el

@@ -2850,7 +2850,7 @@ since only a single case-insensitive search through the alist is made."
      ("\\.emacs-places\\'" . lisp-data-mode)
      ("\\.el\\'" . emacs-lisp-mode)
      ("Project\\.ede\\'" . emacs-lisp-mode)
-     ("\\.\\(scm\\|stk\\|ss\\|sch\\)\\'" . scheme-mode)
+     ("\\.\\(scm\\|sls\\|sld\\|stk\\|ss\\|sch\\)\\'" . scheme-mode)
      ("\\.l\\'" . lisp-mode)
      ("\\.li?sp\\'" . lisp-mode)
      ("\\.[fF]\\'" . fortran-mode)

lisp/progmodes/scheme.el

@@ -115,7 +115,8 @@
 
 (defvar scheme-imenu-generic-expression
   `((nil
-     ,(rx bol "(define"
+     ,(rx bol (zero-or-more space)
+          "(define"
           (zero-or-one "*")
           (zero-or-one "-public")
           (one-or-more space)
@@ -123,36 +124,41 @@
           (group (one-or-more (or word (syntax symbol)))))
      1)
     ("Methods"
-     ,(rx bol "(define-"
+     ,(rx bol (zero-or-more space)
+          "(define-"
           (or "generic" "method" "accessor")
           (one-or-more space)
           (zero-or-one "(")
           (group (one-or-more (or word (syntax symbol)))))
      1)
     ("Classes"
-     ,(rx bol "(define-class"
+     ,(rx bol (zero-or-more space)
+          "(define-class"
           (one-or-more space)
           (zero-or-one "(")
           (group (one-or-more (or word (syntax symbol)))))
      1)
     ("Records"
-     ,(rx bol "(define-record-type"
+     ,(rx bol (zero-or-more space)
+          "(define-record-type"
           (zero-or-one "*")
           (one-or-more space)
           (group (one-or-more (or word (syntax symbol)))))
      1)
     ("Conditions"
-     ,(rx bol "(define-condition-type"
+     ,(rx bol (zero-or-more space)
+          "(define-condition-type"
           (one-or-more space)
           (group (one-or-more (or word (syntax symbol)))))
      1)
     ("Modules"
-     ,(rx bol "(define-module"
+     ,(rx bol (zero-or-more space)
+          "(define-module"
           (one-or-more space)
           (group "(" (one-or-more any) ")"))
      1)
     ("Macros"
-     ,(rx bol "("
+     ,(rx bol (zero-or-more space) "("
           (or (and "defmacro"
                    (zero-or-one "*")
                    (zero-or-one "-public"))