Support space and backslash characters in runfile filenames.

Bazel supports them with bazelbuild/bazel#23331.

Step 2: support them for manifest-based runfiles.

elisp/runfiles/runfiles-test.el

@@ -54,8 +54,17 @@
                     "phst_rules_elisp/elisp/runfiles/test-manifest"))
          (runfiles (elisp/runfiles/make :manifest manifest
                                         :directory "/invalid/")))
-    (should (equal (elisp/runfiles/rlocation "testäα𝐴🐈'.txt" runfiles)
-                   "/:/runfiles/testäα𝐴🐈'.txt"))))
+    (pcase-dolist (`(,source ,target)
+                   '(("testäα𝐴🐈'.txt"
+                      "/:/runfiles/testäα𝐴🐈'.txt")
+                     ("target-with-space"
+                      "/:/runfiles/with space\\and backslash")
+                     ("target-with-newline"
+                      "/:/runfiles/with\nnewline\\and backslash")
+                     ("source with space,\nnewline,\\and backslash"
+                      "/:/runfiles/with space,\nnewline,\\and backslash")))
+      (ert-info (source :prefix "Source: ")
+        (should (equal (elisp/runfiles/rlocation source runfiles) target))))))
 
 (ert-deftest elisp/runfiles/make/empty-file ()
   (let* ((manifest (elisp/runfiles/rlocation

elisp/runfiles/runfiles.el

@@ -501,13 +501,31 @@ Return an object of type ‘elisp/runfiles/runfiles--manifest’."
       ;; Perform the same parsing as
       ;; https://github.com/bazelbuild/bazel/blob/6.4.0/tools/cpp/runfiles/runfiles_src.cc#L241.
       (while (not (eobp))
-        (pcase (buffer-substring-no-properties (point) (line-end-position))
-          ((rx bos (let key (+ (not (any ?\n ?\s))))
-               ?\s (let value (* nonl)) eos)
-           ;; Runfiles are always local, so quote them unconditionally.
-           (puthash key (if (string-empty-p value) :empty (concat "/:" value))
-                    manifest))
-          (other (signal 'elisp/runfiles/syntax-error (list filename other))))
+        (let ((line (buffer-substring-no-properties
+                     (point) (line-end-position)))
+              (escaped (eql (following-char) ?\s)))
+          (cl-flet* ((syntax-error ()
+                       (signal 'elisp/runfiles/syntax-error
+                               (list filename line)))
+                     (unescape (string &rest other)
+                       (let ((pairs `(,@other ("\\n" . "\n") ("\\b" . "\\"))))
+                         (replace-regexp-in-string
+                          (rx ?\\ (? anychar))
+                          (lambda (seq)
+                            (or (cdr (assoc seq pairs)) (syntax-error)))
+                          string :fixedcase :literal))))
+            (pcase (if escaped (substring-no-properties line 1) line)
+              ((rx bos (let key (+ (not (any ?\n ?\s))))
+                   ?\s (let value (* nonl)) eos)
+               (when escaped
+                 (cl-callf unescape key '("\\s" . " "))
+                 (cl-callf unescape value))
+               (puthash key
+                        ;; Runfiles are always local, so quote them
+                        ;; unconditionally.
+                        (if (string-empty-p value) :empty (concat "/:" value))
+                        manifest))
+              (_ (syntax-error)))))
         (forward-line)))
     (elisp/runfiles/manifest--make filename manifest)))
 

elisp/runfiles/test-manifest

@@ -1,3 +1,6 @@
 __init__.py 
 foo/bar runfiles/foo/bar
 testäα𝐴🐈'.txt /runfiles/testäα𝐴🐈'.txt
+target-with-space /runfiles/with space\and backslash
+ target-with-newline /runfiles/with\nnewline\band backslash
+ source\swith\sspace,\nnewline,\band\sbackslash /runfiles/with space,\nnewline,\band backslash