Can't open a full file path from clipboard in a minibuffer with ivy when match is required (mml-attach-file)

[xuhdev]

If finding a file a match is required, I don't seem to be able to paste in a full path and accept the result, even if the file exists. This is not the case with the original completing-read-function (completing-read-default).

To reproduce, I use mml-attach-file.

1. Start Emacs with make plain.
2. M-x mml-attach-file.
3. Press //, copy an existing file path to the minibuffer. Remove the duplicate leading slashes. Make sure the file is in some subdirectory.
4. Push enter.

Minibuffer shows error: "Match required" and refuses to accept the input.

Rerun the steps with emacs -Q without ivy, the input is accepted.

In GNU Emacs 29.4 (build 1, x86_64-redhat-linux-gnu, GTK+ Version
 3.24.43, cairo version 1.18.0) of 2024-10-10 built on
 4825182c94fc4195b65c80c30f523a16
System Description: Fedora Linux 41 (Workstation Edition)

Configured using:
 'configure --build=x86_64-redhat-linux-gnu
 --host=x86_64-redhat-linux-gnu --program-prefix=
 --disable-dependency-tracking --prefix=/usr --exec-prefix=/usr
 --bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc
 --datadir=/usr/share --includedir=/usr/include --libdir=/usr/lib64
 --libexecdir=/usr/libexec --localstatedir=/var --runstatedir=/run
 --sharedstatedir=/var/lib --mandir=/usr/share/man
 --infodir=/usr/share/info --with-cairo --with-dbus --with-gif
 --with-gpm=no --with-harfbuzz --with-jpeg --with-json --with-modules
 --with-native-compilation=aot --with-pgtk --with-png --with-rsvg
 --with-sqlite3 --with-tiff --with-tree-sitter --with-webp --with-xpm
 build_alias=x86_64-redhat-linux-gnu host_alias=x86_64-redhat-linux-gnu
 CC=gcc 'CFLAGS=-DMAIL_USE_LOCKF -O2 -flto=auto -ffat-lto-objects
 -fexceptions -g -grecord-gcc-switches -pipe -Wall
 -Werror=format-security -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3
 -Wp,-D_GLIBCXX_ASSERTIONS
 -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong
 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -march=x86-64
 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection
 -fcf-protection -mtls-dialect=gnu2 -fno-omit-frame-pointer
 -mno-omit-leaf-frame-pointer ' 'LDFLAGS=-Wl,-z,relro -Wl,--as-needed
 -Wl,-z,pack-relative-relocs -Wl,-z,now
 -specs=/usr/lib/rpm/redhat/redhat-hardened-ld
 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -Wl,--build-id=sha1
 -specs=/usr/lib/rpm/redhat/redhat-package-notes '
 PKG_CONFIG_PATH=:/usr/lib64/pkgconfig:/usr/share/pkgconfig CXX=g++
 'CXXFLAGS=-O2 -flto=auto -ffat-lto-objects -fexceptions -g
 -grecord-gcc-switches -pipe -Wall -Werror=format-security
 -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS
 -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong
 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -march=x86-64
 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection
 -fcf-protection -mtls-dialect=gnu2 -fno-omit-frame-pointer
 -mno-omit-leaf-frame-pointer ''

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG JSON
LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY
PDUMPER PGTK PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF
TOOLKIT_SCROLL_BARS TREE_SITTER WEBP XIM GTK3 ZLIB

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  shell-dirtrack-mode: t
  counsel-mode: t
  ivy-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message yank-media puny rfc822 mml
mml-sec epa derived epg rfc6068 epg-config gnus-util mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail
rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils ffap tramp
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project dired dired-loaddefs compile text-property-search comint
ansi-osc ansi-color swiper cl-extra help-mode ivy delsel ring ivy-faces
ivy-overlay colir color finder-inf 0blayout-autoloads 0x0-autoloads
avy-autoloads hydra-autoloads lv-autoloads wgrep-autoloads package
browse-url url url-proxy url-privacy url-expand url-methods url-history
url-cookie generate-lisp-file url-domsuf url-util mailcap url-handlers
url-parse auth-source cl-seq eieio eieio-core cl-macs password-cache
json subr-x map byte-opt gv bytecomp byte-compile url-vars cl-loaddefs
cl-lib rmc iso-transl tooltip cconv eldoc paren electric uniquify
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pgtk-win term/common-win pgtk-dnd tool-bar dnd fontset image regexp-opt
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frame minibuffer nadvice seq simple cl-generic indonesian philippine
cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
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european ethiopic indian cyrillic chinese composite emoji-zwj charscript
charprop case-table epa-hook jka-cmpr-hook help abbrev obarray oclosure
cl-preloaded button loaddefs theme-loaddefs faces cus-face macroexp
files window text-properties overlay sha1 md5 base64 format env
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threads dbusbind inotify dynamic-setting system-font-setting
font-render-setting cairo gtk pgtk multi-tty make-network-process
native-compile emacs)