Allow custom completions to have leading dots

By default, fish does not complete files that have leading dots, unless the
wildcard itself has a leading dot. However this also affected completions;
for example `git add` would not offer `.gitlab-ci.yml` because it has a
leading dot.

Relax this for custom completions. Default file expansion still
suppresses leading dots, but now custom completions can create
leading-dot completions and they will be offered.

Fixes #3707.

(cherry picked from commit b7de768c73)

CHANGELOG.rst

@@ -49,6 +49,7 @@ Interactive improvements
 - A longstanding issue where items in the pager would sometimes display without proper formatting has been fixed (:issue:`9617`).
 - The :kbd:`Alt` +\ :kbd:`l` binding, which lists the directory of the token under the cursor, correctly expands tilde (``~``) to the home directory (:issue:`9954`).
 - Various fish utilities that use an external pager will now try a selection of common pagers if the :envvar:`PAGER` environment variable is not set, or write the output to the screen without a pager if there is not one available (:issue:`10074`)
+- Command-specific tab completions may now offer results whose first character is a period. For example, it is now possible to tab-complete ``git add`` for files with leading periods. The default file completions hide these files, unless the token itself has a leading period (:issue:`3707`).
 
 Improved prompts
 ^^^^^^^^^^^^^^^^

src/complete.cpp

@@ -366,7 +366,8 @@ class completer_t {
     bool conditions_test(const wcstring_list_t &conditions);
 
     void complete_strings(const wcstring &wc_escaped, const description_func_t &desc_func,
-                          const completion_list_t &possible_comp, complete_flags_t flags);
+                          const completion_list_t &possible_comp, complete_flags_t flags,
+                          expand_flags_t extra_expand_flags = {});
 
     expand_flags_t expand_flags() const {
         expand_flags_t result{};
@@ -510,12 +511,16 @@ static void parse_cmd_string(const wcstring &str, wcstring *path, wcstring *cmd,
 /// @param  possible_comp
 ///    the list of possible completions to iterate over
 /// @param  flags
-///    The flags
+///    The flags controlling completion
+/// @param extra_expand_flags
+///    Additional flags controlling expansion.
 void completer_t::complete_strings(const wcstring &wc_escaped, const description_func_t &desc_func,
-                                   const completion_list_t &possible_comp, complete_flags_t flags) {
+                                   const completion_list_t &possible_comp, complete_flags_t flags,
+                                   expand_flags_t extra_expand_flags) {
     wcstring tmp = wc_escaped;
     if (!expand_one(tmp,
-                    this->expand_flags() | expand_flag::skip_cmdsubst | expand_flag::skip_wildcards,
+                    this->expand_flags() | extra_expand_flags | expand_flag::skip_cmdsubst |
+                        expand_flag::skip_wildcards,
                     ctx))
         return;
 
@@ -525,7 +530,7 @@ void completer_t::complete_strings(const wcstring &wc_escaped, const description
         const wcstring &comp_str = comp.completion;
         if (!comp_str.empty()) {
             wildcard_complete(comp_str, wc.c_str(), desc_func, &this->completions,
-                              this->expand_flags(), flags);
+                              this->expand_flags() | extra_expand_flags, flags);
         }
     }
 }
@@ -730,7 +735,9 @@ void completer_t::complete_from_args(const wcstring &str, const wcstring &args,
         ctx.parser->set_last_statuses(status);
     }
 
-    this->complete_strings(escape_string(str), const_desc(desc), possible_comp, flags);
+    // Allow leading dots - see #3707.
+    this->complete_strings(escape_string(str), const_desc(desc), possible_comp, flags,
+                           expand_flag::allow_nonliteral_leading_dot);
 }
 
 static size_t leading_dash_count(const wchar_t *str) {

src/expand.h

@@ -45,6 +45,10 @@ enum class expand_flag {
     /// Disallow directory abbreviations like /u/l/b for /usr/local/bin. Only applicable if
     /// fuzzy_match is set.
     no_fuzzy_directories,
+    /// Allows matching a leading dot even if the wildcard does not contain one.
+    /// By default, wildcards only match a leading dot literally; this is why e.g. '*' does not
+    /// match hidden files.
+    allow_nonliteral_leading_dot,
     /// Do expansions specifically to support cd. This means using CDPATH as a list of potential
     /// working directories, and to use logical instead of physical paths.
     special_for_cd,

src/wildcard.cpp

@@ -191,7 +191,8 @@ static wildcard_result_t wildcard_complete_internal(const wchar_t *const str, si
 
     // Maybe early out for hidden files. We require that the wildcard match these exactly (i.e. a
     // dot); ANY_STRING not allowed.
-    if (is_first_call && str[0] == L'.' && wc[0] != L'.') {
+    if (is_first_call && !params.expand_flags.get(expand_flag::allow_nonliteral_leading_dot) &&
+        str[0] == L'.' && wc[0] != L'.') {
         return wildcard_result_t::no_match;
     }
 

tests/checks/complete.fish

@@ -531,6 +531,22 @@ begin
     # CHECK: Empty completions
 end
 
+rm -$f $tmpdir/*
+
+# Leading dots are not completed for default file completion,
+# but may be for custom command (e.g. git add).
+function dotty
+end
+function notty
+end
+complete -c dotty --no-files -a '(echo .a*)'
+touch .abc .def
+complete -C'notty '
+echo "Should be nothing"
+# CHECK: Should be nothing
+complete -C'dotty '
+# CHECK: .abc
+
 rm -r $tmpdir
 
 complete -C'complete --command=mktemp' | string replace -rf '=mktemp\t.*' '=mktemp'