allow ^ in URLs

Users may select specific outputs using the ^output syntax or selecting
any output using ^*.

URL parsing currently doesn't support these kinds of output references:
parsing will fail.

Currently `queryRegex` was reused for URL fragments, which didn't
include support for ^. Now queryRegex has been split from fragmentRegex,
where only the fragmentRegex supports ^.

src/libexpr/flake/flakeref.cc

@@ -190,7 +190,7 @@ std::optional<std::pair<FlakeRef, std::string>> parseFlakeIdRef(
 
     static std::regex flakeRegex(
         "((" + flakeIdRegexS + ")(?:/(?:" + refAndOrRevRegex + "))?)"
-        + "(?:#(" + queryRegex + "))?",
+        + "(?:#(" + fragmentRegex + "))?",
         std::regex::ECMAScript);
 
     if (std::regex_match(url, match, flakeRegex)) {

src/libutil/tests/url-name.cc

@@ -10,6 +10,8 @@ namespace nix {
         ASSERT_EQ(getNameFromURL(parseURL("path:~/repos/nixpkgs#packages.x86_64-linux.hello")), "hello");
         ASSERT_EQ(getNameFromURL(parseURL("path:.#nonStandardAttr.mylaptop")), "nonStandardAttr.mylaptop");
         ASSERT_EQ(getNameFromURL(parseURL("path:./repos/myflake#nonStandardAttr.mylaptop")), "nonStandardAttr.mylaptop");
+        ASSERT_EQ(getNameFromURL(parseURL("path:./nixpkgs#packages.x86_64-linux.complex^bin,man")), "complex");
+        ASSERT_EQ(getNameFromURL(parseURL("path:./myproj#packages.x86_64-linux.default^*")), "myproj");
 
         ASSERT_EQ(getNameFromURL(parseURL("github:NixOS/nixpkgs#packages.x86_64-linux.hello")), "hello");
         ASSERT_EQ(getNameFromURL(parseURL("github:NixOS/nixpkgs#hello")), "hello");
@@ -60,5 +62,6 @@ namespace nix {
         ASSERT_EQ(getNameFromURL(parseURL("path:.")), std::nullopt);
         ASSERT_EQ(getNameFromURL(parseURL("file:.#")), std::nullopt);
         ASSERT_EQ(getNameFromURL(parseURL("path:.#packages.x86_64-linux.default")), std::nullopt);
+        ASSERT_EQ(getNameFromURL(parseURL("path:.#packages.x86_64-linux.default^*")), std::nullopt);
     }
 }

src/libutil/url-name.cc

@@ -5,12 +5,13 @@
 namespace nix {
 
 static const std::string attributeNamePattern("[a-z0-9_-]+");
-static const std::regex lastAttributeRegex("(?:" + attributeNamePattern + "\\.)*(?!default)(" + attributeNamePattern +")");
+static const std::regex lastAttributeRegex("(?:" + attributeNamePattern + "\\.)*(?!default)(" + attributeNamePattern +")(\\^.*)?");
 static const std::string pathSegmentPattern("[a-zA-Z0-9_-]+");
 static const std::regex lastPathSegmentRegex(".*/(" + pathSegmentPattern +")");
 static const std::regex secondPathSegmentRegex("(?:" + pathSegmentPattern + ")/(" + pathSegmentPattern +")(?:/.*)?");
 static const std::regex gitProviderRegex("github|gitlab|sourcehut");
 static const std::regex gitSchemeRegex("git($|\\+.*)");
+static const std::regex defaultOutputRegex(".*\\.default($|\\^.*)");
 
 std::optional<std::string> getNameFromURL(ParsedURL url) {
   std::smatch match;
@@ -32,7 +33,7 @@ std::optional<std::string> getNameFromURL(ParsedURL url) {
     return match.str(1);
 
   /* If everything failed but there is a non-default fragment, use it in full */
-  if (!url.fragment.empty() && !hasSuffix(url.fragment, "default"))
+  if (!url.fragment.empty() && !std::regex_match(url.fragment, defaultOutputRegex))
     return url.fragment;
 
   /* If there is no fragment, take the last element of the path */

src/libutil/url-parts.hh

@@ -19,6 +19,7 @@ const static std::string userRegex = "(?:(?:" + unreservedRegex + "|" + pctEncod
 const static std::string authorityRegex = "(?:" + userRegex + "@)?" + hostRegex + "(?::[0-9]+)?";
 const static std::string pcharRegex = "(?:" + unreservedRegex + "|" + pctEncoded + "|" + subdelimsRegex + "|[:@])";
 const static std::string queryRegex = "(?:" + pcharRegex + "|[/? \"])*";
+const static std::string fragmentRegex = "(?:" + pcharRegex + "|[/? \"^])*";
 const static std::string segmentRegex = "(?:" + pcharRegex + "*)";
 const static std::string absPathRegex = "(?:(?:/" + segmentRegex + ")*/?)";
 const static std::string pathRegex = "(?:" + segmentRegex + "(?:/" + segmentRegex + ")*/?)";

src/libutil/url.cc

@@ -15,7 +15,7 @@ ParsedURL parseURL(const std::string & url)
         "((" + schemeRegex + "):"
         + "(?:(?://(" + authorityRegex + ")(" + absPathRegex + "))|(/?" + pathRegex + ")))"
         + "(?:\\?(" + queryRegex + "))?"
-        + "(?:#(" + queryRegex + "))?",
+        + "(?:#(" + fragmentRegex + "))?",
         std::regex::ECMAScript);
 
     std::smatch match;

tests/functional/nix-profile.sh

@@ -126,6 +126,7 @@ nix profile install "$flake1Dir^*"
 [ -e $TEST_HOME/.nix-profile/include ]
 
 printf Nix > $flake1Dir/who
+nix profile list
 nix profile upgrade flake1
 [[ $($TEST_HOME/.nix-profile/bin/hello) = "Hello Nix" ]]
 [ -e $TEST_HOME/.nix-profile/share/man ]