Revert "StorePath: reject names starting with '.'"

This reverts commit 24bda0c7b381e1a017023c6f7cb9661fae8560bd.

(cherry picked from commit 9ddd0f2af8fd95e1380027a70d0aa650ea2fd5e4)
Change-Id: Ideb547e2a8ac911cf39d58d3e0c1553867bdd776

src/libstore/path-regex.hh

@@ -3,6 +3,6 @@
 
 namespace nix {
 
-static constexpr std::string_view nameRegexStr = R"([0-9a-zA-Z\+\-_\?=][0-9a-zA-Z\+\-\._\?=]*)";
+static constexpr std::string_view nameRegexStr = R"([0-9a-zA-Z\+\-\._\?=]+)";
 
 }

src/libstore/path.cc

@@ -11,8 +11,6 @@ static void checkName(std::string_view path, std::string_view name)
     if (name.size() > StorePath::MaxPathLen)
         throw BadStorePath("store path '%s' has a name longer than %d characters",
             path, StorePath::MaxPathLen);
-    if (name[0] == '.')
-        throw BadStorePath("store path '%s' starts with illegal character '.'", path);
     // See nameRegexStr for the definition
     for (auto c : name)
         if (!((c >= '0' && c <= '9')

tests/unit/libstore-support/tests/path.cc

@@ -47,13 +47,8 @@ Gen<StorePathName> Arbitrary<StorePathName>::arbitrary()
                 pre += '-';
                 break;
             case 64:
-                // names aren't permitted to start with a period,
-                // so just fall through to the next case here
-                if (c != 0) {
-                    pre += '.';
-                    break;
-                }
-                [[fallthrough]];
+                pre += '.';
+                break;
             case 65:
                 pre += '_';
                 break;

tests/unit/libstore/path.cc

@@ -39,7 +39,6 @@ TEST_DONT_PARSE(double_star, "**")
 TEST_DONT_PARSE(star_first, "*,foo")
 TEST_DONT_PARSE(star_second, "foo,*")
 TEST_DONT_PARSE(bang, "foo!o")
-TEST_DONT_PARSE(dotfile, ".gitignore")
 
 #undef TEST_DONT_PARSE