Merge pull request #10208 from 9999years/print-strings-directly

`:print` strings directly in `nix repl`

(cherry picked from commit 3539172fd2f7cee639ce46423c58beca4231f2db)
Change-Id: I1972f3bf3b56312851f38288509d371d37f21677
Upstream-PR: https://github.com/NixOS/nix/pull/10208

src/libcmd/repl.cc

@@ -412,6 +412,7 @@ ProcessLineResult NixRepl::processLine(std::string line)
              << "  :l, :load <path>             Load Nix expression and add it to scope\n"
              << "  :lf, :load-flake <ref>       Load Nix flake and add it to scope\n"
              << "  :p, :print <expr>            Evaluate and print expression recursively\n"
+             << "                               Strings are printed directly, without escaping.\n"
              << "  :q, :quit                    Exit nix-repl\n"
              << "  :r, :reload                  Reload all files\n"
              << "  :sh <expr>                   Build dependencies of derivation, then start\n"
@@ -619,7 +620,11 @@ ProcessLineResult NixRepl::processLine(std::string line)
     else if (command == ":p" || command == ":print") {
         Value v;
         evalString(arg, v);
-        printValue(std::cout, v);
+        if (v.type() == nString) {
+            std::cout << v.string.s;
+        } else {
+            printValue(std::cout, v);
+        }
         std::cout << std::endl;
     }
 

tests/functional/repl_characterization/data/repl_printing.test

@@ -0,0 +1,92 @@
+Printing a string with escapes in it will render as a string normally.
+
+  nix-repl> "meow\n\nmeowmeowmeow"
+  "meow\n\nmeowmeowmeow"
+
+But with :p on the string itself it will print it literally to the output.
+
+  nix-repl> :p "meow\n\nmeowmeowmeow"
+  meow
+
+  meowmeowmeow
+
+  nix-repl> builtins.listToAttrs (builtins.genList (x: { name = "meow${toString x}"; value = { meow = { inherit x; s = "meowmeow\n\n${toString x}"; }; }; }) 10)
+  {
+    meow0 = { ... };
+    meow1 = { ... };
+    meow2 = { ... };
+    meow3 = { ... };
+    meow4 = { ... };
+    meow5 = { ... };
+    meow6 = { ... };
+    meow7 = { ... };
+    meow8 = { ... };
+    meow9 = { ... };
+  }
+
+Also, :p will expand attrs, but it will leave the strings escaped as normal if
+they aren't the top level item being printed.
+
+  nix-repl> :p builtins.listToAttrs (builtins.genList (x: { name = "meow${toString x}"; value = { meow = { inherit x; s = "meowmeow\n\n${toString x}"; }; }; }) 10)
+  {
+    meow0 = {
+      meow = {
+        s = "meowmeow\n\n0";
+        x = 0;
+      };
+    };
+    meow1 = {
+      meow = {
+        s = "meowmeow\n\n1";
+        x = 1;
+      };
+    };
+    meow2 = {
+      meow = {
+        s = "meowmeow\n\n2";
+        x = 2;
+      };
+    };
+    meow3 = {
+      meow = {
+        s = "meowmeow\n\n3";
+        x = 3;
+      };
+    };
+    meow4 = {
+      meow = {
+        s = "meowmeow\n\n4";
+        x = 4;
+      };
+    };
+    meow5 = {
+      meow = {
+        s = "meowmeow\n\n5";
+        x = 5;
+      };
+    };
+    meow6 = {
+      meow = {
+        s = "meowmeow\n\n6";
+        x = 6;
+      };
+    };
+    meow7 = {
+      meow = {
+        s = "meowmeow\n\n7";
+        x = 7;
+      };
+    };
+    meow8 = {
+      meow = {
+        s = "meowmeow\n\n8";
+        x = 8;
+      };
+    };
+    meow9 = {
+      meow = {
+        s = "meowmeow\n\n9";
+        x = 9;
+      };
+    };
+  }

tests/functional/repl_characterization/repl_characterization.cc

@@ -185,5 +185,6 @@ REPL_TEST(regression_9917);
 REPL_TEST(regression_9918);
 REPL_TEST(regression_l145);
 REPL_TEST(stack_vars);
+REPL_TEST(repl_printing);
 
 }; // namespace nix

tests/unit/libexpr-support/tests/libexpr.hh

@@ -71,7 +71,7 @@ namespace nix {
         if (arg.type() != nString) {
             return false;
         }
-        return std::string_view(arg.string.s) == s;
+        return std::string_view(arg.string.s) == std::string_view(s);
     }
 
     MATCHER_P(IsIntEq, v, fmt("The string is equal to \"%1%\"", v)) {
@@ -106,7 +106,7 @@ namespace nix {
             if (arg.type() != nPath) {
                 *result_listener << "Expected a path got " << arg.type();
                 return false;
-            } else if (std::string_view(arg.string.s) != p) {
+            } else if (std::string_view(arg._path) != p) {
                 *result_listener << "Expected a path that equals \"" << p << "\" but got: " << arg.string.s;
                 return false;
             }