Add testcase for nix develop with __structuredAttrs

src/nix/develop.cc

@@ -256,6 +256,9 @@ struct Common : InstallableCommand, MixProfile
         // FIXME: properly unquote 'outputs'.
         StringMap rewrites;
         for (auto & outputName : tokenizeString<std::vector<std::string>>(replaceStrings(outputs->second.quoted, "'", ""))) {
+            // Hacky way to obtain the key of an associate array. This is needed for strctured attrs where
+            // `outputs` is an associative array. If the regex isn't matched, the non-structured-attrs behavior will
+            // be used.
             std::regex ptrn(R"re(\[([A-z0-9]+)\]=.*)re");
             std::smatch match;
             if (std::regex_match(outputName, match, ptrn)) {

src/nix/get-env.sh

@@ -8,6 +8,9 @@ if [[ -n $stdenv ]]; then
     source $stdenv/setup
 fi
 
+# In case of `__structuredAttrs = true;` the list of outputs is an associative
+# array with a format like `outname => /nix/store/hash-drvname-outname`, so `__olist`
+# must contain the array's keys (hence `${!...[@]}`) in this case.
 if [ -e .attrs.sh ]; then
     __olist="${!outputs[@]}"
 else
@@ -16,10 +19,10 @@ fi
 
 for __output in $__olist; do
     if [[ -z $__done ]]; then
-        export > ${!__output}
-        set >> ${!__output}
+        export > "${!__output}"
+        set >> "${!__output}"
         __done=1
     else
-        echo -n >> ${!__output}
+        echo -n >> "${!__output}"
     fi
 done