diff --git a/pkgs/build-support/setup-hooks/autoreconf.sh b/pkgs/build-support/setup-hooks/autoreconf.sh
index 6ce879ac092de..763ea649c1c43 100644
--- a/pkgs/build-support/setup-hooks/autoreconf.sh
+++ b/pkgs/build-support/setup-hooks/autoreconf.sh
@@ -2,6 +2,11 @@ preConfigurePhases="${preConfigurePhases:-} autoreconfPhase"
 
 autoreconfPhase() {
     runHook preAutoreconf
-    autoreconf ${autoreconfFlags:---install --force --verbose}
+
+    local flagsArray=()
+    : "${autoreconfFlags:=--install --force --verbose}"
+    concatTo flagsArray autoreconfFlags
+
+    autoreconf "${flagsArray[@]}"
     runHook postAutoreconf
 }
diff --git a/pkgs/by-name/cm/cmake/setup-hook.sh b/pkgs/by-name/cm/cmake/setup-hook.sh
index 9ca4a6abeebc2..7ceb24227857d 100755
--- a/pkgs/by-name/cm/cmake/setup-hook.sh
+++ b/pkgs/by-name/cm/cmake/setup-hook.sh
@@ -38,7 +38,7 @@ cmakeConfigurePhase() {
     fi
 
     if [ -z "${dontAddPrefix-}" ]; then
-        cmakeFlags="-DCMAKE_INSTALL_PREFIX=$prefix $cmakeFlags"
+        prependToVar cmakeFlags "-DCMAKE_INSTALL_PREFIX=$prefix"
     fi
 
     # We should set the proper `CMAKE_SYSTEM_NAME`.
@@ -47,21 +47,21 @@ cmakeConfigurePhase() {
     # Unfortunately cmake seems to expect absolute paths for ar, ranlib, and
     # strip. Otherwise they are taken to be relative to the source root of the
     # package being built.
-    cmakeFlags="-DCMAKE_CXX_COMPILER=$CXX $cmakeFlags"
-    cmakeFlags="-DCMAKE_C_COMPILER=$CC $cmakeFlags"
-    cmakeFlags="-DCMAKE_AR=$(command -v $AR) $cmakeFlags"
-    cmakeFlags="-DCMAKE_RANLIB=$(command -v $RANLIB) $cmakeFlags"
-    cmakeFlags="-DCMAKE_STRIP=$(command -v $STRIP) $cmakeFlags"
+    prependToVar cmakeFlags "-DCMAKE_CXX_COMPILER=$CXX"
+    prependToVar cmakeFlags "-DCMAKE_C_COMPILER=$CC"
+    prependToVar cmakeFlags "-DCMAKE_AR=$(command -v $AR)"
+    prependToVar cmakeFlags "-DCMAKE_RANLIB=$(command -v $RANLIB)"
+    prependToVar cmakeFlags "-DCMAKE_STRIP=$(command -v $STRIP)"
 
     # on macOS we want to prefer Unix-style headers to Frameworks
     # because we usually do not package the framework
-    cmakeFlags="-DCMAKE_FIND_FRAMEWORK=LAST $cmakeFlags"
+    prependToVar cmakeFlags "-DCMAKE_FIND_FRAMEWORK=LAST"
 
     # we never want to use the global macOS SDK
-    cmakeFlags="-DCMAKE_OSX_SYSROOT= $cmakeFlags"
+    prependToVar cmakeFlags "-DCMAKE_OSX_SYSROOT="
 
     # correctly detect our clang compiler
-    cmakeFlags="-DCMAKE_POLICY_DEFAULT_CMP0025=NEW $cmakeFlags"
+    prependToVar cmakeFlags "-DCMAKE_POLICY_DEFAULT_CMP0025=NEW"
 
     # This installs shared libraries with a fully-specified install
     # name. By default, cmake installs shared libraries with just the
@@ -70,7 +70,7 @@ cmakeConfigurePhase() {
     # libraries are in a system path or in the same directory as the
     # executable. This flag makes the shared library accessible from its
     # nix/store directory.
-    cmakeFlags="-DCMAKE_INSTALL_NAME_DIR=${!outputLib}/lib $cmakeFlags"
+    prependToVar cmakeFlags "-DCMAKE_INSTALL_NAME_DIR=${!outputLib}/lib"
 
     # The docdir flag needs to include PROJECT_NAME as per GNU guidelines,
     # try to extract it from CMakeLists.txt.
@@ -93,39 +93,42 @@ cmakeConfigurePhase() {
     # This ensures correct paths with multiple output derivations
     # It requires the project to use variables from GNUInstallDirs module
     # https://cmake.org/cmake/help/latest/module/GNUInstallDirs.html
-    cmakeFlags="-DCMAKE_INSTALL_BINDIR=${!outputBin}/bin $cmakeFlags"
-    cmakeFlags="-DCMAKE_INSTALL_SBINDIR=${!outputBin}/sbin $cmakeFlags"
-    cmakeFlags="-DCMAKE_INSTALL_INCLUDEDIR=${!outputInclude}/include $cmakeFlags"
-    cmakeFlags="-DCMAKE_INSTALL_OLDINCLUDEDIR=${!outputInclude}/include $cmakeFlags"
-    cmakeFlags="-DCMAKE_INSTALL_MANDIR=${!outputMan}/share/man $cmakeFlags"
-    cmakeFlags="-DCMAKE_INSTALL_INFODIR=${!outputInfo}/share/info $cmakeFlags"
-    cmakeFlags="-DCMAKE_INSTALL_DOCDIR=${!outputDoc}/share/doc/${shareDocName} $cmakeFlags"
-    cmakeFlags="-DCMAKE_INSTALL_LIBDIR=${!outputLib}/lib $cmakeFlags"
-    cmakeFlags="-DCMAKE_INSTALL_LIBEXECDIR=${!outputLib}/libexec $cmakeFlags"
-    cmakeFlags="-DCMAKE_INSTALL_LOCALEDIR=${!outputLib}/share/locale $cmakeFlags"
+    prependToVar cmakeFlags "-DCMAKE_INSTALL_BINDIR=${!outputBin}/bin"
+    prependToVar cmakeFlags "-DCMAKE_INSTALL_SBINDIR=${!outputBin}/sbin"
+    prependToVar cmakeFlags "-DCMAKE_INSTALL_INCLUDEDIR=${!outputInclude}/include"
+    prependToVar cmakeFlags "-DCMAKE_INSTALL_OLDINCLUDEDIR=${!outputInclude}/include"
+    prependToVar cmakeFlags "-DCMAKE_INSTALL_MANDIR=${!outputMan}/share/man"
+    prependToVar cmakeFlags "-DCMAKE_INSTALL_INFODIR=${!outputInfo}/share/info"
+    prependToVar cmakeFlags "-DCMAKE_INSTALL_DOCDIR=${!outputDoc}/share/doc/${shareDocName}"
+    prependToVar cmakeFlags "-DCMAKE_INSTALL_LIBDIR=${!outputLib}/lib"
+    prependToVar cmakeFlags "-DCMAKE_INSTALL_LIBEXECDIR=${!outputLib}/libexec"
+    prependToVar cmakeFlags "-DCMAKE_INSTALL_LOCALEDIR=${!outputLib}/share/locale"
 
     # Don’t build tests when doCheck = false
     if [ -z "${doCheck-}" ]; then
-        cmakeFlags="-DBUILD_TESTING=OFF $cmakeFlags"
+        prependToVar cmakeFlags "-DBUILD_TESTING=OFF"
     fi
 
     # Always build Release, to ensure optimisation flags
-    cmakeFlags="-DCMAKE_BUILD_TYPE=${cmakeBuildType:-Release} $cmakeFlags"
+    prependToVar cmakeFlags "-DCMAKE_BUILD_TYPE=${cmakeBuildType:-Release}"
 
     # Disable user package registry to avoid potential side effects
     # and unecessary attempts to access non-existent home folder
     # https://cmake.org/cmake/help/latest/manual/cmake-packages.7.html#disabling-the-package-registry
-    cmakeFlags="-DCMAKE_EXPORT_NO_PACKAGE_REGISTRY=ON $cmakeFlags"
-    cmakeFlags="-DCMAKE_FIND_USE_PACKAGE_REGISTRY=OFF $cmakeFlags"
-    cmakeFlags="-DCMAKE_FIND_USE_SYSTEM_PACKAGE_REGISTRY=OFF $cmakeFlags"
+    prependToVar cmakeFlags "-DCMAKE_EXPORT_NO_PACKAGE_REGISTRY=ON"
+    prependToVar cmakeFlags "-DCMAKE_FIND_USE_PACKAGE_REGISTRY=OFF"
+    prependToVar cmakeFlags "-DCMAKE_FIND_USE_SYSTEM_PACKAGE_REGISTRY=OFF"
 
     if [ "${buildPhase-}" = ninjaBuildPhase ]; then
-        cmakeFlags="-GNinja $cmakeFlags"
+        prependToVar cmakeFlags "-GNinja"
     fi
 
-    echo "cmake flags: $cmakeFlags ${cmakeFlagsArray[@]}"
+    local flagsArray=()
+    concatTo flagsArray cmakeFlags cmakeFlagsArray
 
-    cmake "$cmakeDir" $cmakeFlags "${cmakeFlagsArray[@]}"
+    echoCmd 'cmake flags' "${flagsArray[@]}"
+
+    cmake "$cmakeDir" "${flagsArray[@]}"
 
     if ! [[ -v enableParallelBuilding ]]; then
         enableParallelBuilding=1
diff --git a/pkgs/by-name/lo/local-ai/package.nix b/pkgs/by-name/lo/local-ai/package.nix
index 4dbbd05fde29d..cf1ef1cc6b203 100644
--- a/pkgs/by-name/lo/local-ai/package.nix
+++ b/pkgs/by-name/lo/local-ai/package.nix
@@ -488,7 +488,7 @@ let
         ''${enableParallelBuilding:+-j''${NIX_BUILD_CORES}}
         SHELL=$SHELL
       )
-      _accumFlagsArray makeFlags makeFlagsArray buildFlags buildFlagsArray
+      concatTo flagsArray makeFlags makeFlagsArray buildFlags buildFlagsArray
       echoCmd 'build flags' "''${flagsArray[@]}"
       make build "''${flagsArray[@]}"
       unset flagsArray
diff --git a/pkgs/by-name/me/meson/setup-hook.sh b/pkgs/by-name/me/meson/setup-hook.sh
index 8266645452277..55ea8b5c1d973 100644
--- a/pkgs/by-name/me/meson/setup-hook.sh
+++ b/pkgs/by-name/me/meson/setup-hook.sh
@@ -21,11 +21,10 @@ mesonConfigurePhase() {
         "--localedir=${!outputLib}/share/locale"
         "-Dauto_features=${mesonAutoFeatures:-enabled}"
         "-Dwrap_mode=${mesonWrapMode:-nodownload}"
-        ${crossMesonFlags}
         "--buildtype=${mesonBuildType:-plain}"
     )
 
-    _accumFlagsArray mesonFlags mesonFlagsArray
+    concatTo flagsArray mesonFlags mesonFlagsArray
 
     echoCmd 'mesonConfigurePhase flags' "${flagsArray[@]}"
 
@@ -50,7 +49,8 @@ mesonConfigurePhase() {
 mesonCheckPhase() {
     runHook preCheck
 
-    local flagsArray=($mesonCheckFlags "${mesonCheckFlagsArray[@]}")
+    local flagsArray=()
+    concatTo flagsArray mesonCheckFlags mesonCheckFlagsArray
 
     echoCmd 'mesonCheckPhase flags' "${flagsArray[@]}"
     meson test --no-rebuild --print-errorlogs "${flagsArray[@]}"
@@ -64,12 +64,9 @@ mesonInstallPhase() {
     local flagsArray=()
 
     if [[ -n "$mesonInstallTags" ]]; then
-        flagsArray+=("--tags" "${mesonInstallTags// /,}")
+        flagsArray+=("--tags" "$(concatStringsSep "," mesonInstallTags)")
     fi
-    flagsArray+=(
-        $mesonInstallFlags
-        "${mesonInstallFlagsArray[@]}"
-    )
+    concatTo flagsArray mesonInstallFlags mesonInstallFlagsArray
 
     echoCmd 'mesonInstallPhase flags' "${flagsArray[@]}"
     meson install --no-rebuild "${flagsArray[@]}"
diff --git a/pkgs/by-name/ni/ninja/setup-hook.sh b/pkgs/by-name/ni/ninja/setup-hook.sh
index 7fa5e4675f39b..4f3bc5b5acfa4 100644
--- a/pkgs/by-name/ni/ninja/setup-hook.sh
+++ b/pkgs/by-name/ni/ninja/setup-hook.sh
@@ -1,3 +1,5 @@
+# shellcheck shell=bash
+
 ninjaBuildPhase() {
     runHook preBuild
 
@@ -9,9 +11,9 @@ ninjaBuildPhase() {
     fi
 
     local flagsArray=(
-        -j$buildCores
-        $ninjaFlags "${ninjaFlagsArray[@]}"
+        "-j$buildCores"
     )
+    concatTo flagsArray ninjaFlags ninjaFlagsArray
 
     echoCmd 'build flags' "${flagsArray[@]}"
     TERM=dumb ninja "${flagsArray[@]}"
@@ -24,7 +26,7 @@ ninjaCheckPhase() {
 
     if [ -z "${checkTarget:-}" ]; then
         if ninja -t query test >/dev/null 2>&1; then
-            checkTarget=test
+            checkTarget="test"
         fi
     fi
 
@@ -38,10 +40,9 @@ ninjaCheckPhase() {
         fi
 
         local flagsArray=(
-            -j$buildCores
-            $ninjaFlags "${ninjaFlagsArray[@]}"
-            $checkTarget
+            "-j$buildCores"
         )
+        concatTo flagsArray ninjaFlags ninjaFlagsArray checkTarget
 
         echoCmd 'check flags' "${flagsArray[@]}"
         TERM=dumb ninja "${flagsArray[@]}"
@@ -62,10 +63,10 @@ ninjaInstallPhase() {
 
     # shellcheck disable=SC2086
     local flagsArray=(
-        -j$buildCores
-        $ninjaFlags "${ninjaFlagsArray[@]}"
-        ${installTargets:-install}
+        "-j$buildCores"
     )
+    : "${installTargets:=install}"
+    concatTo flagsArray ninjaFlags ninjaFlagsArray installTargets
 
     echoCmd 'install flags' "${flagsArray[@]}"
     TERM=dumb ninja "${flagsArray[@]}"
@@ -73,14 +74,14 @@ ninjaInstallPhase() {
     runHook postInstall
 }
 
-if [ -z "${dontUseNinjaBuild-}" -a -z "${buildPhase-}" ]; then
+if [ -z "${dontUseNinjaBuild-}" ] && [ -z "${buildPhase-}" ]; then
     buildPhase=ninjaBuildPhase
 fi
 
-if [ -z "${dontUseNinjaCheck-}" -a -z "${checkPhase-}" ]; then
+if [ -z "${dontUseNinjaCheck-}" ] && [ -z "${checkPhase-}" ]; then
     checkPhase=ninjaCheckPhase
 fi
 
-if [ -z "${dontUseNinjaInstall-}" -a -z "${installPhase-}" ]; then
+if [ -z "${dontUseNinjaInstall-}" ] && [ -z "${installPhase-}" ]; then
     installPhase=ninjaInstallPhase
 fi
diff --git a/pkgs/stdenv/generic/setup.sh b/pkgs/stdenv/generic/setup.sh
index fc748aa12a665..ea61ec7509ce6 100644
--- a/pkgs/stdenv/generic/setup.sh
+++ b/pkgs/stdenv/generic/setup.sh
@@ -330,16 +330,16 @@ prependToVar() {
     fi
 
     # check if variable already exist and if it does then do extra checks
-    if declare -p "$1" 2> /dev/null | grep -q '^'; then
-        type="$(declare -p "$1")"
-        if [[ "$type" =~ "declare -A" ]]; then
-            echo "prependToVar(): ERROR: trying to use prependToVar on an associative array." >&2
-            return 1
-        elif [[ "$type" =~ "declare -a" ]]; then
-            useArray=true
-        else
-            useArray=false
-        fi
+    if type=$(declare -p "$1" 2> /dev/null); then
+        case "${type#* }" in
+            -A*)
+                echo "prependToVar(): ERROR: trying to use prependToVar on an associative array." >&2
+                return 1 ;;
+            -a*)
+                useArray=true ;;
+            *)
+                useArray=false ;;
+        esac
     fi
 
     shift
@@ -363,16 +363,16 @@ appendToVar() {
     fi
 
     # check if variable already exist and if it does then do extra checks
-    if declare -p "$1" 2> /dev/null | grep -q '^'; then
-        type="$(declare -p "$1")"
-        if [[ "$type" =~ "declare -A" ]]; then
-            echo "appendToVar(): ERROR: trying to use appendToVar on an associative array, use variable+=([\"X\"]=\"Y\") instead." >&2
-            return 1
-        elif [[ "$type" =~ "declare -a" ]]; then
-            useArray=true
-        else
-            useArray=false
-        fi
+    if type=$(declare -p "$1" 2> /dev/null); then
+        case "${type#* }" in
+            -A*)
+                echo "appendToVar(): ERROR: trying to use appendToVar on an associative array, use variable+=([\"X\"]=\"Y\") instead." >&2
+                return 1 ;;
+            -a*)
+                useArray=true ;;
+            *)
+                useArray=false ;;
+        esac
     fi
 
     shift
@@ -384,36 +384,57 @@ appendToVar() {
     fi
 }
 
-# Accumulate into `flagsArray` the flags from the named variables.
+# Accumulate flags from the named variables $2+ into the indexed array $1.
 #
-# If __structuredAttrs, the variables are all treated as arrays
-# and simply concatenated onto `flagsArray`.
-#
-# If not __structuredAttrs, then:
-#   * Each variable is treated as a string, and split on whitespace;
-#   * except variables whose names end in "Array", which are treated
-#     as arrays.
-_accumFlagsArray() {
-    local name
-    if [ -n "$__structuredAttrs" ]; then
-        for name in "$@"; do
-            local -n nameref="$name"
-            flagsArray+=( ${nameref+"${nameref[@]}"} )
-        done
-    else
-        for name in "$@"; do
+# Arrays are simply concatenated, strings are split on whitespace.
+concatTo() {
+    local -n targetref="$1"; shift
+    local name type
+    for name in "$@"; do
+        if type=$(declare -p "$name" 2> /dev/null); then
             local -n nameref="$name"
-            case "$name" in
-                *Array)
-                    # shellcheck disable=SC2206
-                    flagsArray+=( ${nameref+"${nameref[@]}"} ) ;;
+            case "${type#* }" in
+                -A*)
+                    echo "concatTo(): ERROR: trying to use concatTo on an associative array." >&2
+                    return 1 ;;
+                -a*)
+                    targetref+=( "${nameref[@]}" ) ;;
                 *)
                     # shellcheck disable=SC2206
-                    flagsArray+=( ${nameref-} ) ;;
+                    targetref+=( ${nameref-} ) ;;
             esac
-        done
-    fi
+        fi
+    done
+}
 
+# Concatenate a list of strings ($2) with a separator ($1) between each element.
+# The list can be an indexed array of strings or a single string. A single string
+# is split on spaces and then concatenated with the separator.
+#
+# $ flags="lorem ipsum dolor sit amet"
+# $ concatStringsSep ";" flags
+# lorem;ipsum;dolor;sit;amet
+#
+# $ flags=("lorem ipsum" "dolor" "sit amet")
+# $ concatStringsSep ";" flags
+# lorem ipsum;dolor;sit amet
+concatStringsSep() {
+    local sep="$1"
+    local name="$2"
+    local type oldifs
+    if type=$(declare -p "$name" 2> /dev/null); then
+        local -n nameref="$name"
+        case "${type#* }" in
+            -A*)
+                echo "concatStringsSep(): ERROR: trying to use concatStringsSep on an associative array." >&2
+                return 1 ;;
+            -a*)
+                local IFS="$sep"
+                echo -n "${nameref[*]}" ;;
+            *)
+                echo -n "${nameref// /"${sep}"}" ;;
+        esac
+    fi
 }
 
 # Add $1/lib* into rpaths.
@@ -1220,12 +1241,7 @@ unpackPhase() {
     fi
 
     local -a srcsArray
-    if [ -n "$__structuredAttrs" ]; then
-        srcsArray=( "${srcs[@]}" )
-    else
-        # shellcheck disable=SC2206
-        srcsArray=( $srcs )
-    fi
+    concatTo srcsArray srcs
 
     # To determine the source directory created by unpacking the
     # source archives, we record the contents of the current
@@ -1290,13 +1306,7 @@ patchPhase() {
     runHook prePatch
 
     local -a patchesArray
-    if [ -n "$__structuredAttrs" ]; then
-        # shellcheck disable=SC2206
-        patchesArray=( ${patches:+"${patches[@]}"} )
-    else
-        # shellcheck disable=SC2206
-        patchesArray=( ${patches:-} )
-    fi
+    concatTo patchesArray patches
 
     for i in "${patchesArray[@]}"; do
         echo "applying patch $i"
@@ -1317,12 +1327,8 @@ patchPhase() {
         esac
 
         local -a flagsArray
-        if [ -n "$__structuredAttrs" ]; then
-            flagsArray=( "${patchFlags[@]:--p1}" )
-        else
-            # shellcheck disable=SC2086,SC2206
-            flagsArray=( ${patchFlags:--p1} )
-        fi
+        : "${patchFlags:=-p1}"
+        concatTo flagsArray patchFlags
         # "2>&1" is a hack to make patch fail if the decompressor fails (nonexistent patch, etc.)
         # shellcheck disable=SC2086
         $uncompress < "$i" 2>&1 | patch "${flagsArray[@]}"
@@ -1408,7 +1414,7 @@ configurePhase() {
 
     if [ -n "$configureScript" ]; then
         local -a flagsArray
-        _accumFlagsArray configureFlags configureFlagsArray
+        concatTo flagsArray configureFlags configureFlagsArray
 
         echoCmd 'configure flags' "${flagsArray[@]}"
         # shellcheck disable=SC2086
@@ -1435,7 +1441,7 @@ buildPhase() {
             ${enableParallelBuilding:+-j${NIX_BUILD_CORES}}
             SHELL="$SHELL"
         )
-        _accumFlagsArray makeFlags makeFlagsArray buildFlags buildFlagsArray
+        concatTo flagsArray makeFlags makeFlagsArray buildFlags buildFlagsArray
 
         echoCmd 'build flags' "${flagsArray[@]}"
         make ${makefile:+-f $makefile} "${flagsArray[@]}"
@@ -1474,16 +1480,8 @@ checkPhase() {
             SHELL="$SHELL"
         )
 
-        _accumFlagsArray makeFlags makeFlagsArray
-        if [ -n "$__structuredAttrs" ]; then
-            flagsArray+=( "${checkFlags[@]:-VERBOSE=y}" )
-        else
-            # shellcheck disable=SC2206
-            flagsArray+=( ${checkFlags:-VERBOSE=y} )
-        fi
-        _accumFlagsArray checkFlagsArray
-        # shellcheck disable=SC2206
-        flagsArray+=( ${checkTarget} )
+        : "${checkFlags:=VERBOSE=y}"
+        concatTo flagsArray makeFlags makeFlagsArray checkFlags checkFlagsArray checkTarget
 
         echoCmd 'check flags' "${flagsArray[@]}"
         make ${makefile:+-f $makefile} "${flagsArray[@]}"
@@ -1516,13 +1514,9 @@ installPhase() {
         ${enableParallelInstalling:+-j${NIX_BUILD_CORES}}
         SHELL="$SHELL"
     )
-    _accumFlagsArray makeFlags makeFlagsArray installFlags installFlagsArray
-    if [ -n "$__structuredAttrs" ]; then
-        flagsArray+=( "${installTargets[@]:-install}" )
-    else
-        # shellcheck disable=SC2206
-        flagsArray+=( ${installTargets:-install} )
-    fi
+
+    : "${installTargets:=install}"
+    concatTo flagsArray makeFlags makeFlagsArray installFlags installFlagsArray installTargets
 
     echoCmd 'install flags' "${flagsArray[@]}"
     make ${makefile:+-f $makefile} "${flagsArray[@]}"
@@ -1605,10 +1599,9 @@ installCheckPhase() {
             SHELL="$SHELL"
         )
 
-        _accumFlagsArray makeFlags makeFlagsArray \
-          installCheckFlags installCheckFlagsArray
-        # shellcheck disable=SC2206
-        flagsArray+=( ${installCheckTarget:-installcheck} )
+        : "${installCheckTarget:=installcheck}"
+        concatTo flagsArray makeFlags makeFlagsArray \
+          installCheckFlags installCheckFlagsArray installCheckTarget
 
         echoCmd 'installcheck flags' "${flagsArray[@]}"
         make ${makefile:+-f $makefile} "${flagsArray[@]}"
@@ -1623,9 +1616,8 @@ distPhase() {
     runHook preDist
 
     local flagsArray=()
-    _accumFlagsArray distFlags distFlagsArray
-    # shellcheck disable=SC2206
-    flagsArray+=( ${distTarget:-dist} )
+    : "${distTarget:=dist}"
+    concatTo flagsArray distFlags distFlagsArray distTarget
 
     echo 'dist flags: %q' "${flagsArray[@]}"
     make ${makefile:+-f $makefile} "${flagsArray[@]}"
diff --git a/pkgs/test/stdenv/default.nix b/pkgs/test/stdenv/default.nix
index 00f1ce90ef3ad..a5b571b5a9f43 100644
--- a/pkgs/test/stdenv/default.nix
+++ b/pkgs/test/stdenv/default.nix
@@ -74,19 +74,19 @@ let
           declare -p string
 
           declare -A associativeArray=(["X"]="Y")
-          [[ $(appendToVar associativeArray "fail" 2>&1) =~ "trying to use" ]] || (echo "prependToVar did not catch prepending associativeArray" && false)
-          [[ $(prependToVar associativeArray "fail" 2>&1) =~ "trying to use" ]] || (echo "prependToVar did not catch prepending associativeArray" && false)
+          [[ $(appendToVar associativeArray "fail" 2>&1) =~ "trying to use" ]] || (echo "appendToVar did not throw appending to associativeArray" && false)
+          [[ $(prependToVar associativeArray "fail" 2>&1) =~ "trying to use" ]] || (echo "prependToVar did not throw prepending associativeArray" && false)
 
           [[ $string == "world testing-string hello" ]] || (echo "'\$string' was not 'world testing-string hello'" && false)
 
           # test appending to a unset variable
           appendToVar nonExistant created hello
-          typeset -p nonExistant
+          declare -p nonExistant
           if [[ -n $__structuredAttrs ]]; then
             [[ "''${nonExistant[@]}" == "created hello" ]]
           else
             # there's a extra " " in front here and a extra " " in the end of prependToVar
-            # shouldn't matter because these functions will mostly be used for $*Flags and the Flag variable will in most cases already exit
+            # shouldn't matter because these functions will mostly be used for $*Flags and the Flag variable will in most cases already exist
             [[ "$nonExistant" == " created hello" ]]
           fi
 
@@ -96,6 +96,65 @@ let
         '';
       } // extraAttrs);
 
+  testConcatTo = { name, stdenv', extraAttrs ? { } }:
+    stdenv'.mkDerivation
+      ({
+        inherit name;
+
+        string = "a b";
+        list = ["c" "d"];
+
+        passAsFile = [ "buildCommand" ] ++ lib.optionals (extraAttrs ? extraTest) [ "extraTest" ];
+        buildCommand = ''
+          declare -A associativeArray=(["X"]="Y")
+          [[ $(concatTo nowhere associativeArray 2>&1) =~ "trying to use" ]] || (echo "concatTo did not throw concatenating associativeArray" && false)
+
+          declare -a flagsArray
+          concatTo flagsArray string list
+          declare -p flagsArray
+          [[ "''${flagsArray[0]}" == "a" ]] || (echo "'\$flagsArray[0]' was not 'a'" && false)
+          [[ "''${flagsArray[1]}" == "b" ]] || (echo "'\$flagsArray[1]' was not 'b'" && false)
+          [[ "''${flagsArray[2]}" == "c" ]] || (echo "'\$flagsArray[2]' was not 'c'" && false)
+          [[ "''${flagsArray[3]}" == "d" ]] || (echo "'\$flagsArray[3]' was not 'd'" && false)
+
+          # test concatenating to unset variable
+          concatTo nonExistant string list
+          declare -p nonExistant
+          [[ "''${nonExistant[0]}" == "a" ]] || (echo "'\$nonExistant[0]' was not 'a'" && false)
+          [[ "''${nonExistant[1]}" == "b" ]] || (echo "'\$nonExistant[1]' was not 'b'" && false)
+          [[ "''${nonExistant[2]}" == "c" ]] || (echo "'\$nonExistant[2]' was not 'c'" && false)
+          [[ "''${nonExistant[3]}" == "d" ]] || (echo "'\$nonExistant[3]' was not 'd'" && false)
+
+          eval "$extraTest"
+
+          touch $out
+        '';
+      } // extraAttrs);
+
+  testConcatStringsSep = { name, stdenv' }:
+    stdenv'.mkDerivation
+      {
+        inherit name;
+
+        # NOTE: Testing with "&" as separator is intentional, because unquoted
+        # "&" has a special meaning in the "${var//pattern/replacement}" syntax.
+        # Cf. https://github.com/NixOS/nixpkgs/pull/318614#discussion_r1706191919
+        passAsFile = [ "buildCommand" ];
+        buildCommand = ''
+          declare -A associativeArray=(["X"]="Y")
+          [[ $(concatStringsSep ";" associativeArray 2>&1) =~ "trying to use" ]] || (echo "concatStringsSep did not throw concatenating associativeArray" && false)
+
+          string="lorem ipsum dolor sit amet"
+          stringWithSep="$(concatStringsSep "&" string)"
+          [[ "$stringWithSep" == "lorem&ipsum&dolor&sit&amet" ]] || (echo "'\$stringWithSep' was not 'lorem&ipsum&dolor&sit&amet'" && false)
+
+          array=("lorem ipsum" "dolor" "sit amet")
+          arrayWithSep="$(concatStringsSep "&" array)"
+          [[ "$arrayWithSep" == "lorem ipsum&dolor&sit amet" ]] || (echo "'\$arrayWithSep' was not 'lorem ipsum&dolor&sit amet'" && false)
+
+          touch $out
+        '';
+      };
 in
 
 {
@@ -196,6 +255,16 @@ in
     stdenv' = bootStdenv;
   };
 
+  test-concat-to = testConcatTo {
+    name = "test-concat-to";
+    stdenv' = bootStdenv;
+  };
+
+  test-concat-strings-sep = testConcatStringsSep {
+    name = "test-concat-strings-sep";
+    stdenv' = bootStdenv;
+  };
+
   test-structured-env-attrset = testEnvAttrset {
     name = "test-structured-env-attrset";
     stdenv' = bootStdenv;
@@ -255,6 +324,29 @@ in
       };
     };
 
+    test-concat-to = testConcatTo {
+      name = "test-concat-to-structuredAttrsByDefault";
+      stdenv' = bootStdenvStructuredAttrsByDefault;
+      extraAttrs = {
+        # test that whitespace is kept in the bash array for structuredAttrs
+        listWithSpaces = [ "c c" "d d" ];
+        extraTest = ''
+          declare -a flagsWithSpaces
+          concatTo flagsWithSpaces string listWithSpaces
+          declare -p flagsWithSpaces
+          [[ "''${flagsWithSpaces[0]}" == "a" ]] || (echo "'\$flagsWithSpaces[0]' was not 'a'" && false)
+          [[ "''${flagsWithSpaces[1]}" == "b" ]] || (echo "'\$flagsWithSpaces[1]' was not 'b'" && false)
+          [[ "''${flagsWithSpaces[2]}" == "c c" ]] || (echo "'\$flagsWithSpaces[2]' was not 'c c'" && false)
+          [[ "''${flagsWithSpaces[3]}" == "d d" ]] || (echo "'\$flagsWithSpaces[3]' was not 'd d'" && false)
+        '';
+      };
+    };
+
+    test-concat-strings-sep = testConcatStringsSep {
+      name = "test-concat-strings-sep-structuredAttrsByDefault";
+      stdenv' = bootStdenvStructuredAttrsByDefault;
+    };
+
     test-golden-example-structuredAttrs =
       let
         goldenSh = earlyPkgs.writeText "goldenSh" ''