Migrate legacy desugar wrapper to new rlocation() (bazelbuild#16025)

RELNOTES: Fix for desugaring failure on Bazel+Android+Windows build scenario.
PiperOrigin-RevId: 464654335
Change-Id: I845093b134dc68ae541603008fe7fee701c7451c

Co-authored-by: Gowroji Sunil <48122892+sgowroji@users.noreply.github.com>

tools/android/BUILD.tools

@@ -118,6 +118,7 @@ sh_binary(
     name = "desugar_java8",
     srcs = ["desugar.sh"],
     data = ["//src/tools/android/java/com/google/devtools/build/android/desugar:Desugar"],
+    deps = ["@bazel_tools//tools/bash/runfiles"],
 )
 
 alias(

tools/android/desugar.sh

@@ -17,38 +17,31 @@
 # jdk.internal.lambda.dumpProxyClasses and configures Java 8 library rewriting
 # through additional flags.
 
-# exit on errors and uninitialized variables
-set -eu
-
 RUNFILES="${RUNFILES:-$0.runfiles}"
-RUNFILES_MANIFEST_FILE="${RUNFILES_MANIFEST_FILE:-$RUNFILES/MANIFEST}"
-
-IS_WINDOWS=false
-case "$(uname | tr [:upper:] [:lower:])" in
-msys*|mingw*|cygwin*)
-  IS_WINDOWS=true
-esac
-
-if "$IS_WINDOWS" && ! type rlocation &> /dev/null; then
-  function rlocation() {
-    # Use 'sed' instead of 'awk', so if the absolute path ($2) has spaces, it
-    # will be printed completely.
-    local result="$(grep "$1" "${RUNFILES_MANIFEST_FILE}" | head -1)"
-    # If the entry has a space, it is a mapping from a runfiles-path to absolute
-    # path, otherwise it resolves to itself.
-    echo "$result" | grep -q " " \
-        && echo "$result" | sed 's/^[^ ]* //' \
-        || echo "$result"
-  }
+CHECK_FOR_EXE=0
+if [[ ! -d $RUNFILES ]]; then
+  # Try the Windows path
+  RUNFILES="${RUNFILES:-$0.exe.runfiles}"
+  CHECK_FOR_EXE=1
 fi
+RUNFILES_MANIFEST_FILE="${RUNFILES_MANIFEST_FILE:-$RUNFILES/MANIFEST}"
+export JAVA_RUNFILES=$RUNFILES
+export RUNFILES_LIB_DEBUG=1
+# --- begin runfiles.bash initialization v2 ---
+# Copy-pasted from the Bazel Bash runfiles library v2.
+set -uo pipefail; f=bazel_tools/tools/bash/runfiles/runfiles.bash
+source "${RUNFILES_DIR:-/dev/null}/$f" 2>/dev/null || \
+  source "$(grep -sm1 "^$f " "${RUNFILES_MANIFEST_FILE:-/dev/null}" | cut -f2- -d' ')" 2>/dev/null || \
+  source "$0.runfiles/$f" 2>/dev/null || \
+  source "$(grep -sm1 "^$f " "$0.runfiles_manifest" | cut -f2- -d' ')" 2>/dev/null || \
+  source "$(grep -sm1 "^$f " "$0.exe.runfiles_manifest" | cut -f2- -d' ')" 2>/dev/null || \
+  { echo>&2 "ERROR: cannot find $f"; exit 1; }; f=; set -e
+# --- end runfiles.bash initialization v2 ---
 
-# Find script to call:
-#   Windows (in MANIFEST):  <repository_name>/<path/to>/tool
-#   Linux/MacOS (symlink):  ${RUNFILES}/<repository_name>/<path/to>/tool
-if "$IS_WINDOWS"; then
-  DESUGAR="$(rlocation "[^/]*/src/tools/android/java/com/google/devtools/build/android/desugar/Desugar")"
+if [[ $CHECK_FOR_EXE -eq 0 ]]; then
+  DESUGAR="$(rlocation "bazel_tools/src/tools/android/java/com/google/devtools/build/android/desugar/Desugar")"
 else
-  DESUGAR="$(find "${RUNFILES}" -path "*/src/tools/android/java/com/google/devtools/build/android/desugar/Desugar" | head -1)"
+  DESUGAR="$(rlocation "bazel_tools/src/tools/android/java/com/google/devtools/build/android/desugar/Desugar.exe")"
 fi
 
 readonly TMPDIR="$(mktemp -d)"
@@ -118,3 +111,4 @@ fi
     "--jvm_flag=-Djdk.internal.lambda.dumpProxyClasses=${TMPDIR}" \
     "$@" \
     "${DESUGAR_JAVA8_LIBS_CONFIG[@]}"
+