Codegen: use plain grep instead of git grep

Some consumers want to operate across repositories, so git just gets in
the way.

staging/src/k8s.io/code-generator/kube_codegen.sh

@@ -34,10 +34,13 @@ function kube::codegen::internal::git_find() {
     git ls-files -cmo --exclude-standard "$@"
 }
 
-function kube::codegen::internal::git_grep() {
-    # We want to include modified and untracked files because this might be
-    # running against code which is not tracked by git yet.
-    git grep --untracked "$@" ":(exclude)vendor/"
+function kube::codegen::internal::grep() {
+    # We use `grep` rather than `git grep` because sometimes external projects
+    # use this across repos.
+    grep "$@" \
+        --exclude-dir .git \
+        --exclude-dir _output \
+        --exclude-dir vendor
 }
 
 # Generate tagged helper code: conversions, deepcopy, and defaults
@@ -127,9 +130,10 @@ function kube::codegen::gen_helpers() {
         pkg="$(cd "${dir}" && GO111MODULE=on go list -find .)"
         input_pkgs+=("${pkg}")
     done < <(
-        ( kube::codegen::internal::git_grep -l --null \
+        ( kube::codegen::internal::grep -l --null \
             -e '+k8s:deepcopy-gen=' \
-            ":(glob)${root}"/'**/*.go' \
+            -r "${root}" \
+            --include '*.go' \
             || true \
         ) | while read -r -d $'\0' F; do dirname "${F}"; done \
           | LC_ALL=C sort -u
@@ -161,9 +165,10 @@ function kube::codegen::gen_helpers() {
         pkg="$(cd "${dir}" && GO111MODULE=on go list -find .)"
         input_pkgs+=("${pkg}")
     done < <(
-        ( kube::codegen::internal::git_grep -l --null \
+        ( kube::codegen::internal::grep -l --null \
             -e '+k8s:defaulter-gen=' \
-            ":(glob)${root}"/'**/*.go' \
+            -r "${root}" \
+            --include '*.go' \
             || true \
         ) | while read -r -d $'\0' F; do dirname "${F}"; done \
           | LC_ALL=C sort -u
@@ -195,9 +200,10 @@ function kube::codegen::gen_helpers() {
         pkg="$(cd "${dir}" && GO111MODULE=on go list -find .)"
         input_pkgs+=("${pkg}")
     done < <(
-        ( kube::codegen::internal::git_grep -l --null \
+        ( kube::codegen::internal::grep -l --null \
             -e '+k8s:conversion-gen=' \
-            ":(glob)${root}"/'**/*.go' \
+            -r "${root}" \
+            --include '*.go' \
             || true \
         ) | while read -r -d $'\0' F; do dirname "${F}"; done \
           | LC_ALL=C sort -u
@@ -357,9 +363,10 @@ function kube::codegen::gen_openapi() {
         pkg="$(cd "${dir}" && GO111MODULE=on go list -find .)"
         input_pkgs+=("${pkg}")
     done < <(
-        ( kube::codegen::internal::git_grep -l --null \
+        ( kube::codegen::internal::grep -l --null \
             -e '+k8s:openapi-gen=' \
-            ":(glob)${root}"/'**/*.go' \
+            -r "${root}" \
+            --include '*.go' \
             || true \
         ) | while read -r -d $'\0' F; do dirname "${F}"; done \
           | LC_ALL=C sort -u
@@ -566,9 +573,10 @@ function kube::codegen::gen_client() {
             group_versions+=("${leaf2}/${leaf}")
         fi
     done < <(
-        ( kube::codegen::internal::git_grep -l --null \
+        ( kube::codegen::internal::grep -l --null \
             -e '+genclient' \
-            ":(glob)${in_root}${one_input_api}"/'**/*.go' \
+            -r "${in_root}${one_input_api}" \
+            --include '*.go' \
             || true \
         ) | while read -r -d $'\0' F; do dirname "${F}"; done \
           | LC_ALL=C sort -u
@@ -584,9 +592,10 @@ function kube::codegen::gen_client() {
 
         echo "Generating applyconfig code for ${#input_pkgs[@]} targets"
 
-        ( kube::codegen::internal::git_grep -l --null \
+        ( kube::codegen::internal::grep -l --null \
             -e '^// Code generated by applyconfiguration-gen. DO NOT EDIT.$' \
-            ":(glob)${out_root}/${applyconfig_subdir}"/'**/*.go' \
+            -r "${out_root}/${applyconfig_subdir}" \
+            --include '*.go' \
             || true \
         ) | xargs -0 rm -f
 
@@ -604,9 +613,10 @@ function kube::codegen::gen_client() {
 
     echo "Generating client code for ${#group_versions[@]} targets"
 
-    ( kube::codegen::internal::git_grep -l --null \
+    ( kube::codegen::internal::grep -l --null \
         -e '^// Code generated by client-gen. DO NOT EDIT.$' \
-        ":(glob)${out_root}/${clientset_subdir}"/'**/*.go' \
+        -r "${out_root}/${clientset_subdir}" \
+        --include '*.go' \
         || true \
     ) | xargs -0 rm -f
 
@@ -627,9 +637,10 @@ function kube::codegen::gen_client() {
     if [ "${watchable}" == "true" ]; then
         echo "Generating lister code for ${#input_pkgs[@]} targets"
 
-        ( kube::codegen::internal::git_grep -l --null \
+        ( kube::codegen::internal::grep -l --null \
             -e '^// Code generated by lister-gen. DO NOT EDIT.$' \
-            ":(glob)${out_root}/${listers_subdir}"/'**/*.go' \
+            -r "${out_root}/${listers_subdir}" \
+            --include '*.go' \
             || true \
         ) | xargs -0 rm -f
 
@@ -646,9 +657,10 @@ function kube::codegen::gen_client() {
 
         echo "Generating informer code for ${#input_pkgs[@]} targets"
 
-        ( kube::codegen::internal::git_grep -l --null \
+        ( kube::codegen::internal::grep -l --null \
             -e '^// Code generated by informer-gen. DO NOT EDIT.$' \
-            ":(glob)${out_root}/${informers_subdir}"/'**/*.go' \
+            -r "${out_root}/${informers_subdir}" \
+            --include '*.go' \
             || true \
         ) | xargs -0 rm -f