Sort rblf_wildcard results and remove file existence functions

Kati's $(wildcard) results are guaranteed to be sorted,
but go's filepath.Glob() is not.

Remove the file existence functions because they can
just be replaced with wildcards.

Bug: 226974242
Test: go test
Change-Id: I02fb6292b932bc28cd856ec3c7cb9ed9e96ca630

tools/rbcrun/host.go

@@ -20,6 +20,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"sort"
 	"strings"
 
 	"go.starlark.net/starlark"
@@ -111,19 +112,6 @@ func loader(thread *starlark.Thread, module string) (starlark.StringDict, error)
 	return e.globals, e.err
 }
 
-// fileExists returns True if file with given name exists.
-func fileExists(_ *starlark.Thread, b *starlark.Builtin, args starlark.Tuple,
-	kwargs []starlark.Tuple) (starlark.Value, error) {
-	var path string
-	if err := starlark.UnpackPositionalArgs(b.Name(), args, kwargs, 1, &path); err != nil {
-		return starlark.None, err
-	}
-	if _, err := os.Stat(path); err != nil {
-		return starlark.False, nil
-	}
-	return starlark.True, nil
-}
-
 // wildcard(pattern, top=None) expands shell's glob pattern. If 'top' is present,
 // the 'top/pattern' is globbed and then 'top/' prefix is removed.
 func wildcard(_ *starlark.Thread, b *starlark.Builtin, args starlark.Tuple,
@@ -150,6 +138,10 @@ func wildcard(_ *starlark.Thread, b *starlark.Builtin, args starlark.Tuple,
 			files[i] = strings.TrimPrefix(files[i], prefix)
 		}
 	}
+	// Kati uses glob(3) with no flags, which means it's sorted
+	// because GLOB_NOSORT is not passed. Go's glob is not
+	// guaranteed to sort the results.
+	sort.Strings(files)
 	return makeStringList(files), nil
 }
 
@@ -269,8 +261,6 @@ func setup(env []string) {
 		"struct":   starlark.NewBuiltin("struct", starlarkstruct.Make),
 		"rblf_cli": structFromEnv(env),
 		"rblf_env": structFromEnv(os.Environ()),
-		// To convert makefile's $(wildcard foo)
-		"rblf_file_exists": starlark.NewBuiltin("rblf_file_exists", fileExists),
 		// To convert find-copy-subdir and product-copy-files-by pattern
 		"rblf_find_files": starlark.NewBuiltin("rblf_find_files", find),
 		// To convert makefile's $(shell cmd)

tools/rbcrun/testdata/file_ops.star

@@ -4,9 +4,6 @@ load("assert.star", "assert")
 
 def test():
     myname = "file_ops.star"
-    assert.true(rblf_file_exists("."), "./ exists ")
-    assert.true(rblf_file_exists(myname), "the file %s does exist" % myname)
-    assert.true(not rblf_file_exists("no_such_file"), "the file no_such_file does not exist")
     files = rblf_wildcard("*.star")
     assert.true(myname in files, "expected %s in  %s" % (myname, files))
     files = rblf_wildcard("*.star", rblf_env.TEST_DATA_DIR)

tools/rbcrun/testdata/module1.star

@@ -2,6 +2,6 @@
 load("assert.star", "assert")
 
 # Make sure that builtins are defined for the loaded module, too
-assert.true(rblf_file_exists("module1.star"))
-assert.true(not rblf_file_exists("no_such file"))
+assert.true(rblf_wildcard("module1.star"))
+assert.true(not rblf_wildcard("no_such file"))
 test = "module1"