scripts: kconfig: merge_config.sh: pass output file as awk variable

The refactoring commit 5fa9b82 ("scripts: kconfig:
merge_config.sh: refactor from shell/sed/grep to awk") passes
$TMP_FILE.new as ARGV[3] to awk, using it as both an output destination
and an input file argument. When the base file is empty, nothing is
written to ARGV[3] during processing, so awk fails trying to open it
for reading:

    awk: cmd. line:52: fatal: cannot open file
    `./.tmp.config.grcQin34jb.new' for reading: No such file or directory
    mv: cannot stat './.tmp.config.grcQin34jb.new': No such file or directory

Pass the output path via -v outfile instead and drop the FILENAME ==
ARGV[3] { nextfile }.

Fixes: 5fa9b82 ("scripts: kconfig: merge_config.sh: refactor from shell/sed/grep to awk")
Signed-off-by: Daniel Gomez <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Nathan Chancellor <[email protected]>

Author: dagomez137

scripts/kconfig/merge_config.sh

@@ -151,6 +151,7 @@ for ORIG_MERGE_FILE in $MERGE_LIST ; do
 	if ! "$AWK" -v prefix="$CONFIG_PREFIX" \
 		-v warnoverride="$WARNOVERRIDE" \
 		-v strict="$STRICT" \
+		-v outfile="$TMP_FILE.new" \
 		-v builtin="$BUILTIN" \
 		-v warnredun="$WARNREDUN" '
 	BEGIN {
@@ -212,7 +213,7 @@ for ORIG_MERGE_FILE in $MERGE_LIST ; do
 
 		# Not a config or not in merge file - keep it
 		if (cfg == "" || !(cfg in merge_cfg)) {
-			print $0 >> ARGV[3]
+			print $0 >> outfile
 			next
 		}
 
@@ -222,7 +223,7 @@ for ORIG_MERGE_FILE in $MERGE_LIST ; do
 		# BUILTIN: do not demote y to m
 		if (builtin == "true" && new_val ~ /=m$/ && prev_val ~ /=y$/) {
 			warn_builtin(cfg, prev_val, new_val)
-			print $0 >> ARGV[3]
+			print $0 >> outfile
 			skip_merge[merge_cfg_line[cfg]] = 1
 			next
 		}
@@ -235,7 +236,7 @@ for ORIG_MERGE_FILE in $MERGE_LIST ; do
 
 		# "=n" is the same as "is not set"
 		if (prev_val ~ /=n$/ && new_val ~ / is not set$/) {
-			print $0 >> ARGV[3]
+			print $0 >> outfile
 			next
 		}
 
@@ -246,25 +247,20 @@ for ORIG_MERGE_FILE in $MERGE_LIST ; do
 		}
 	}
 
-	# output file, skip all lines
-	FILENAME == ARGV[3] {
-		nextfile
-	}
-
 	END {
 		# Newline in case base file lacks trailing newline
-		print "" >> ARGV[3]
+		print "" >> outfile
 		# Append merge file, skipping lines marked for builtin preservation
 		for (i = 1; i <= merge_total; i++) {
 			if (!(i in skip_merge)) {
-				print merge_lines[i] >> ARGV[3]
+				print merge_lines[i] >> outfile
 			}
 		}
 		if (strict_violated) {
 			exit 1
 		}
 	}' \
-	"$ORIG_MERGE_FILE" "$TMP_FILE" "$TMP_FILE.new"; then
+	"$ORIG_MERGE_FILE" "$TMP_FILE"; then
 		# awk exited non-zero, strict mode was violated
 		STRICT_MODE_VIOLATED=true
 	fi