optgen: make more sanity checks for enums.

* opt-functions.awk (opt_args_non_empty): New function.
	* opt-read.awk: Use the function for various option arguments.

gcc/ChangeLog

@@ -1,3 +1,8 @@
+2020-05-05  Martin Liska  <mliska@suse.cz>
+
+	* opt-functions.awk (opt_args_non_empty): New function.
+	* opt-read.awk: Use the function for various option arguments.
+
 2020-05-05  Martin Liska  <mliska@suse.cz>
 
 	PR driver/94330

gcc/opt-functions.awk

@@ -72,6 +72,16 @@ function opt_args(name, flags)
 	return flags
 }
 
+# If FLAGS contains a "NAME(...argument...)" flag, return the value
+# of the argument.  Print error message otherwise.
+function opt_args_non_empty(name, flags, description)
+{
+	args = opt_args(name, flags)
+	if (args == "")
+		print "#error Empty option argument '" name "' during parsing of: " flags
+	return args
+}
+
 # Return the Nth comma-separated element of S.  Return the empty string
 # if S does not contain N elements.
 function nth_arg(n, s)

gcc/opt-read.awk

@@ -81,8 +81,8 @@ BEGIN {
 		}
 		else if ($1 == "Enum") {
 			props = $2
-			name = opt_args("Name", props)
+			name = opt_args_non_empty("Name", props)
-			type = opt_args("Type", props)
+			type = opt_args_non_empty("Type", props)
 			unknown_error = opt_args("UnknownError", props)
 			enum_names[n_enums] = name
 			enum_type[name] = type
@@ -93,9 +93,9 @@ BEGIN {
 		}
 		else if ($1 == "EnumValue")  {
 			props = $2
-			enum_name = opt_args("Enum", props)
+			enum_name = opt_args_non_empty("Enum", props)
-			string = opt_args("String", props)
+			string = opt_args_non_empty("String", props)
-			value = opt_args("Value", props)
+			value = opt_args_non_empty("Value", props)
 			val_flags = "0"
 			val_flags = val_flags \
 			  test_flag("Canonical", props, "| CL_ENUM_CANONICAL") \