From 889dd83798f108d1d26bba84b6412b36a03e87b8 Mon Sep 17 00:00:00 2001
From: dbrotz <43593771+dbrotz@users.noreply.github.com>
Date: Mon, 9 Sep 2019 09:46:18 -0700
Subject: [PATCH] Print useful error message when '\0' is used in a symbol name
 AppendMacroArg() was passing 0 to sym_FindMacroArg(), which caused an
 assertion failure. Now, AppendMacroArg() prints an error message instead.

---
 src/asm/globlex.c                     | 4 ++--
 test/asm/symbol-invalid-macro-arg.asm | 1 +
 test/asm/symbol-invalid-macro-arg.out | 2 ++
 3 files changed, 5 insertions(+), 2 deletions(-)
 create mode 100644 test/asm/symbol-invalid-macro-arg.asm
 create mode 100644 test/asm/symbol-invalid-macro-arg.out

diff --git a/src/asm/globlex.c b/src/asm/globlex.c
index 17032553..14f45c5d 100644
--- a/src/asm/globlex.c
+++ b/src/asm/globlex.c
@@ -198,10 +198,10 @@ char *AppendMacroArg(char whichArg, char *dest, size_t *destIndex)
 
 	if (whichArg == '@')
 		marg = sym_FindMacroArg(-1);
-	else if (whichArg >= '0' && whichArg <= '9')
+	else if (whichArg >= '1' && whichArg <= '9')
 		marg = sym_FindMacroArg(whichArg - '0');
 	else
-		fatalerror("Malformed ID");
+		fatalerror("Invalid macro argument '\\%c' in symbol", whichArg);
 
 	if (!marg)
 		fatalerror("Macro argument '\\%c' not defined", whichArg);
diff --git a/test/asm/symbol-invalid-macro-arg.asm b/test/asm/symbol-invalid-macro-arg.asm
new file mode 100644
index 00000000..6806b7e3
--- /dev/null
+++ b/test/asm/symbol-invalid-macro-arg.asm
@@ -0,0 +1 @@
+x\0
diff --git a/test/asm/symbol-invalid-macro-arg.out b/test/asm/symbol-invalid-macro-arg.out
new file mode 100644
index 00000000..ff94c3c2
--- /dev/null
+++ b/test/asm/symbol-invalid-macro-arg.out
@@ -0,0 +1,2 @@
+ERROR: symbol-invalid-macro-arg.asm(1):
+    Invalid macro argument '\0' in symbol