Upstream patch: https://sourceforge.net/u/vic5/scintilla/ci/6d0ce3c92a1371372bd601cd572a078d5e4041a4/
Upstream issue: https://sourceforge.net/p/scintilla/bugs/2019/
Codeblocks forum discussion: https://forums.codeblocks.org/index.php?topic=24505.0

lexers/LexMMIXAL.cxxDiffSwitch to side-by-side view
--- a/src/sdk/wxscintilla/src/scintilla/lexers/LexMMIXAL.cxx
+++ b/src/sdk/wxscintilla/src/scintilla/lexers/LexMMIXAL.cxx
@@ -99,12 +99,11 @@
 			}
 		} else if (sc.state == SCE_MMIXAL_REF) {			// REF
 			if (!IsAWordChar(sc.ch) ) {
-				char s[100];
-				sc.GetCurrent(s, sizeof(s));
+				char s0[100];
+				sc.GetCurrent(s0, sizeof(s0));
+				const char *s = s0;
 				if (*s == ':') {	// ignore base prefix for match
-					for (size_t i = 0; i != sizeof(s); ++i) {
-						*(s+i) = *(s+i+1);
-					}
+					++s;
 				}
 				if (special_register.InList(s)) {
 					sc.ChangeState(SCE_MMIXAL_REGISTER);