Improve the error messages for interpolating undefined or invalid symbols (#1423)

src/asm/lexer.cpp

@@ -1208,7 +1208,7 @@ static std::shared_ptr<std::string> readInterpolation(size_t depth) {
 
 	Symbol const *sym = sym_FindScopedValidSymbol(fmtBuf);
 
-	if (!sym) {
+	if (!sym || !sym->isDefined()) {
 		error("Interpolated symbol \"%s\" does not exist\n", fmtBuf.c_str());
 	} else if (sym->type == SYM_EQUS) {
 		auto buf = std::make_shared<std::string>();
@@ -1219,7 +1219,7 @@ static std::shared_ptr<std::string> readInterpolation(size_t depth) {
 		fmt.appendNumber(*buf, sym->getConstantValue());
 		return buf;
 	} else {
-		error("Only numerical and string symbols can be interpolated\n");
+		error("Interpolated symbol \"%s\" is not a numeric or string symbol\n", fmtBuf.c_str());
 	}
 	return nullptr;
 }

test/asm/interpolation.asm

@@ -1,4 +1,4 @@
-SECTION "Test", ROM0
+SECTION "Test", ROM0[123]
 
 def NAME equs "ITEM"
 def FMT equs "d"
@@ -14,6 +14,15 @@ PRINTLN STRCAT("{NAME}_{d:INDEX}", " is ", {NAME}_{d:INDEX})
 PURGE {NAME}_{d:INDEX}
 ASSERT !DEF({NAME}_{d:INDEX})
 
+; undefined
+PRINTLN "undef {undef}"
+
+; referenced but undefined
+ld hl, label
+PRINTLN "label {label}"
+label::
+PRINTLN "label {label}"
+
 ; not string or number
 MACRO foo
 ENDM

test/asm/interpolation.err

@@ -1,3 +1,7 @@
-error: interpolation.asm(20):
-    Only numerical and string symbols can be interpolated
-error: Assembly aborted (1 error)!
+error: interpolation.asm(18):
+    Interpolated symbol "undef" does not exist
+error: interpolation.asm(22):
+    Interpolated symbol "label" does not exist
+error: interpolation.asm(29):
+    Interpolated symbol "foo" is not a numeric or string symbol
+error: Assembly aborted (3 errors)!

test/asm/interpolation.out

@@ -1,2 +1,5 @@
 ITEM_100 is hundredth
+undef 
+label 
+label $7E
 foo