Sort .sym files in ascending order, and test for it (#1355)

test/link/symbols/a.asm

@@ -0,0 +1,15 @@
+SECTION "alpha", ROM0
+Alpha::
+	db 1, 2, 3
+End:
+
+SECTION "a", WRAM0
+wAlpha::
+	ds 3
+.End::
+
+SECTION UNION "U", WRAM0
+wStart:
+	.word1: dw
+	.word2: dw
+wEnd:

test/link/symbols/b.asm

@@ -0,0 +1,14 @@
+SECTION "beta", ROM0
+Beta::
+	db 4, 5, 6
+End:
+
+SECTION "b", WRAM0
+wBeta::
+	ds 3
+.End::
+
+SECTION UNION "U", WRAM0
+wStart:
+	.long1: dl
+wEnd:

test/link/symbols/ref.out.sym

@@ -0,0 +1,16 @@
+; File generated by rgblink
+00:0000 Beta
+00:0003 End
+00:0003 Alpha
+00:0006 End
+00:c000 wStart
+00:c000 wStart
+00:c000 wStart.long1
+00:c000 wStart.word1
+00:c002 wStart.word2
+00:c004 wEnd
+00:c004 wEnd
+00:c004 wBeta
+00:c007 wBeta.End
+00:c007 wAlpha
+00:c00a wAlpha.End

test/link/test.sh

@@ -9,13 +9,14 @@ otemp="$(mktemp)"
 gbtemp="$(mktemp)"
 gbtemp2="$(mktemp)"
 outtemp="$(mktemp)"
+outtemp2="$(mktemp)"
 tests=0
 failed=0
 rc=0
 
 # Immediate expansion is the desired behavior.
 # shellcheck disable=SC2064
-trap "rm -f ${otemp@Q} ${gbtemp@Q} ${gbtemp2@Q} ${outtemp@Q}" EXIT
+trap "rm -f ${otemp@Q} ${gbtemp@Q} ${gbtemp2@Q} ${outtemp@Q} ${outtemp2@Q}" EXIT
 
 bold="$(tput bold)"
 resbold="$(tput sgr0)"
@@ -276,6 +277,17 @@ for i in section-union/*.asm; do
 	evaluateTest
 done
 
+test="symbols"
+startTest
+"$RGBASM" -o "$otemp" "$test"/a.asm
+"$RGBASM" -o "$gbtemp2" "$test"/b.asm
+continueTest
+rgblinkQuiet -o "$gbtemp" -n "$outtemp2" "$gbtemp2" "$otemp" 2>"$outtemp"
+tryDiff "$test"/out.err "$outtemp"
+tryDiff "$test"/ref.out.sym "$outtemp2"
+tryCmpRom "$test"/ref.out.bin
+evaluateTest
+
 if [[ "$failed" -eq 0 ]]; then
 	echo "${bold}${green}All ${tests} tests passed!${rescolors}${resbold}"
 else