Add test cases for SECTION UNION defining multiple identical labels (#1349)

Exported labels should fail to link; non-exported ones should be okay.

test/link/.gitignore

@@ -0,0 +1,2 @@
+# Test binaries
+/unmangle

test/link/section-union/same-export/a.asm

@@ -0,0 +1,5 @@
+SECTION UNION "test", WRAM0
+Same::
+	ds 1
+Foo::
+	ds 2

test/link/section-union/same-export/b.asm

@@ -0,0 +1,5 @@
+SECTION UNION "test", WRAM0
+Same::
+	ds 2
+Bar::
+	ds 1

test/link/section-union/same-export/out.err

@@ -0,0 +1 @@
+error: "Same" both in section-union/same-export/a.o from section-union/same-export/a.asm(2) and in section-union/same-export/b.o from section-union/same-export/b.asm(2)

test/link/section-union/same-label/a.asm

@@ -0,0 +1,5 @@
+SECTION UNION "test", WRAM0
+Same:
+	ds 1
+Foo:
+	ds 2

test/link/section-union/same-label/b.asm

@@ -0,0 +1,5 @@
+SECTION UNION "test", WRAM0
+Same:
+	ds 2
+Bar:
+	ds 1

test/link/test.sh

@@ -3,6 +3,8 @@
 export LC_ALL=C
 set -o pipefail
 
+[[ -e ./unmangle ]] || make -C ../.. test/link/unmangle || exit
+
 otemp="$(mktemp)"
 gbtemp="$(mktemp)"
 gbtemp2="$(mktemp)"
@@ -82,6 +84,16 @@ evaluateTest () {
 	fi
 }
 
+substPath () {
+	# Escape regex metacharacters
+	subst="$(printf '%s\n' "$1" | sed 's:[][\/.^$*]:\\&:g')"
+	# Replace the file name with a different one to match changed output
+	sed -i'' -e "s|$subst|$2|g" "$3"
+	# Escape regex metacharacters in the un-MinGW-mangled path
+	subst="$(./unmangle "$1" | sed 's:[][\/.^$*]:\\&:g')"
+	sed -i'' -e "s|$subst|$2|g" "$3"
+}
+
 for i in *.asm; do
 	test=${i%.asm}
 	startTest
@@ -215,6 +227,28 @@ rgblinkQuiet -o "$gbtemp" "$otemp" "$gbtemp2"
 tryCmpRom "$test"/ref.out.bin
 evaluateTest
 
+test="section-union/same-export"
+startTest
+"$RGBASM" -o "$otemp" "$test"/a.asm
+"$RGBASM" -o "$gbtemp2" "$test"/b.asm
+continueTest
+rgblinkQuiet "$gbtemp2" "$otemp" 2>"$outtemp"
+substPath "$otemp" "$test/a.o" "$outtemp"
+substPath "$gbtemp2" "$test/b.o" "$outtemp"
+tryDiff "$test"/out.err "$outtemp"
+evaluateTest
+
+test="section-union/same-label"
+startTest
+"$RGBASM" -o "$otemp" "$test"/a.asm
+"$RGBASM" -o "$gbtemp2" "$test"/b.asm
+continueTest
+rgblinkQuiet "$gbtemp2" "$otemp" 2>"$outtemp"
+substPath "$otemp" "$test/a.o" "$outtemp"
+substPath "$gbtemp2" "$test/b.o" "$outtemp"
+tryDiff "$test"/out.err "$outtemp"
+evaluateTest
+
 for i in section-union/*.asm; do
 	test=${i%.asm}
 	startTest

test/link/unmangle.cpp

@@ -0,0 +1,16 @@
+#include <stdio.h>
+
+/**
+ * MinGW mangles path names before passing them as command-line arguments.
+ * Some RGBLINK warning/error messages include those mangled paths on Windows.
+ * We need to see those mangled paths in test.sh to replace them with placeholders.
+ * This tool simply echoes each argument, which will be mangled iff they are paths.
+ * (For example, the "/tmp/foo" will be unmangled to something like
+ * "C:/Users/RUNNER~1/AppData/Local/Temp/foo".)
+ */
+
+int main(int argc, char *argv[]) {
+	for (int i = 1; i < argc; i++)
+		puts(argv[i]);
+	return 0;
+}