From bc4e860af5ff2582ce17b1a68e8ae88f85f88b9a Mon Sep 17 00:00:00 2001
From: Nick Gasson <nick@nickg.me.uk>
Date: Sun, 19 Mar 2023 14:56:47 +0000
Subject: [PATCH] Warn on possible multi-byte UTF-8 characters in input

---
 src/lexer.l           | 18 ++++++++++++++++++
 test/charset/utf8.vhd |  4 ++++
 test/test_charset.c   | 22 ++++++++++++++++++++++
 3 files changed, 44 insertions(+)
 create mode 100644 test/charset/utf8.vhd

diff --git a/src/lexer.l b/src/lexer.l
index 48cb0491..3d8dd4d5 100644
--- a/src/lexer.l
+++ b/src/lexer.l
@@ -78,6 +78,7 @@ static int parse_decimal_literal(const char *str);
 static int parse_based_literal(const char *str);
 static int resolve_ir1045(void);
 static void warn_lrm(vhdl_standard_t std, const char *fmt, ...);
+static void warn_utf8(const char *str);
 static bool begin_psl_comment(void);
 
 static int last_token = -1;
@@ -112,6 +113,7 @@ COVERAGE_OFF    {PRAGMA}(?i:coverage)[ \t]+(?i:off).*
 COVERAGE_ON     {PRAGMA}(?i:coverage)[ \t]+(?i:on).*
 PSL_COMMENT     {PRAGMA}(?i:psl)[ \t]+
 PSL_CONT        ^{SPACE}*({PSL_COMMENT}|"--")
+UTF8_MB         [\x80-\xff][\x80-\xbf]{1,3}
 
 %x COMMENT C_COMMENT PSL VLOG
 
@@ -492,6 +494,8 @@ COVER         ?i:cover
 <PSL>{SEVERITY}          { TOKEN(tSEVERITY); }
 <PSL>{REPORT}            { TOKEN(tREPORT); }
 
+<INITIAL,PSL>{UTF8_MB}   { warn_utf8(yytext); REJECT; }
+
 <INITIAL,PSL>{VHDL_ID}   { return parse_id(yytext); }
 {EXID}                   { return parse_ex_id(yytext); }
 <*>{SPACE}               { }
@@ -726,6 +730,20 @@ static void warn_lrm(vhdl_standard_t std, const char *fmt, ...)
    va_end(ap);
 }
 
+static void warn_utf8(const char *text)
+{
+   static bool warned = false;
+
+   if (!warned) {
+      diag_t *d = diag_new(DIAG_WARN, &yylloc);
+      diag_printf(d, "possible multi-byte UTF-8 character found in input");
+      diag_hint(d, NULL, "the native encoding of VHDL is ISO-8859-1");
+      diag_emit(d);
+
+      warned = true;
+   }
+}
+
 void reset_scanner(void)
 {
    YY_FLUSH_BUFFER;
diff --git a/test/charset/utf8.vhd b/test/charset/utf8.vhd
new file mode 100644
index 00000000..19c6c874
--- /dev/null
+++ b/test/charset/utf8.vhd
@@ -0,0 +1,4 @@
+-- -*- coding: utf-8 -*-
+package test is
+    constant Åxyzß : bit := '1';          -- Warning
+end package;
diff --git a/test/test_charset.c b/test/test_charset.c
index adabef4b..cd1217c0 100644
--- a/test/test_charset.c
+++ b/test/test_charset.c
@@ -54,12 +54,34 @@ START_TEST(test_iso88591)
 }
 END_TEST
 
+START_TEST(test_utf8)
+{
+   input_from_file(TESTDIR "/charset/utf8.vhd");
+
+   const error_t expect[] = {
+      {  3, "possible multi-byte UTF-8 character found in input" },
+      {  3, "unexpected error while parsing constant declaration" },
+      { -1, NULL }
+   };
+   expect_errors(expect);
+
+   tree_t p = parse();
+   fail_if(p == NULL);
+   fail_unless(tree_kind(p) == T_PACKAGE);
+
+   fail_unless(parse() == NULL);
+
+   check_expected_errors();
+}
+END_TEST
+
 Suite *get_charset_tests(void)
 {
    Suite *s = suite_create("charset");
 
    TCase *tc = nvc_unit_test();
    tcase_add_test(tc, test_iso88591);
+   tcase_add_test(tc, test_utf8);
    suite_add_tcase(s, tc);
 
    return s;
-- 
2.39.2