ci: add a parser fuzzer step too (#7288)

.github/workflows/ci.yml

@@ -622,3 +622,32 @@ jobs:
         ./v test-parser examples/vmod.v
         ./v test-parser examples/regex_example.v
         ./v test-parser examples/2048/2048.v
+
+  parser-silent-fuzzing:
+    name: Parser silent mode fuzzing
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    steps:
+    - uses: actions/checkout@v2
+    - name: Build local v
+      run: make -j4
+    - name: Install zzuf
+      run: sudo apt install -qq zzuf
+    - name: Run test-parser
+      run: |
+        zzuf -R '\x00-\x20\x7f-\xff' -r0.01 < examples/hello_world.v > examples/hello_world_fuzz.v
+        ./v test-parser examples/hello_world_fuzz.v
+        zzuf -R '\x00-\x20\x7f-\xff' -r0.01 < examples/hanoi.v > examples/hanoi_fuzz.v
+        ./v test-parser examples/hanoi_fuzz.v
+        zzuf -R '\x00-\x20\x7f-\xff' -r0.01 < examples/fibonacci.v > examples/fibonacci_fuzz.v
+        ./v test-parser examples/fibonacci.v
+        zzuf -R '\x00-\x20\x7f-\xff' -r0.01 < examples/cli.v > examples/cli_fuzz.v
+        ./v test-parser examples/cli_fuzz.v
+        zzuf -R '\x00-\x20\x7f-\xff' -r0.01 < examples/json.v > examples/json_fuzz.v
+        ./v test-parser examples/json.v
+        zzuf -R '\x00-\x20\x7f-\xff' -r0.01 < examples/vmod.v > examples/vmod_fuzz.v
+        ./v test-parser examples/vmod.v
+        zzuf -R '\x00-\x20\x7f-\xff' -r0.01 < examples/regex_example.v > examples/regex_example_fuzz.v
+        ./v test-parser examples/regex_example_fuzz.v
+        zzuf -R '\x00-\x20\x7f-\xff' -r0.01 < examples/2048/2048.v > examples/2048/2048_fuzz.v
+        ./v test-parser examples/2048/2048_fuzz.v

vlib/v/parser/parse_type.v

@@ -380,7 +380,7 @@ pub fn (mut p Parser) parse_generic_struct_inst_type(name string) table.Type {
 	bs_cname += '_T_'
 	mut generic_types := []table.Type{}
 	mut is_instance := false
-	for {
+	for p.tok.kind != .eof {
 		gt := p.parse_type()
 		if !gt.has_flag(.generic) {
 			is_instance = true

vlib/v/scanner/scanner.v

@@ -233,6 +233,9 @@ fn (mut s Scanner) ident_hex_number() string {
 	mut first_wrong_digit_pos := 0
 	mut first_wrong_digit := `\0`
 	start_pos := s.pos
+	if s.pos + 2 >= s.text.len {
+		return '0x'
+	}
 	s.pos += 2 // skip '0x'
 	if s.text[s.pos] == num_sep {
 		s.error('separator `_` is only valid between digits in a numeric literal')