diff --git a/include/tao/pegtl/internal/unhex_utility.hpp b/include/tao/pegtl/internal/unhex_utility.hpp
index 674ee33c..0acd03ab 100644
--- a/include/tao/pegtl/internal/unhex_utility.hpp
+++ b/include/tao/pegtl/internal/unhex_utility.hpp
@@ -44,8 +44,12 @@ namespace TAO_PEGTL_NAMESPACE::internal
    }
 
    template< typename I >
-   [[nodiscard]] constexpr I unhex_string_impl( const char* begin, const char* end, I result = 0 )
+   [[nodiscard]] constexpr I unhex_string_impl( const char* begin, const char* end )
    {
+      if( begin == end ) {
+         return 0;
+      }
+      I result = unhex_char_impl< I >( *begin++ );
       while( begin != end ) {
          result <<= 4;
          result += unhex_char_impl< I >( *begin++ );
diff --git a/src/example/pegtl/iri.cpp b/src/example/pegtl/iri.cpp
index bb5517f8..7c1f0d9d 100644
--- a/src/example/pegtl/iri.cpp
+++ b/src/example/pegtl/iri.cpp
@@ -31,7 +31,7 @@ struct IRI
    std::string query;
    std::string fragment;
 
-   explicit IRI( pegtl::argv_input< pegtl::scan::lf_crlf >& );
+   explicit IRI( pegtl::argv_input< pegtl::scan::lf_crlf >& in );
 };
 
 namespace iri
diff --git a/src/example/pegtl/token_input_1.cpp b/src/example/pegtl/token_input_1.cpp
index c359b0e0..0cfbcd3a 100644
--- a/src/example/pegtl/token_input_1.cpp
+++ b/src/example/pegtl/token_input_1.cpp
@@ -95,7 +95,7 @@ struct my_grammar
 int main()
 {
    const std::vector< my_token > v{
-      { my_type::beta, "first" },
+      { my_type::beta,  "first" },
       { my_type::beta, "second" }
    };
    token_input< my_token > in( v );
diff --git a/src/example/pegtl/token_input_2.cpp b/src/example/pegtl/token_input_2.cpp
index da599903..6f3e49af 100644
--- a/src/example/pegtl/token_input_2.cpp
+++ b/src/example/pegtl/token_input_2.cpp
@@ -65,7 +65,7 @@ struct my_grammar
 int main()
 {
    const std::vector< my_token > v{
-      { my_type::beta, "first" },
+      { my_type::beta,  "first" },
       { my_type::beta, "second" }
    };
    token_input in( v );
diff --git a/src/example/pegtl/uri.cpp b/src/example/pegtl/uri.cpp
index ef14afa1..5d5f95b5 100644
--- a/src/example/pegtl/uri.cpp
+++ b/src/example/pegtl/uri.cpp
@@ -30,7 +30,7 @@ struct URI
    std::string query;
    std::string fragment;
 
-   explicit URI( pegtl::argv_input< pegtl::scan::lf_crlf >& );
+   explicit URI( pegtl::argv_input< pegtl::scan::lf_crlf >& in );
 };
 
 namespace uri
diff --git a/src/test/pegtl/action_apply_2.cpp b/src/test/pegtl/action_apply_2.cpp
index 6f6f162b..c82af681 100644
--- a/src/test/pegtl/action_apply_2.cpp
+++ b/src/test/pegtl/action_apply_2.cpp
@@ -91,7 +91,12 @@ namespace TAO_PEGTL_NAMESPACE
       }
 
       std::size_t count = 0;
-      text_position pos[] = { { 1, 1, 0 }, { 1, 2, 1 }, { 2, 1, 2 }, { 2, 2, 3 } };
+      text_position pos[] = {
+         {1,  1, 0},
+         { 1, 2, 1},
+         { 2, 1, 2},
+         { 2, 2, 3}
+      };
 
       template< typename Rule >
       struct count_action
diff --git a/src/test/pegtl/ascii_atomics.cpp b/src/test/pegtl/ascii_atomics.cpp
index ac758c0f..4c4a3edf 100644
--- a/src/test/pegtl/ascii_atomics.cpp
+++ b/src/test/pegtl/ascii_atomics.cpp
@@ -43,7 +43,7 @@ namespace TAO_PEGTL_NAMESPACE
       verify_rule< ascii::ranges< 'a', 'z', '4' > >( __LINE__, __FILE__, "", result_type::local_failure, 0 );
 
       for( int i = 0; i < 128; ++i ) {
-         const int c = char( i );
+         const auto c = char( i );
 
          const bool is_one = ( c == '#' ) || ( c == 'a' ) || ( c == ' ' );
          const bool is_range = ( 20 <= c ) && ( c <= 120 );
diff --git a/src/test/pegtl/ascii_classes.cpp b/src/test/pegtl/ascii_classes.cpp
index b0292ad4..7b142e27 100644
--- a/src/test/pegtl/ascii_classes.cpp
+++ b/src/test/pegtl/ascii_classes.cpp
@@ -45,7 +45,7 @@ namespace TAO_PEGTL_NAMESPACE
       verify_rule< ascii::xdigit >( __LINE__, __FILE__, "", result_type::local_failure, 0 );
 
       for( int i = 0; i < 128; ++i ) {
-         const int c = char( i );
+         const auto c = char( i );  // NOLINT(bugprone-signed-char-misuse)
 
          const bool is_blank = ( c == ' ' ) || ( c == '\t' );
          const bool is_digit = ( '0' <= c ) && ( c <= '9' );
diff --git a/src/test/pegtl/buffer_buffer_common.cpp b/src/test/pegtl/buffer_buffer_common.cpp
index 6da7c4ab..143c1c5a 100644
--- a/src/test/pegtl/buffer_buffer_common.cpp
+++ b/src/test/pegtl/buffer_buffer_common.cpp
@@ -13,7 +13,7 @@
 namespace TAO_PEGTL_NAMESPACE
 {
    template< typename Buffer, typename... As >
-   void test_common( As&&... as )
+   void test_common( As&&... as )  // NOLINT(readability-function-size)
    {
       const std::string st = "abcdefghijklmnopqrstuvwxyz";
 
diff --git a/src/test/pegtl/contrib_nested_exceptions.cpp b/src/test/pegtl/contrib_nested_exceptions.cpp
index 694c6a26..8a9b3c6e 100644
--- a/src/test/pegtl/contrib_nested_exceptions.cpp
+++ b/src/test/pegtl/contrib_nested_exceptions.cpp
@@ -46,7 +46,7 @@ namespace TAO_PEGTL_NAMESPACE
    void test1()
    {
       try {
-         throw s1;
+         throw std::string( s1 );
       }
       catch( ... ) {
          visitor v;
@@ -60,7 +60,7 @@ namespace TAO_PEGTL_NAMESPACE
    void test2()
    {
       try {
-         throw s1;
+         throw std::string( s1 );
       }
       catch( const std::string& s ) {
          visitor v;
@@ -75,7 +75,7 @@ namespace TAO_PEGTL_NAMESPACE
    {
       try {
          try {
-            throw s1;
+            throw std::string( s1 );
          }
          catch( ... ) {
             std::throw_with_nested( std::runtime_error( s2 ) );
diff --git a/src/test/pegtl/internal_data_and_size.cpp b/src/test/pegtl/internal_data_and_size.cpp
index 9f84c13a..a9c393eb 100644
--- a/src/test/pegtl/internal_data_and_size.cpp
+++ b/src/test/pegtl/internal_data_and_size.cpp
@@ -22,7 +22,7 @@ namespace TAO_PEGTL_NAMESPACE
          static_assert( std::is_same_v< decltype( das.data() ), std::int32_t > );
          TAO_PEGTL_TEST_ASSERT( !das );
          TAO_PEGTL_TEST_ASSERT( das.empty() );
-         TAO_PEGTL_TEST_ASSERT( das.size() == 0 );
+         TAO_PEGTL_TEST_ASSERT( das.size() == 0 );  // NOLINT(readability-container-size-empty)
       }
       {
          internal::data_and_size< std::int32_t, void > das;
@@ -30,7 +30,7 @@ namespace TAO_PEGTL_NAMESPACE
          static_assert( std::is_same_v< decltype( das.data() ), const std::int32_t& > );
          TAO_PEGTL_TEST_ASSERT( !das );
          TAO_PEGTL_TEST_ASSERT( das.empty() );
-         TAO_PEGTL_TEST_ASSERT( das.size() == 0 );
+         TAO_PEGTL_TEST_ASSERT( das.size() == 0 );  // NOLINT(readability-container-size-empty)
          TAO_PEGTL_TEST_ASSERT( das.pointer() == nullptr );
       }
       {
diff --git a/src/test/pegtl/internal_extract_position.cpp b/src/test/pegtl/internal_extract_position.cpp
index d9bad689..a59d384d 100644
--- a/src/test/pegtl/internal_extract_position.cpp
+++ b/src/test/pegtl/internal_extract_position.cpp
@@ -22,7 +22,7 @@ namespace TAO_PEGTL_NAMESPACE
          return &m_int;
       }
 
-      [[nodiscard]] test_type_1 current_position() const noexcept
+      [[nodiscard]] static test_type_1 current_position() noexcept
       {
          return {};
       }
@@ -46,7 +46,7 @@ namespace TAO_PEGTL_NAMESPACE
 
    struct test_type_4
    {
-      [[nodiscard]] test_type_1 current_position() const noexcept
+      [[nodiscard]] static test_type_1 current_position() noexcept
       {
          return {};
       }
@@ -61,7 +61,7 @@ namespace TAO_PEGTL_NAMESPACE
          return &m_tok;
       }
 
-      [[nodiscard]] int current_position() const noexcept
+      [[nodiscard]] static int current_position() noexcept
       {
          return 0;
       }
@@ -86,7 +86,7 @@ namespace TAO_PEGTL_NAMESPACE
          return &m_tok;
       }
 
-      [[nodiscard]] int current_position() const noexcept
+      [[nodiscard]] static int current_position() noexcept
       {
          return 0;
       }
@@ -98,26 +98,31 @@ namespace TAO_PEGTL_NAMESPACE
          test_type_1 t1;
          auto e1 = internal::extract_position( t1 );
          static_assert( std::is_same_v< decltype( e1 ), test_type_1 > );
+         (void)e1;
       }
       {
          test_type_2 t2;
          decltype( auto ) e2 = internal::extract_position( t2 );
          static_assert( std::is_same_v< decltype( e2 ), test_type_1 > );
+         (void)e2;
       }
       {
          test_type_3 t3;
          decltype( auto ) e3 = internal::extract_position( t3 );
          static_assert( std::is_same_v< decltype( e3 ), const test_type_1& > );
+         (void)e3;
       }
       {
          test_type_5 t5;
          decltype( auto ) e5 = internal::extract_position( t5 );
          static_assert( std::is_same_v< decltype( e5 ), test_type_1 > );
+         (void)e5;
       }
       {
          test_type_7 t7;
          decltype( auto ) e7 = internal::extract_position( t7 );
          static_assert( std::is_same_v< decltype( e7 ), const test_type_1& > );
+         (void)e7;
       }
    }
 
diff --git a/src/test/pegtl/internal_get_eol_rule_char.cpp b/src/test/pegtl/internal_get_eol_rule_char.cpp
index 7c5379b5..d6acecca 100644
--- a/src/test/pegtl/internal_get_eol_rule_char.cpp
+++ b/src/test/pegtl/internal_get_eol_rule_char.cpp
@@ -14,29 +14,29 @@ using namespace TAO_PEGTL_NAMESPACE;
 
 int main()
 {
-   static_assert( internal::get_eol_rule_char_v< void > == false );
+   static_assert( !internal::get_eol_rule_char_v< void > );
    static_assert( std::is_same_v< decltype( internal::get_eol_rule_char_v< void > ), const bool > );
-   static_assert( internal::get_eol_rule_char_v< char > == false );
+   static_assert( !internal::get_eol_rule_char_v< char > );
    static_assert( std::is_same_v< decltype( internal::get_eol_rule_char_v< char > ), const bool > );
-   static_assert( internal::get_eol_rule_char_v< std::string > == false );
+   static_assert( !internal::get_eol_rule_char_v< std::string > );
    static_assert( std::is_same_v< decltype( internal::get_eol_rule_char_v< std::string > ), const bool > );
 
    static_assert( internal::get_eol_rule_char_v< ascii::lf > == '\n' );
    static_assert( std::is_same_v< decltype( internal::get_eol_rule_char_v< ascii::lf > ), const char > );
-   static_assert( internal::get_eol_rule_char_v< ascii::cr_lf > == false );
+   static_assert( !internal::get_eol_rule_char_v< ascii::cr_lf > );
    static_assert( std::is_same_v< decltype( internal::get_eol_rule_char_v< ascii::cr_lf > ), const bool > );
 
    static_assert( internal::get_eol_rule_char_v< utf8::lf > == '\n' );
    static_assert( std::is_same_v< decltype( internal::get_eol_rule_char_v< utf8::lf > ), const char > );
-   static_assert( internal::get_eol_rule_char_v< utf8::cr_lf > == false );
+   static_assert( !internal::get_eol_rule_char_v< utf8::cr_lf > );
    static_assert( std::is_same_v< decltype( internal::get_eol_rule_char_v< utf8::cr_lf > ), const bool > );
 
    static_assert( internal::get_eol_rule_char_v< utf32::lf > == '\n' );
    static_assert( std::is_same_v< decltype( internal::get_eol_rule_char_v< utf32::lf > ), const char32_t > );
-   static_assert( internal::get_eol_rule_char_v< utf32::cr_lf > == false );
+   static_assert( !internal::get_eol_rule_char_v< utf32::cr_lf > );
    static_assert( std::is_same_v< decltype( internal::get_eol_rule_char_v< utf32::cr_lf > ), const bool > );
 
-   static_assert( internal::get_eol_rule_char_v< ascii::digit > == false );
+   static_assert( !internal::get_eol_rule_char_v< ascii::digit > );
    static_assert( std::is_same_v< decltype( internal::get_eol_rule_char_v< ascii::digit > ), const bool > );
 
    return 0;
diff --git a/src/test/pegtl/internal_peek_ascii.cpp b/src/test/pegtl/internal_peek_ascii.cpp
index 9f1ea1e4..bed7db11 100644
--- a/src/test/pegtl/internal_peek_ascii.cpp
+++ b/src/test/pegtl/internal_peek_ascii.cpp
@@ -51,17 +51,17 @@ namespace TAO_PEGTL_NAMESPACE
          {
             const auto pair = peek7::peek( in, 3 );
             TAO_PEGTL_TEST_ASSERT( !pair );
-            TAO_PEGTL_TEST_ASSERT( pair.size() == 0 );
+            TAO_PEGTL_TEST_ASSERT( pair.empty() );
          }
          {
             const auto pair = peek7::peek( in, 4 );
             TAO_PEGTL_TEST_ASSERT( !pair );
-            TAO_PEGTL_TEST_ASSERT( pair.size() == 0 );
+            TAO_PEGTL_TEST_ASSERT( pair.empty() );
          }
          {
             const auto pair = peek7::peek( in, 5 );
             TAO_PEGTL_TEST_ASSERT( !pair );
-            TAO_PEGTL_TEST_ASSERT( pair.size() == 0 );
+            TAO_PEGTL_TEST_ASSERT( pair.empty() );
          }
       }
    }
diff --git a/src/test/pegtl/internal_peek_member.cpp b/src/test/pegtl/internal_peek_member.cpp
index 51eb69cf..d10ea908 100644
--- a/src/test/pegtl/internal_peek_member.cpp
+++ b/src/test/pegtl/internal_peek_member.cpp
@@ -29,7 +29,7 @@ namespace TAO_PEGTL_NAMESPACE
       int* const global3 = &the_integer;
       const int* const global4 = &the_integer;
 
-      [[nodiscard]] int method1() const noexcept
+      [[nodiscard]] int method1() const noexcept  // NOLINT(readability-convert-member-functions-to-static)
       {
          return 503;
       }
diff --git a/src/test/pegtl/internal_stream_to_string.cpp b/src/test/pegtl/internal_stream_to_string.cpp
index 1e32d7bd..1ca55ac3 100644
--- a/src/test/pegtl/internal_stream_to_string.cpp
+++ b/src/test/pegtl/internal_stream_to_string.cpp
@@ -10,7 +10,7 @@ namespace TAO_PEGTL_NAMESPACE
 {
    void unit_test()
    {
-      TAO_PEGTL_TEST_ASSERT( internal::stream_to_string() == "" );
+      TAO_PEGTL_TEST_ASSERT( internal::stream_to_string().empty() );
       TAO_PEGTL_TEST_ASSERT( internal::stream_to_string( "foo" ) == "foo" );
       TAO_PEGTL_TEST_ASSERT( internal::stream_to_string( "foo", 42, "bar" ) == "foo42bar" );
    }
diff --git a/src/test/pegtl/internal_text_inputs.cpp b/src/test/pegtl/internal_text_inputs.cpp
index b35be8a0..cb20e91b 100644
--- a/src/test/pegtl/internal_text_inputs.cpp
+++ b/src/test/pegtl/internal_text_inputs.cpp
@@ -140,6 +140,10 @@ namespace TAO_PEGTL_NAMESPACE
          TAO_PEGTL_TEST_ASSERT( test::equal( in.current_position(), 2, 2, 3 ) );
          TAO_PEGTL_TEST_ASSERT( in.direct_position() == in.current_position() );
       }
+   }
+
+   void test_02_text()
+   {
       using input_1 = text_view_input< ascii::lf >;
       {
          input_1 in( "" );
@@ -238,6 +242,7 @@ namespace TAO_PEGTL_NAMESPACE
    void unit_test()
    {
       test_01_text();
+      test_02_text();
    }
 
 }  // namespace TAO_PEGTL_NAMESPACE
diff --git a/src/test/pegtl/internal_unwind_guard.cpp b/src/test/pegtl/internal_unwind_guard.cpp
index bd4e7a0c..ef52e978 100644
--- a/src/test/pegtl/internal_unwind_guard.cpp
+++ b/src/test/pegtl/internal_unwind_guard.cpp
@@ -25,7 +25,7 @@ namespace TAO_PEGTL_NAMESPACE
    void test2()
    {
       int i = 1;
-      internal::unwind_guard( [ & ]() { i = 2; } );  // Anonymous object.
+      internal::unwind_guard( [ & ]() { i = 2; } );  // NOLINT(bugprone-unused-raii)
       TAO_PEGTL_TEST_ASSERT( i == 2 );
    }
 
diff --git a/src/test/pegtl/rule_nested.cpp b/src/test/pegtl/rule_nested.cpp
index 2d980cfa..56edc23f 100644
--- a/src/test/pegtl/rule_nested.cpp
+++ b/src/test/pegtl/rule_nested.cpp
@@ -33,7 +33,9 @@ namespace TAO_PEGTL_NAMESPACE
 
    void test_success()
    {
-      outer_input in( { { "foo", 1 } } );
+      outer_input in( {
+         {"foo", 1}
+      } );
       TAO_PEGTL_TEST_ASSERT( in.size() == 1 );
       const auto b = parse< outer_grammar >( in );
       TAO_PEGTL_TEST_ASSERT( b );
@@ -41,7 +43,9 @@ namespace TAO_PEGTL_NAMESPACE
 
    void test_failure1()
    {
-      outer_input in( { { "bar", 1 } } );
+      outer_input in( {
+         {"bar", 1}
+      } );
       TAO_PEGTL_TEST_ASSERT( in.size() == 1 );
       const auto b = parse< outer_grammar >( in );
       TAO_PEGTL_TEST_ASSERT( !b );
@@ -57,7 +61,10 @@ namespace TAO_PEGTL_NAMESPACE
 
    void test_failure3()
    {
-      outer_input in( { { "foo", 1 }, { "foo", 1 } } );
+      outer_input in( {
+         {"foo",  1},
+         { "foo", 1}
+      } );
       TAO_PEGTL_TEST_ASSERT( in.size() == 2 );
       const auto b = parse< outer_grammar >( in );
       TAO_PEGTL_TEST_ASSERT( !b );