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* [PATCH] libcpp: Add -Winvalid-utf8 warning [PR106655]
@ 2022-08-29  8:15 Jakub Jelinek
  2022-08-29 21:15 ` Jason Merrill
  0 siblings, 1 reply; 11+ messages in thread
From: Jakub Jelinek @ 2022-08-29  8:15 UTC (permalink / raw)
  To: Jason Merrill; +Cc: gcc-patches

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Hi!

The following patch introduces a new warning - -Winvalid-utf8 similarly
to what clang now has - to diagnose invalid UTF-8 byte sequences in
comments.  In identifiers and in string literals it should be diagnosed
already but comment content hasn't been really verified.

I'm not sure if this is enough to say P2295R6 is implemented or not.

The problem is that in the most common case, people don't use
-finput-charset= option and the sources often are UTF-8, but sometimes
could be some ASCII compatible single byte encoding where non-ASCII
characters only appear in comments.  So having the warning off by default
is IMO desirable.  Now, if people use explicit -finput-charset=UTF-8,
perhaps we could make the warning on by default for C++23 and use pedwarn
instead of warning, because then the user told us explicitly that the source
is UTF-8.  From the paper I understood one of the implementation options
is to claim that the implementation supports 2 encodings, UTF-8 and UTF-8
like encodings where invalid UTF-8 characters in comments are replaced say
by spaces, where the latter could be the default and the former only
used if -finput-charset=UTF-8 -Werror=invalid-utf8 options are used.

Thoughts on this?

2022-08-29  Jakub Jelinek  <jakub@redhat.com>

	PR c++/106655
libcpp/
	* include/cpplib.h (struct cpp_options): Implement C++23
	P2295R6 - Support for UTF-8 as a portable source file encoding.
	Add cpp_warn_invalid_utf8 field.
	(enum cpp_warning_reason): Add CPP_W_INVALID_UTF8 enumerator.
	* init.cc (cpp_create_reader): Initialize cpp_warn_invalid_utf8.
	* lex.cc (utf8_continuation): New const variable.
	(utf8_signifier): Move earlier in the file.
	(_cpp_warn_invalid_utf8): New function.
	(_cpp_skip_block_comment): Handle -Winvalid-utf8 warning.
	(skip_line_comment): Likewise.
gcc/
	* doc/invoke.texi (-Winvalid-utf8): Document it.
gcc/c-family/
	* c.opt (-Winvalid-utf8): New warning.
gcc/testsuite/
	* c-c++-common/cpp/Winvalid-utf8-1.c: New test.

--- libcpp/include/cpplib.h.jj	2022-08-25 14:25:23.866912426 +0200
+++ libcpp/include/cpplib.h	2022-08-27 12:17:55.185022807 +0200
@@ -560,6 +560,9 @@ struct cpp_options
      cpp_bidirectional_level.  */
   unsigned char cpp_warn_bidirectional;
 
+  /* True if libcpp should warn about invalid UTF-8 characters in comments.  */
+  bool cpp_warn_invalid_utf8;
+
   /* Dependency generation.  */
   struct
   {
@@ -666,7 +669,8 @@ enum cpp_warning_reason {
   CPP_W_CXX11_COMPAT,
   CPP_W_CXX20_COMPAT,
   CPP_W_EXPANSION_TO_DEFINED,
-  CPP_W_BIDIRECTIONAL
+  CPP_W_BIDIRECTIONAL,
+  CPP_W_INVALID_UTF8
 };
 
 /* Callback for header lookup for HEADER, which is the name of a
--- libcpp/init.cc.jj	2022-08-24 09:55:44.571876638 +0200
+++ libcpp/init.cc	2022-08-27 12:18:54.559246323 +0200
@@ -227,6 +227,7 @@ cpp_create_reader (enum c_lang lang, cpp
   CPP_OPTION (pfile, ext_numeric_literals) = 1;
   CPP_OPTION (pfile, warn_date_time) = 0;
   CPP_OPTION (pfile, cpp_warn_bidirectional) = bidirectional_unpaired;
+  CPP_OPTION (pfile, cpp_warn_invalid_utf8) = 0;
 
   /* Default CPP arithmetic to something sensible for the host for the
      benefit of dumb users like fix-header.  */
--- libcpp/lex.cc.jj	2022-08-26 09:24:12.089615949 +0200
+++ libcpp/lex.cc	2022-08-27 13:43:40.560769087 +0200
@@ -1704,6 +1704,59 @@ maybe_warn_bidi_on_char (cpp_reader *pfi
   bidi::on_char (kind, ucn_p, loc);
 }
 
+static const cppchar_t utf8_continuation = 0x80;
+static const cppchar_t utf8_signifier = 0xC0;
+
+/* Emit -Winvalid-utf8 warning on invalid UTF-8 character starting
+   at PFILE->buffer->cur.  Return a pointer after the diagnosed
+   invalid character.  */
+
+static const uchar *
+_cpp_warn_invalid_utf8 (cpp_reader *pfile)
+{
+  cpp_buffer *buffer = pfile->buffer;
+  const uchar *cur = buffer->cur;
+
+  if (cur[0] < utf8_signifier
+      || cur[1] < utf8_continuation || cur[1] >= utf8_signifier)
+    {
+      cpp_warning_with_line (pfile, CPP_W_INVALID_UTF8,
+			     pfile->line_table->highest_line,
+			     CPP_BUF_COL (buffer),
+			     "invalid UTF-8 character <%x> in comment",
+			     cur[0]);
+      return cur + 1;
+    }
+  else if (cur[2] < utf8_continuation || cur[2] >= utf8_signifier)
+    {
+      cpp_warning_with_line (pfile, CPP_W_INVALID_UTF8,
+			     pfile->line_table->highest_line,
+			     CPP_BUF_COL (buffer),
+			     "invalid UTF-8 character <%x><%x> in comment",
+			     cur[0], cur[1]);
+      return cur + 2;
+    }
+  else if (cur[3] < utf8_continuation || cur[3] >= utf8_signifier)
+    {
+      cpp_warning_with_line (pfile, CPP_W_INVALID_UTF8,
+			     pfile->line_table->highest_line,
+			     CPP_BUF_COL (buffer),
+			     "invalid UTF-8 character <%x><%x><%x> in comment",
+			     cur[0], cur[1], cur[2]);
+      return cur + 3;
+    }
+  else
+    {
+      cpp_warning_with_line (pfile, CPP_W_INVALID_UTF8,
+			     pfile->line_table->highest_line,
+			     CPP_BUF_COL (buffer),
+			     "invalid UTF-8 character "
+			     "<%x><%x><%x><%x> in comment",
+			     cur[0], cur[1], cur[2], cur[3]);
+      return cur + 4;
+    }
+}
+
 /* Skip a C-style block comment.  We find the end of the comment by
    seeing if an asterisk is before every '/' we encounter.  Returns
    nonzero if comment terminated by EOF, zero otherwise.
@@ -1716,6 +1769,8 @@ _cpp_skip_block_comment (cpp_reader *pfi
   const uchar *cur = buffer->cur;
   uchar c;
   const bool warn_bidi_p = pfile->warn_bidi_p ();
+  const bool warn_invalid_utf8_p = CPP_OPTION (pfile, cpp_warn_invalid_utf8);
+  const bool warn_bidi_or_invalid_utf8_p = warn_bidi_p | warn_invalid_utf8_p;
 
   cur++;
   if (*cur == '/')
@@ -1765,13 +1820,32 @@ _cpp_skip_block_comment (cpp_reader *pfi
 
 	  cur = buffer->cur;
 	}
-      /* If this is a beginning of a UTF-8 encoding, it might be
-	 a bidirectional control character.  */
-      else if (__builtin_expect (c == bidi::utf8_start, 0) && warn_bidi_p)
-	{
-	  location_t loc;
-	  bidi::kind kind = get_bidi_utf8 (pfile, cur - 1, &loc);
-	  maybe_warn_bidi_on_char (pfile, kind, /*ucn_p=*/false, loc);
+      else if (__builtin_expect (c >= utf8_continuation, 0)
+	       && warn_bidi_or_invalid_utf8_p)
+	{
+	  /* If this is a beginning of a UTF-8 encoding, it might be
+	     a bidirectional control character.  */
+	  if (c == bidi::utf8_start && warn_bidi_p)
+	    {
+	      location_t loc;
+	      bidi::kind kind = get_bidi_utf8 (pfile, cur - 1, &loc);
+	      maybe_warn_bidi_on_char (pfile, kind, /*ucn_p=*/false, loc);
+	    }
+	  if (!warn_invalid_utf8_p)
+	    continue;
+	  if (c >= utf8_signifier)
+	    {
+	      cppchar_t s;
+	      const uchar *pstr = cur - 1;
+	      if (_cpp_valid_utf8 (pfile, &pstr, buffer->rlimit, 0, NULL, &s)
+		  && s <= 0x0010FFFF)
+		{
+		  cur = pstr;
+		  continue;
+		}
+	    }
+	  buffer->cur = cur - 1;
+	  cur = _cpp_warn_invalid_utf8 (pfile);
 	}
     }
 
@@ -1789,11 +1863,13 @@ skip_line_comment (cpp_reader *pfile)
   cpp_buffer *buffer = pfile->buffer;
   location_t orig_line = pfile->line_table->highest_line;
   const bool warn_bidi_p = pfile->warn_bidi_p ();
+  const bool warn_invalid_utf8_p = CPP_OPTION (pfile, cpp_warn_invalid_utf8);
+  const bool warn_bidi_or_invalid_utf8_p = warn_bidi_p | warn_invalid_utf8_p;
 
-  if (!warn_bidi_p)
+  if (!warn_bidi_or_invalid_utf8_p)
     while (*buffer->cur != '\n')
       buffer->cur++;
-  else
+  else if (!warn_invalid_utf8_p)
     {
       while (*buffer->cur != '\n'
 	     && *buffer->cur != bidi::utf8_start)
@@ -1813,6 +1889,38 @@ skip_line_comment (cpp_reader *pfile)
 	  maybe_warn_bidi_on_close (pfile, buffer->cur);
 	}
     }
+  else
+    {
+      while (*buffer->cur != '\n')
+	{
+	  if (*buffer->cur < utf8_continuation)
+	    {
+	      buffer->cur++;
+	      continue;
+	    }
+	  if (__builtin_expect (*buffer->cur == bidi::utf8_start, 0)
+	      && warn_bidi_p)
+	    {
+	      location_t loc;
+	      bidi::kind kind = get_bidi_utf8 (pfile, buffer->cur, &loc);
+	      maybe_warn_bidi_on_char (pfile, kind, /*ucn_p=*/false, loc);
+	    }
+	  if (*buffer->cur >= utf8_signifier)
+	    {
+	      cppchar_t s;
+	      const uchar *pstr = buffer->cur;
+	      if (_cpp_valid_utf8 (pfile, &pstr, buffer->rlimit, 0, NULL, &s)
+		  && s <= 0x0010FFFF)
+		{
+		  buffer->cur = pstr;
+		  continue;
+		}
+	    }
+	  buffer->cur = _cpp_warn_invalid_utf8 (pfile);
+	}
+      if (warn_bidi_p)
+	maybe_warn_bidi_on_close (pfile, buffer->cur);
+    }
 
   _cpp_process_line_notes (pfile, true);
   return orig_line != pfile->line_table->highest_line;
@@ -1919,8 +2027,6 @@ warn_about_normalization (cpp_reader *pf
     }
 }
 
-static const cppchar_t utf8_signifier = 0xC0;
-
 /* Returns TRUE if the sequence starting at buffer->cur is valid in
    an identifier.  FIRST is TRUE if this starts an identifier.  */
 
--- gcc/doc/invoke.texi.jj	2022-08-27 09:14:43.047696028 +0200
+++ gcc/doc/invoke.texi	2022-08-27 14:05:22.417755406 +0200
@@ -365,9 +365,9 @@ Objective-C and Objective-C++ Dialects}.
 -Winfinite-recursion @gol
 -Winit-self  -Winline  -Wno-int-conversion  -Wint-in-bool-context @gol
 -Wno-int-to-pointer-cast  -Wno-invalid-memory-model @gol
--Winvalid-pch  -Wjump-misses-init  -Wlarger-than=@var{byte-size} @gol
--Wlogical-not-parentheses  -Wlogical-op  -Wlong-long @gol
--Wno-lto-type-mismatch -Wmain  -Wmaybe-uninitialized @gol
+-Winvalid-pch  -Winvalid-utf8 -Wjump-misses-init  @gol
+-Wlarger-than=@var{byte-size}  -Wlogical-not-parentheses  -Wlogical-op  @gol
+-Wlong-long  -Wno-lto-type-mismatch -Wmain  -Wmaybe-uninitialized @gol
 -Wmemset-elt-size  -Wmemset-transposed-args @gol
 -Wmisleading-indentation  -Wmissing-attributes  -Wmissing-braces @gol
 -Wmissing-field-initializers  -Wmissing-format-attribute @gol
@@ -9569,6 +9569,11 @@ different size.
 Warn if a precompiled header (@pxref{Precompiled Headers}) is found in
 the search path but cannot be used.
 
+@item -Winvalid-utf8
+@opindex Winvalid-utf8
+@opindex Wno-invalid-utf8
+Warn if an invalid UTF-8 character is inside of a comment.
+
 @item -Wlong-long
 @opindex Wlong-long
 @opindex Wno-long-long
--- gcc/c-family/c.opt.jj	2022-08-27 09:14:43.036696173 +0200
+++ gcc/c-family/c.opt	2022-08-27 14:03:06.328534617 +0200
@@ -821,6 +821,10 @@ Winvalid-pch
 C ObjC C++ ObjC++ CPP(warn_invalid_pch) CppReason(CPP_W_INVALID_PCH) Var(cpp_warn_invalid_pch) Init(0) Warning
 Warn about PCH files that are found but not used.
 
+Winvalid-utf8
+C objC C++ ObjC++ CPP(cpp_warn_invalid_utf8) CppReason(CPP_W_INVALID_UTF8) Var(warn_invalid_utf8) Init(0) Warning
+Warn about invalid UTF-8 characters in comments.
+
 Wjump-misses-init
 C ObjC Var(warn_jump_misses_init) Warning LangEnabledby(C ObjC,Wc++-compat)
 Warn when a jump misses a variable initialization.
--- gcc/testsuite/c-c++-common/cpp/Winvalid-utf8-1.c.jj	2022-08-27 14:01:51.115517571 +0200
+++ gcc/testsuite/c-c++-common/cpp/Winvalid-utf8-1.c	2022-08-27 14:33:21.466802817 +0200
@@ -0,0 +1,39 @@
+// P2295R6 - Support for UTF-8 as a portable source file encoding
+// This test intentionally contains various byte sequences which are not valid UTF-8
+// { dg-do preprocess }
+// { dg-options "-finput-charset=UTF-8 -Winvalid-utf8" }
+
+// a€߿ࠀ퟿𐀀􏿿a		{ dg-bogus "invalid UTF-8 character" }
+// a�a					{ dg-warning "invalid UTF-8 character <80> in comment" }
+// a�a					{ dg-warning "invalid UTF-8 character <bf> in comment" }
+// a�a					{ dg-warning "invalid UTF-8 character <c0> in comment" }
+// a�a					{ dg-warning "invalid UTF-8 character <c1> in comment" }
+// a�a					{ dg-warning "invalid UTF-8 character <f5> in comment" }
+// a�a					{ dg-warning "invalid UTF-8 character <ff> in comment" }
+// a�a					{ dg-warning "invalid UTF-8 character <c2> in comment" }
+// a�a					{ dg-warning "invalid UTF-8 character <e0> in comment" }
+// a���a				{ dg-warning "invalid UTF-8 character <e0><80><bf> in comment" }
+// a���a				{ dg-warning "invalid UTF-8 character <e0><9f><80> in comment" }
+// a��a					{ dg-warning "invalid UTF-8 character <e0><bf> in comment" }
+// a��a					{ dg-warning "invalid UTF-8 character <ec><80> in comment" }
+// a���a				{ dg-warning "invalid UTF-8 character <ed><a0><80> in comment" }
+// a����a				{ dg-warning "invalid UTF-8 character <f0><80><80><80> in comment" }
+// a����a				{ dg-warning "invalid UTF-8 character <f0><8f><bf><bf> in comment" }
+// a����a				{ dg-warning "invalid UTF-8 character <f4><90><80><80> in comment" }
+/* a€߿ࠀ퟿𐀀􏿿a		{ dg-bogus "invalid UTF-8 character" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <80> in comment" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <bf> in comment" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <c0> in comment" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <c1> in comment" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <f5> in comment" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <ff> in comment" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <c2> in comment" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <e0> in comment" } */
+/* a���a				{ dg-warning "invalid UTF-8 character <e0><80><bf> in comment" } */
+/* a���a				{ dg-warning "invalid UTF-8 character <e0><9f><80> in comment" } */
+/* a��a					{ dg-warning "invalid UTF-8 character <e0><bf> in comment" } */
+/* a��a					{ dg-warning "invalid UTF-8 character <ec><80> in comment" } */
+/* a���a				{ dg-warning "invalid UTF-8 character <ed><a0><80> in comment" } */
+/* a����a				{ dg-warning "invalid UTF-8 character <f0><80><80><80> in comment" } */
+/* a����a				{ dg-warning "invalid UTF-8 character <f0><8f><bf><bf> in comment" } */
+/* a����a				{ dg-warning "invalid UTF-8 character <f4><90><80><80> in comment" } */

	Jakub


^ permalink raw reply	[flat|nested] 11+ messages in thread
end of thread, other threads:[~2022-08-31 14:24 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-08-29  8:15 [PATCH] libcpp: Add -Winvalid-utf8 warning [PR106655] Jakub Jelinek
2022-08-29 21:15 ` Jason Merrill
2022-08-29 21:35   ` Jakub Jelinek
2022-08-29 21:54     ` Jakub Jelinek
2022-08-30  3:31     ` Jason Merrill
2022-08-30 15:20       ` [PATCH] libcpp, v2: " Jakub Jelinek
2022-08-30 21:51         ` Jason Merrill
2022-08-31 11:14           ` [PATCH] libcpp, v3: " Jakub Jelinek
2022-08-31 13:55             ` Jason Merrill
2022-08-31 14:15               ` [PATCH] libcpp, v4: " Jakub Jelinek
2022-08-31 14:24                 ` Jason Merrill

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