libcpp: Add -Winvalid-utf8 warning [PR106655]

The following patch introduces a new warning - -Winvalid-utf8 similarly
to what clang now has - to diagnose invalid UTF-8 byte sequences in
comments, but not just in those, but also in string/character literals
and outside of them.

The warning is on by default when explicit -finput-charset=UTF-8 is
used and C++23 compilation is requested and if -{,W}pedantic or
-pedantic-errors it is actually a pedwarn.

The reason it is on by default only for -finput-charset=UTF-8 is
that 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.  The C++23 pedantic mode for when the source code
is UTF-8 is -std=c++23 -pedantic-errors -finput-charset=UTF-8.

2022-09-01  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 and cpp_input_charset_explicit fields.
	(enum cpp_warning_reason): Add CPP_W_INVALID_UTF8 enumerator.
	* init.cc (cpp_create_reader): Initialize cpp_warn_invalid_utf8
	and cpp_input_charset_explicit.
	* charset.cc (_cpp_valid_utf8): Adjust function comment.
	* lex.cc (UCS_LIMIT): Define.
	(utf8_continuation): New const variable.
	(utf8_signifier): Move earlier in the file.
	(_cpp_warn_invalid_utf8, _cpp_handle_multibyte_utf8): New functions.
	(_cpp_skip_block_comment): Handle -Winvalid-utf8 warning.
	(skip_line_comment): Likewise.
	(lex_raw_string, lex_string): Likewise.
	(_cpp_lex_direct): Likewise.
gcc/
	* doc/invoke.texi (-Winvalid-utf8): Document it.
gcc/c-family/
	* c.opt (-Winvalid-utf8): New warning.
	* c-opts.cc (c_common_handle_option) <case OPT_finput_charset_>:
	Set cpp_opts->cpp_input_charset_explicit.
	(c_common_post_options): If -finput-charset=UTF-8 is explicit
	in C++23, enable -Winvalid-utf8 by default and if -pedantic
	or -pedantic-errors, make it a pedwarn.
gcc/testsuite/
	* c-c++-common/cpp/Winvalid-utf8-1.c: New test.
	* c-c++-common/cpp/Winvalid-utf8-2.c: New test.
	* c-c++-common/cpp/Winvalid-utf8-3.c: New test.
	* g++.dg/cpp23/Winvalid-utf8-1.C: New test.
	* g++.dg/cpp23/Winvalid-utf8-2.C: New test.
	* g++.dg/cpp23/Winvalid-utf8-3.C: New test.
	* g++.dg/cpp23/Winvalid-utf8-4.C: New test.
	* g++.dg/cpp23/Winvalid-utf8-5.C: New test.
	* g++.dg/cpp23/Winvalid-utf8-6.C: New test.
	* g++.dg/cpp23/Winvalid-utf8-7.C: New test.
	* g++.dg/cpp23/Winvalid-utf8-8.C: New test.
	* g++.dg/cpp23/Winvalid-utf8-9.C: New test.
	* g++.dg/cpp23/Winvalid-utf8-10.C: New test.
	* g++.dg/cpp23/Winvalid-utf8-11.C: New test.
	* g++.dg/cpp23/Winvalid-utf8-12.C: New test.

18 files changed, 776 insertions, 3 deletions

diff --git a/gcc/c-family/c-opts.cc b/gcc/c-family/c-opts.cc
index 337a524..babaa2f 100644
--- a/gcc/c-family/c-opts.cc
+++ b/gcc/c-family/c-opts.cc
@@ -534,6 +534,7 @@ c_common_handle_option (size_t scode, const char *arg, HOST_WIDE_INT value,
 
     case OPT_finput_charset_:
       cpp_opts->input_charset = arg;
+      cpp_opts->cpp_input_charset_explicit = 1;
       break;
 
     case OPT_ftemplate_depth_:
@@ -1152,6 +1153,17 @@ c_common_post_options (const char **pfilename)
     lang_hooks.preprocess_options (parse_in);
   cpp_post_options (parse_in);
   init_global_opts_from_cpp (&global_options, cpp_get_options (parse_in));
+  /* For C++23 and explicit -finput-charset=UTF-8, turn on -Winvalid-utf8
+     by default and make it a pedwarn unless -Wno-invalid-utf8.  */
+  if (cxx_dialect >= cxx23
+      && cpp_opts->cpp_input_charset_explicit
+      && strcmp (cpp_opts->input_charset, "UTF-8") == 0
+      && (cpp_opts->cpp_warn_invalid_utf8
+	  || !global_options_set.x_warn_invalid_utf8))
+    {
+      global_options.x_warn_invalid_utf8 = 1;
+      cpp_opts->cpp_warn_invalid_utf8 = cpp_opts->cpp_pedantic ? 2 : 1;
+    }
 
   /* Let diagnostics infrastructure know how to convert input files the same
      way libcpp will do it, namely using the configured input charset and
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index f776efd..ff6fe86 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -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.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index e5eb525..8def6ba 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -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 +9569,13 @@ 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 found.
+This warning is on by default for C++23 if @option{-finput-charset=UTF-8}
+is used and turned into error with @option{-pedantic-errors}.
+
 @item -Wlong-long
 @opindex Wlong-long
 @opindex Wno-long-long
diff --git a/gcc/testsuite/c-c++-common/cpp/Winvalid-utf8-1.c b/gcc/testsuite/c-c++-common/cpp/Winvalid-utf8-1.c
new file mode 100644
index 0000000..0d5a6a7
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Winvalid-utf8-1.c
@@ -0,0 +1,43 @@
+// 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>" }
+// a�a					{ dg-warning "invalid UTF-8 character <bf>" }
+// a�a					{ dg-warning "invalid UTF-8 character <c0>" }
+// a�a					{ dg-warning "invalid UTF-8 character <c1>" }
+// a�a					{ dg-warning "invalid UTF-8 character <f5>" }
+// a�a					{ dg-warning "invalid UTF-8 character <ff>" }
+// a�a					{ dg-warning "invalid UTF-8 character <c2>" }
+// a�a					{ dg-warning "invalid UTF-8 character <e0>" }
+// a���a				{ dg-warning "invalid UTF-8 character <e0><80><bf>" }
+// a���a				{ dg-warning "invalid UTF-8 character <e0><9f><80>" }
+// a�a					{ dg-warning "invalid UTF-8 character <e0><bf>" }
+// a�a					{ dg-warning "invalid UTF-8 character <ec><80>" }
+// a���a				{ dg-warning "invalid UTF-8 character <ed><a0><80>" }
+// a����a				{ dg-warning "invalid UTF-8 character <f0><80><80><80>" }
+// a����a				{ dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" }
+// a����a				{ dg-warning "invalid UTF-8 character <f4><90><80><80>" }
+// a������a				{ dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" }
+//					{ dg-warning "invalid UTF-8 character <bf>" "" { target *-*-* } .-1 }
+/* a€߿ࠀ퟿𐀀􏿿a		{ dg-bogus "invalid UTF-8 character" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <80>" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <bf>" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <c0>" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <c1>" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <f5>" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <ff>" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <c2>" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <e0>" } */
+/* a���a				{ dg-warning "invalid UTF-8 character <e0><80><bf>" } */
+/* a���a				{ dg-warning "invalid UTF-8 character <e0><9f><80>" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <e0><bf>" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <ec><80>" } */
+/* a���a				{ dg-warning "invalid UTF-8 character <ed><a0><80>" } */
+/* a����a				{ dg-warning "invalid UTF-8 character <f0><80><80><80>" } */
+/* a����a				{ dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" } */
+/* a����a				{ dg-warning "invalid UTF-8 character <f4><90><80><80>" } */
+/* a������a				{ dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" } */
+/*					{ dg-warning "invalid UTF-8 character <bf>" "" { target *-*-* } .-1 } */
diff --git a/gcc/testsuite/c-c++-common/cpp/Winvalid-utf8-2.c b/gcc/testsuite/c-c++-common/cpp/Winvalid-utf8-2.c
new file mode 100644
index 0000000..9ab69e1
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Winvalid-utf8-2.c
@@ -0,0 +1,88 @@
+// 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 { target { c || c++11 } } }
+// { dg-require-effective-target wchar }
+// { dg-options "-finput-charset=UTF-8 -Winvalid-utf8" }
+// { dg-additional-options "-std=gnu99" { target c } }
+
+#ifndef __cplusplus
+#include <wchar.h>
+typedef __CHAR16_TYPE__ char16_t;
+typedef __CHAR32_TYPE__ char32_t;
+#endif
+
+char32_t a = U'�';				// { dg-warning "invalid UTF-8 character <80>" }
+char32_t b = U'�';				// { dg-warning "invalid UTF-8 character <bf>" }
+char32_t c = U'�';				// { dg-warning "invalid UTF-8 character <c0>" }
+char32_t d = U'�';				// { dg-warning "invalid UTF-8 character <c1>" }
+char32_t e = U'�';				// { dg-warning "invalid UTF-8 character <f5>" }
+char32_t f = U'�';				// { dg-warning "invalid UTF-8 character <ff>" }
+char32_t g = U'�';				// { dg-warning "invalid UTF-8 character <c2>" }
+char32_t h = U'�';				// { dg-warning "invalid UTF-8 character <e0>" }
+char32_t i = U'���';				// { dg-warning "invalid UTF-8 character <e0><80><bf>" }
+char32_t j = U'���';				// { dg-warning "invalid UTF-8 character <e0><9f><80>" }
+char32_t k = U'�';				// { dg-warning "invalid UTF-8 character <e0><bf>" }
+char32_t l = U'�';				// { dg-warning "invalid UTF-8 character <ec><80>" }
+char32_t m = U'���';				// { dg-warning "invalid UTF-8 character <ed><a0><80>" }
+char32_t n = U'����';				// { dg-warning "invalid UTF-8 character <f0><80><80><80>" }
+char32_t o = U'����';				// { dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" }
+char32_t p = U'����';				// { dg-warning "invalid UTF-8 character <f4><90><80><80>" }
+char32_t q = U'������';				// { dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" }
+						// { dg-warning "invalid UTF-8 character <bf>" "" { target *-*-* } .-1 }
+const char32_t *A = U"€߿ࠀ퟿𐀀􏿿";	// { dg-bogus "invalid UTF-8 character" }
+const char32_t *B = U"�";			// { dg-warning "invalid UTF-8 character <80>" }
+const char32_t *C = U"�";			// { dg-warning "invalid UTF-8 character <bf>" }
+const char32_t *D = U"�";			// { dg-warning "invalid UTF-8 character <c0>" }
+const char32_t *E = U"�";			// { dg-warning "invalid UTF-8 character <c1>" }
+const char32_t *F = U"�";			// { dg-warning "invalid UTF-8 character <f5>" }
+const char32_t *G = U"�";			// { dg-warning "invalid UTF-8 character <ff>" }
+const char32_t *H = U"�";			// { dg-warning "invalid UTF-8 character <c2>" }
+const char32_t *I = U"�";			// { dg-warning "invalid UTF-8 character <e0>" }
+const char32_t *J = U"���";			// { dg-warning "invalid UTF-8 character <e0><80><bf>" }
+const char32_t *K = U"���";			// { dg-warning "invalid UTF-8 character <e0><9f><80>" }
+const char32_t *L = U"�";			// { dg-warning "invalid UTF-8 character <e0><bf>" }
+const char32_t *M = U"�";			// { dg-warning "invalid UTF-8 character <ec><80>" }
+const char32_t *N = U"���";			// { dg-warning "invalid UTF-8 character <ed><a0><80>" }
+const char32_t *O = U"����";			// { dg-warning "invalid UTF-8 character <f0><80><80><80>" }
+const char32_t *P = U"����";			// { dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" }
+const char32_t *Q = U"����";			// { dg-warning "invalid UTF-8 character <f4><90><80><80>" }
+const char32_t *R = U"������";			// { dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" }
+						// { dg-warning "invalid UTF-8 character <bf>" "" { target *-*-* } .-1 }
+const char32_t *A1 = UR"(€߿ࠀ퟿𐀀􏿿)"; // { dg-bogus "invalid UTF-8 character" }
+const char32_t *B1 = UR"(�)";			// { dg-warning "invalid UTF-8 character <80>" }
+const char32_t *C1 = UR"(�)";			// { dg-warning "invalid UTF-8 character <bf>" }
+const char32_t *D1 = UR"(�)";			// { dg-warning "invalid UTF-8 character <c0>" }
+const char32_t *E1 = UR"(�)";			// { dg-warning "invalid UTF-8 character <c1>" }
+const char32_t *F1 = UR"(�)";			// { dg-warning "invalid UTF-8 character <f5>" }
+const char32_t *G1 = UR"(�)";			// { dg-warning "invalid UTF-8 character <ff>" }
+const char32_t *H1 = UR"(�)";			// { dg-warning "invalid UTF-8 character <c2>" }
+const char32_t *I1 = UR"(�)";			// { dg-warning "invalid UTF-8 character <e0>" }
+const char32_t *J1 = UR"(���)";			// { dg-warning "invalid UTF-8 character <e0><80><bf>" }
+const char32_t *K1 = UR"(���)";			// { dg-warning "invalid UTF-8 character <e0><9f><80>" }
+const char32_t *L1 = UR"(�)";			// { dg-warning "invalid UTF-8 character <e0><bf>" }
+const char32_t *M1 = UR"(�)";			// { dg-warning "invalid UTF-8 character <ec><80>" }
+const char32_t *N1 = UR"(���)";			// { dg-warning "invalid UTF-8 character <ed><a0><80>" }
+const char32_t *O1 = UR"(����)";		// { dg-warning "invalid UTF-8 character <f0><80><80><80>" }
+const char32_t *P1 = UR"(����)";		// { dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" }
+const char32_t *Q1 = UR"(����)";		// { dg-warning "invalid UTF-8 character <f4><90><80><80>" }
+const char32_t *R1 = UR"(������)";		// { dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" }
+						// { dg-warning "invalid UTF-8 character <bf>" "" { target *-*-* } .-1 }
+const char *A2 = u8"€߿ࠀ퟿𐀀􏿿";	// { dg-bogus "invalid UTF-8 character" }
+const char *B2 = u8"�";				// { dg-warning "invalid UTF-8 character <80>" }
+const char *C2 = u8"�";				// { dg-warning "invalid UTF-8 character <bf>" }
+const char *D2 = u8"�";				// { dg-warning "invalid UTF-8 character <c0>" }
+const char *E2 = u8"�";				// { dg-warning "invalid UTF-8 character <c1>" }
+const char *F2 = u8"�";				// { dg-warning "invalid UTF-8 character <f5>" }
+const char *G2 = u8"�";				// { dg-warning "invalid UTF-8 character <ff>" }
+const char *H2 = u8"�";				// { dg-warning "invalid UTF-8 character <c2>" }
+const char *I2 = u8"�";				// { dg-warning "invalid UTF-8 character <e0>" }
+const char *J2 = u8"���";			// { dg-warning "invalid UTF-8 character <e0><80><bf>" }
+const char *K2 = u8"���";			// { dg-warning "invalid UTF-8 character <e0><9f><80>" }
+const char *L2 = u8"�";			// { dg-warning "invalid UTF-8 character <e0><bf>" }
+const char *M2 = u8"�";			// { dg-warning "invalid UTF-8 character <ec><80>" }
+const char *N2 = u8"���";			// { dg-warning "invalid UTF-8 character <ed><a0><80>" }
+const char *O2 = u8"����";			// { dg-warning "invalid UTF-8 character <f0><80><80><80>" }
+const char *P2 = u8"����";			// { dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" }
+const char *Q2 = u8"����";			// { dg-warning "invalid UTF-8 character <f4><90><80><80>" }
+const char *R2 = u8"������";			// { dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" }
+						// { dg-warning "invalid UTF-8 character <bf>" "" { target *-*-* } .-1 }
diff --git a/gcc/testsuite/c-c++-common/cpp/Winvalid-utf8-3.c b/gcc/testsuite/c-c++-common/cpp/Winvalid-utf8-3.c
new file mode 100644
index 0000000..4cb230f
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/Winvalid-utf8-3.c
@@ -0,0 +1,27 @@
+// 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" }
+
+#define I(x)
+I(€߿ࠀ퟿𐀀􏿿)	// { dg-bogus "invalid UTF-8 character" }
+                                // { dg-error "is not valid in an identifier" "" { target c++ } .-1 }
+I(�)				// { dg-warning "invalid UTF-8 character <80>" }
+I(�)				// { dg-warning "invalid UTF-8 character <bf>" }
+I(�)				// { dg-warning "invalid UTF-8 character <c0>" }
+I(�)				// { dg-warning "invalid UTF-8 character <c1>" }
+I(�)				// { dg-warning "invalid UTF-8 character <f5>" }
+I(�)				// { dg-warning "invalid UTF-8 character <ff>" }
+I(�)				// { dg-warning "invalid UTF-8 character <c2>" }
+I(�)				// { dg-warning "invalid UTF-8 character <e0>" }
+I(���)				// { dg-warning "invalid UTF-8 character <e0><80><bf>" }
+I(���)				// { dg-warning "invalid UTF-8 character <e0><9f><80>" }
+I(�)				// { dg-warning "invalid UTF-8 character <e0><bf>" }
+I(�)				// { dg-warning "invalid UTF-8 character <ec><80>" }
+I(���)				// { dg-warning "invalid UTF-8 character <ed><a0><80>" }
+I(����)				// { dg-warning "invalid UTF-8 character <f0><80><80><80>" }
+I(����)				// { dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" }
+I(����)				// { dg-warning "invalid UTF-8 character <f4><90><80><80>" "" { target c } }
+                                // { dg-error "is not valid in an identifier" "" { target c++ } .-1 }
+I(������)			// { dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c } }
+                                // { dg-error "is not valid in an identifier" "" { target c++ } .-1 }
diff --git a/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-1.C b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-1.C
new file mode 100644
index 0000000..95e3827
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-1.C
@@ -0,0 +1,43 @@
+// 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" }
+
+// a€߿ࠀ퟿𐀀􏿿a		{ dg-bogus "invalid UTF-8 character" }
+// a�a					{ dg-warning "invalid UTF-8 character <80>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <c0>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <c1>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <f5>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <ff>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <c2>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <e0>" "" { target c++23 } }
+// a���a				{ dg-warning "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+// a���a				{ dg-warning "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+// a���a				{ dg-warning "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+// a����a				{ dg-warning "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+// a����a				{ dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+// a����a				{ dg-warning "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+// a������a				{ dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+//					{ dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
+/* a€߿ࠀ퟿𐀀􏿿a		{ dg-bogus "invalid UTF-8 character" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <80>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <c0>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <c1>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <f5>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <ff>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <c2>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <e0>" "" { target c++23 } } */
+/* a���a				{ dg-warning "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } } */
+/* a���a				{ dg-warning "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <e0><bf>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <ec><80>" "" { target c++23 } } */
+/* a���a				{ dg-warning "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } } */
+/* a����a				{ dg-warning "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } } */
+/* a����a				{ dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } } */
+/* a����a				{ dg-warning "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } } */
+/* a������a				{ dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } } */
+/*					{ dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } .-1 } */
diff --git a/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-10.C b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-10.C
new file mode 100644
index 0000000..4684b9d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-10.C
@@ -0,0 +1,25 @@
+// 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 -pedantic" }
+
+#define I(x)
+I(€߿ࠀ퟿𐀀􏿿)	// { dg-bogus "invalid UTF-8 character" }
+                                // { dg-error "is not valid in an identifier" "" { target *-*-* } .-1 }
+I(�)				// { dg-warning "invalid UTF-8 character <80>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <c0>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <c1>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <f5>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <ff>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <c2>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <e0>" "" { target c++23 } }
+I(���)				// { dg-warning "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+I(���)				// { dg-warning "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+I(���)				// { dg-warning "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+I(����)				// { dg-warning "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+I(����)				// { dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+I(����)				// { dg-error "is not valid in an identifier" }
+I(������)			// { dg-error "is not valid in an identifier" }
diff --git a/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-11.C b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-11.C
new file mode 100644
index 0000000..85f04bf
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-11.C
@@ -0,0 +1,25 @@
+// 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 -pedantic-errors" }
+
+#define I(x)
+I(€߿ࠀ퟿𐀀􏿿)	// { dg-bogus "invalid UTF-8 character" }
+                                // { dg-error "is not valid in an identifier" "" { target *-*-* } .-1 }
+I(�)				// { dg-error "invalid UTF-8 character <80>" "" { target c++23 } }
+I(�)				// { dg-error "invalid UTF-8 character <bf>" "" { target c++23 } }
+I(�)				// { dg-error "invalid UTF-8 character <c0>" "" { target c++23 } }
+I(�)				// { dg-error "invalid UTF-8 character <c1>" "" { target c++23 } }
+I(�)				// { dg-error "invalid UTF-8 character <f5>" "" { target c++23 } }
+I(�)				// { dg-error "invalid UTF-8 character <ff>" "" { target c++23 } }
+I(�)				// { dg-error "invalid UTF-8 character <c2>" "" { target c++23 } }
+I(�)				// { dg-error "invalid UTF-8 character <e0>" "" { target c++23 } }
+I(���)				// { dg-error "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+I(���)				// { dg-error "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+I(�)				// { dg-error "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+I(�)				// { dg-error "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+I(���)				// { dg-error "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+I(����)				// { dg-error "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+I(����)				// { dg-error "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+I(����)				// { dg-error "is not valid in an identifier" }
+I(������)			// { dg-error "is not valid in an identifier" }
diff --git a/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-12.C b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-12.C
new file mode 100644
index 0000000..6a4091f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-12.C
@@ -0,0 +1,25 @@
+// 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 -pedantic-errors -Wno-invalid-utf8" }
+
+#define I(x)
+I(€߿ࠀ퟿𐀀􏿿)	// { dg-bogus "invalid UTF-8 character" }
+                                // { dg-error "is not valid in an identifier" "" { target *-*-* } .-1 }
+I(�)				// { dg-bogus "invalid UTF-8 character <80>" }
+I(�)				// { dg-bogus "invalid UTF-8 character <bf>" }
+I(�)				// { dg-bogus "invalid UTF-8 character <c0>" }
+I(�)				// { dg-bogus "invalid UTF-8 character <c1>" }
+I(�)				// { dg-bogus "invalid UTF-8 character <f5>" }
+I(�)				// { dg-bogus "invalid UTF-8 character <ff>" }
+I(�)				// { dg-bogus "invalid UTF-8 character <c2>" }
+I(�)				// { dg-bogus "invalid UTF-8 character <e0>" }
+I(���)				// { dg-bogus "invalid UTF-8 character <e0><80><bf>" }
+I(���)				// { dg-bogus "invalid UTF-8 character <e0><9f><80>" }
+I(�)				// { dg-bogus "invalid UTF-8 character <e0><bf>" }
+I(�)				// { dg-bogus "invalid UTF-8 character <ec><80>" }
+I(���)				// { dg-bogus "invalid UTF-8 character <ed><a0><80>" }
+I(����)				// { dg-bogus "invalid UTF-8 character <f0><80><80><80>" }
+I(����)				// { dg-bogus "invalid UTF-8 character <f0><8f><bf><bf>" }
+I(����)				// { dg-error "is not valid in an identifier" }
+I(������)			// { dg-error "is not valid in an identifier" }
diff --git a/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-2.C b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-2.C
new file mode 100644
index 0000000..70ab8e5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-2.C
@@ -0,0 +1,43 @@
+// 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 -pedantic" }
+
+// a€߿ࠀ퟿𐀀􏿿a		{ dg-bogus "invalid UTF-8 character" }
+// a�a					{ dg-warning "invalid UTF-8 character <80>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <c0>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <c1>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <f5>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <ff>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <c2>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <e0>" "" { target c++23 } }
+// a���a				{ dg-warning "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+// a���a				{ dg-warning "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+// a�a					{ dg-warning "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+// a���a				{ dg-warning "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+// a����a				{ dg-warning "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+// a����a				{ dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+// a����a				{ dg-warning "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+// a������a				{ dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+//					{ dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
+/* a€߿ࠀ퟿𐀀􏿿a		{ dg-bogus "invalid UTF-8 character" } */
+/* a�a					{ dg-warning "invalid UTF-8 character <80>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <c0>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <c1>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <f5>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <ff>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <c2>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <e0>" "" { target c++23 } } */
+/* a���a				{ dg-warning "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } } */
+/* a���a				{ dg-warning "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <e0><bf>" "" { target c++23 } } */
+/* a�a					{ dg-warning "invalid UTF-8 character <ec><80>" "" { target c++23 } } */
+/* a���a				{ dg-warning "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } } */
+/* a����a				{ dg-warning "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } } */
+/* a����a				{ dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } } */
+/* a����a				{ dg-warning "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } } */
+/* a������a				{ dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } } */
+/*					{ dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } .-1 } */
diff --git a/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-3.C b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-3.C
new file mode 100644
index 0000000..c0f748b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-3.C
@@ -0,0 +1,43 @@
+// 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 -pedantic-errors" }
+
+// a€߿ࠀ퟿𐀀􏿿a		{ dg-bogus "invalid UTF-8 character" }
+// a�a					{ dg-error "invalid UTF-8 character <80>" "" { target c++23 } }
+// a�a					{ dg-error "invalid UTF-8 character <bf>" "" { target c++23 } }
+// a�a					{ dg-error "invalid UTF-8 character <c0>" "" { target c++23 } }
+// a�a					{ dg-error "invalid UTF-8 character <c1>" "" { target c++23 } }
+// a�a					{ dg-error "invalid UTF-8 character <f5>" "" { target c++23 } }
+// a�a					{ dg-error "invalid UTF-8 character <ff>" "" { target c++23 } }
+// a�a					{ dg-error "invalid UTF-8 character <c2>" "" { target c++23 } }
+// a�a					{ dg-error "invalid UTF-8 character <e0>" "" { target c++23 } }
+// a���a				{ dg-error "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+// a���a				{ dg-error "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+// a�a					{ dg-error "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+// a�a					{ dg-error "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+// a���a				{ dg-error "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+// a����a				{ dg-error "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+// a����a				{ dg-error "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+// a����a				{ dg-error "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+// a������a				{ dg-error "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+//					{ dg-error "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
+/* a€߿ࠀ퟿𐀀􏿿a		{ dg-bogus "invalid UTF-8 character" } */
+/* a�a					{ dg-error "invalid UTF-8 character <80>" "" { target c++23 } } */
+/* a�a					{ dg-error "invalid UTF-8 character <bf>" "" { target c++23 } } */
+/* a�a					{ dg-error "invalid UTF-8 character <c0>" "" { target c++23 } } */
+/* a�a					{ dg-error "invalid UTF-8 character <c1>" "" { target c++23 } } */
+/* a�a					{ dg-error "invalid UTF-8 character <f5>" "" { target c++23 } } */
+/* a�a					{ dg-error "invalid UTF-8 character <ff>" "" { target c++23 } } */
+/* a�a					{ dg-error "invalid UTF-8 character <c2>" "" { target c++23 } } */
+/* a�a					{ dg-error "invalid UTF-8 character <e0>" "" { target c++23 } } */
+/* a���a				{ dg-error "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } } */
+/* a���a				{ dg-error "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } } */
+/* a�a					{ dg-error "invalid UTF-8 character <e0><bf>" "" { target c++23 } } */
+/* a�a					{ dg-error "invalid UTF-8 character <ec><80>" "" { target c++23 } } */
+/* a���a				{ dg-error "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } } */
+/* a����a				{ dg-error "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } } */
+/* a����a				{ dg-error "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } } */
+/* a����a				{ dg-error "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } } */
+/* a������a				{ dg-error "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } } */
+/*					{ dg-error "invalid UTF-8 character <bf>" "" { target c++23 } .-1 } */
diff --git a/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-4.C b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-4.C
new file mode 100644
index 0000000..1dc65e3
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-4.C
@@ -0,0 +1,43 @@
+// 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 -pedantic-errors -Wno-invalid-utf8" }
+
+// a€߿ࠀ퟿𐀀􏿿a		{ dg-bogus "invalid UTF-8 character" }
+// a�a					{ dg-bogus "invalid UTF-8 character <80>" }
+// a�a					{ dg-bogus "invalid UTF-8 character <bf>" }
+// a�a					{ dg-bogus "invalid UTF-8 character <c0>" }
+// a�a					{ dg-bogus "invalid UTF-8 character <c1>" }
+// a�a					{ dg-bogus "invalid UTF-8 character <f5>" }
+// a�a					{ dg-bogus "invalid UTF-8 character <ff>" }
+// a�a					{ dg-bogus "invalid UTF-8 character <c2>" }
+// a�a					{ dg-bogus "invalid UTF-8 character <e0>" }
+// a���a				{ dg-bogus "invalid UTF-8 character <e0><80><bf>" }
+// a���a				{ dg-bogus "invalid UTF-8 character <e0><9f><80>" }
+// a�a					{ dg-bogus "invalid UTF-8 character <e0><bf>" }
+// a�a					{ dg-bogus "invalid UTF-8 character <ec><80>" }
+// a���a				{ dg-bogus "invalid UTF-8 character <ed><a0><80>" }
+// a����a				{ dg-bogus "invalid UTF-8 character <f0><80><80><80>" }
+// a����a				{ dg-bogus "invalid UTF-8 character <f0><8f><bf><bf>" }
+// a����a				{ dg-bogus "invalid UTF-8 character <f4><90><80><80>" }
+// a������a				{ dg-bogus "invalid UTF-8 character <fd><bf><bf><bf>" }
+//					{ dg-bogus "invalid UTF-8 character <bf>" "" { target *-*-* } .-1 }
+/* a€߿ࠀ퟿𐀀􏿿a		{ dg-bogus "invalid UTF-8 character" } */
+/* a�a					{ dg-bogus "invalid UTF-8 character <80>" } */
+/* a�a					{ dg-bogus "invalid UTF-8 character <bf>" } */
+/* a�a					{ dg-bogus "invalid UTF-8 character <c0>" } */
+/* a�a					{ dg-bogus "invalid UTF-8 character <c1>" } */
+/* a�a					{ dg-bogus "invalid UTF-8 character <f5>" } */
+/* a�a					{ dg-bogus "invalid UTF-8 character <ff>" } */
+/* a�a					{ dg-bogus "invalid UTF-8 character <c2>" } */
+/* a�a					{ dg-bogus "invalid UTF-8 character <e0>" } */
+/* a���a				{ dg-bogus "invalid UTF-8 character <e0><80><bf>" } */
+/* a���a				{ dg-bogus "invalid UTF-8 character <e0><9f><80>" } */
+/* a�a					{ dg-bogus "invalid UTF-8 character <e0><bf>" } */
+/* a�a					{ dg-bogus "invalid UTF-8 character <ec><80>" } */
+/* a���a				{ dg-bogus "invalid UTF-8 character <ed><a0><80>" } */
+/* a����a				{ dg-bogus "invalid UTF-8 character <f0><80><80><80>" } */
+/* a����a				{ dg-bogus "invalid UTF-8 character <f0><8f><bf><bf>" } */
+/* a����a				{ dg-bogus "invalid UTF-8 character <f4><90><80><80>" } */
+/* a������a				{ dg-bogus "invalid UTF-8 character <fd><bf><bf><bf>" } */
+/*					{ dg-bogus "invalid UTF-8 character <bf>" "" { target *-*-* } .-1 } */
diff --git a/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-5.C b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-5.C
new file mode 100644
index 0000000..f0140ba
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-5.C
@@ -0,0 +1,80 @@
+// 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 { target c++11 } }
+// { dg-options "-finput-charset=UTF-8" }
+
+char32_t a = U'�';				// { dg-warning "invalid UTF-8 character <80>" "" { target c++23 } }
+char32_t b = U'�';				// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } }
+char32_t c = U'�';				// { dg-warning "invalid UTF-8 character <c0>" "" { target c++23 } }
+char32_t d = U'�';				// { dg-warning "invalid UTF-8 character <c1>" "" { target c++23 } }
+char32_t e = U'�';				// { dg-warning "invalid UTF-8 character <f5>" "" { target c++23 } }
+char32_t f = U'�';				// { dg-warning "invalid UTF-8 character <ff>" "" { target c++23 } }
+char32_t g = U'�';				// { dg-warning "invalid UTF-8 character <c2>" "" { target c++23 } }
+char32_t h = U'�';				// { dg-warning "invalid UTF-8 character <e0>" "" { target c++23 } }
+char32_t i = U'���';				// { dg-warning "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+char32_t j = U'���';				// { dg-warning "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+char32_t k = U'�';				// { dg-warning "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+char32_t l = U'�';				// { dg-warning "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+char32_t m = U'���';				// { dg-warning "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+char32_t n = U'����';				// { dg-warning "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+char32_t o = U'����';				// { dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+char32_t p = U'����';				// { dg-warning "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+char32_t q = U'������';				// { dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
+auto A = U"€߿ࠀ퟿𐀀􏿿";		// { dg-bogus "invalid UTF-8 character" }
+auto B = U"�";					// { dg-warning "invalid UTF-8 character <80>" "" { target c++23 } }
+auto C = U"�";					// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } }
+auto D = U"�";					// { dg-warning "invalid UTF-8 character <c0>" "" { target c++23 } }
+auto E = U"�";					// { dg-warning "invalid UTF-8 character <c1>" "" { target c++23 } }
+auto F = U"�";					// { dg-warning "invalid UTF-8 character <f5>" "" { target c++23 } }
+auto G = U"�";					// { dg-warning "invalid UTF-8 character <ff>" "" { target c++23 } }
+auto H = U"�";					// { dg-warning "invalid UTF-8 character <c2>" "" { target c++23 } }
+auto I = U"�";					// { dg-warning "invalid UTF-8 character <e0>" "" { target c++23 } }
+auto J = U"���";				// { dg-warning "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+auto K = U"���";				// { dg-warning "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+auto L = U"�";					// { dg-warning "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+auto M = U"�";					// { dg-warning "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+auto N = U"���";				// { dg-warning "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+auto O = U"����";				// { dg-warning "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+auto P = U"����";				// { dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+auto Q = U"����";				// { dg-warning "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+auto R = U"������";				// { dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
+auto A1 = UR"(€߿ࠀ퟿𐀀􏿿)";		// { dg-bogus "invalid UTF-8 character" }
+auto B1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <80>" "" { target c++23 } }
+auto C1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } }
+auto D1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <c0>" "" { target c++23 } }
+auto E1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <c1>" "" { target c++23 } }
+auto F1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <f5>" "" { target c++23 } }
+auto G1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <ff>" "" { target c++23 } }
+auto H1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <c2>" "" { target c++23 } }
+auto I1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <e0>" "" { target c++23 } }
+auto J1 = UR"(���)";				// { dg-warning "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+auto K1 = UR"(���)";				// { dg-warning "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+auto L1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+auto M1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+auto N1 = UR"(���)";				// { dg-warning "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+auto O1 = UR"(����)";				// { dg-warning "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+auto P1 = UR"(����)";				// { dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+auto Q1 = UR"(����)";				// { dg-warning "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+auto R1 = UR"(������)";				// { dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
+auto A2 = u8"€߿ࠀ퟿𐀀􏿿";		// { dg-bogus "invalid UTF-8 character" }
+auto B2 = u8"�";				// { dg-warning "invalid UTF-8 character <80>" "" { target c++23 } }
+auto C2 = u8"�";				// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } }
+auto D2 = u8"�";				// { dg-warning "invalid UTF-8 character <c0>" "" { target c++23 } }
+auto E2 = u8"�";				// { dg-warning "invalid UTF-8 character <c1>" "" { target c++23 } }
+auto F2 = u8"�";				// { dg-warning "invalid UTF-8 character <f5>" "" { target c++23 } }
+auto G2 = u8"�";				// { dg-warning "invalid UTF-8 character <ff>" "" { target c++23 } }
+auto H2 = u8"�";				// { dg-warning "invalid UTF-8 character <c2>" "" { target c++23 } }
+auto I2 = u8"�";				// { dg-warning "invalid UTF-8 character <e0>" "" { target c++23 } }
+auto J2 = u8"���";				// { dg-warning "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+auto K2 = u8"���";				// { dg-warning "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+auto L2 = u8"�";				// { dg-warning "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+auto M2 = u8"�";				// { dg-warning "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+auto N2 = u8"���";				// { dg-warning "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+auto O2 = u8"����";				// { dg-warning "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+auto P2 = u8"����";				// { dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+auto Q2 = u8"����";				// { dg-warning "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+auto R2 = u8"������";				// { dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
diff --git a/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-6.C b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-6.C
new file mode 100644
index 0000000..01023d3
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-6.C
@@ -0,0 +1,80 @@
+// 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 { target c++11 } }
+// { dg-options "-finput-charset=UTF-8 -pedantic" }
+
+char32_t a = U'�';				// { dg-warning "invalid UTF-8 character <80>" "" { target c++23 } }
+char32_t b = U'�';				// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } }
+char32_t c = U'�';				// { dg-warning "invalid UTF-8 character <c0>" "" { target c++23 } }
+char32_t d = U'�';				// { dg-warning "invalid UTF-8 character <c1>" "" { target c++23 } }
+char32_t e = U'�';				// { dg-warning "invalid UTF-8 character <f5>" "" { target c++23 } }
+char32_t f = U'�';				// { dg-warning "invalid UTF-8 character <ff>" "" { target c++23 } }
+char32_t g = U'�';				// { dg-warning "invalid UTF-8 character <c2>" "" { target c++23 } }
+char32_t h = U'�';				// { dg-warning "invalid UTF-8 character <e0>" "" { target c++23 } }
+char32_t i = U'���';				// { dg-warning "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+char32_t j = U'���';				// { dg-warning "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+char32_t k = U'�';				// { dg-warning "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+char32_t l = U'�';				// { dg-warning "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+char32_t m = U'���';				// { dg-warning "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+char32_t n = U'����';				// { dg-warning "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+char32_t o = U'����';				// { dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+char32_t p = U'����';				// { dg-warning "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+char32_t q = U'������';				// { dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
+auto A = U"€߿ࠀ퟿𐀀􏿿";		// { dg-bogus "invalid UTF-8 character" }
+auto B = U"�";					// { dg-warning "invalid UTF-8 character <80>" "" { target c++23 } }
+auto C = U"�";					// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } }
+auto D = U"�";					// { dg-warning "invalid UTF-8 character <c0>" "" { target c++23 } }
+auto E = U"�";					// { dg-warning "invalid UTF-8 character <c1>" "" { target c++23 } }
+auto F = U"�";					// { dg-warning "invalid UTF-8 character <f5>" "" { target c++23 } }
+auto G = U"�";					// { dg-warning "invalid UTF-8 character <ff>" "" { target c++23 } }
+auto H = U"�";					// { dg-warning "invalid UTF-8 character <c2>" "" { target c++23 } }
+auto I = U"�";					// { dg-warning "invalid UTF-8 character <e0>" "" { target c++23 } }
+auto J = U"���";				// { dg-warning "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+auto K = U"���";				// { dg-warning "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+auto L = U"�";					// { dg-warning "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+auto M = U"�";					// { dg-warning "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+auto N = U"���";				// { dg-warning "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+auto O = U"����";				// { dg-warning "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+auto P = U"����";				// { dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+auto Q = U"����";				// { dg-warning "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+auto R = U"������";				// { dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
+auto A1 = UR"(€߿ࠀ퟿𐀀􏿿)";		// { dg-bogus "invalid UTF-8 character" }
+auto B1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <80>" "" { target c++23 } }
+auto C1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } }
+auto D1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <c0>" "" { target c++23 } }
+auto E1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <c1>" "" { target c++23 } }
+auto F1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <f5>" "" { target c++23 } }
+auto G1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <ff>" "" { target c++23 } }
+auto H1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <c2>" "" { target c++23 } }
+auto I1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <e0>" "" { target c++23 } }
+auto J1 = UR"(���)";				// { dg-warning "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+auto K1 = UR"(���)";				// { dg-warning "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+auto L1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+auto M1 = UR"(�)";				// { dg-warning "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+auto N1 = UR"(���)";				// { dg-warning "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+auto O1 = UR"(����)";				// { dg-warning "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+auto P1 = UR"(����)";				// { dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+auto Q1 = UR"(����)";				// { dg-warning "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+auto R1 = UR"(������)";				// { dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
+auto A2 = u8"€߿ࠀ퟿𐀀􏿿";		// { dg-bogus "invalid UTF-8 character" }
+auto B2 = u8"�";				// { dg-warning "invalid UTF-8 character <80>" "" { target c++23 } }
+auto C2 = u8"�";				// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } }
+auto D2 = u8"�";				// { dg-warning "invalid UTF-8 character <c0>" "" { target c++23 } }
+auto E2 = u8"�";				// { dg-warning "invalid UTF-8 character <c1>" "" { target c++23 } }
+auto F2 = u8"�";				// { dg-warning "invalid UTF-8 character <f5>" "" { target c++23 } }
+auto G2 = u8"�";				// { dg-warning "invalid UTF-8 character <ff>" "" { target c++23 } }
+auto H2 = u8"�";				// { dg-warning "invalid UTF-8 character <c2>" "" { target c++23 } }
+auto I2 = u8"�";				// { dg-warning "invalid UTF-8 character <e0>" "" { target c++23 } }
+auto J2 = u8"���";				// { dg-warning "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+auto K2 = u8"���";				// { dg-warning "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+auto L2 = u8"�";				// { dg-warning "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+auto M2 = u8"�";				// { dg-warning "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+auto N2 = u8"���";				// { dg-warning "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+auto O2 = u8"����";				// { dg-warning "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+auto P2 = u8"����";				// { dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+auto Q2 = u8"����";				// { dg-warning "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+auto R2 = u8"������";				// { dg-warning "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
diff --git a/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-7.C b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-7.C
new file mode 100644
index 0000000..7991a64
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-7.C
@@ -0,0 +1,80 @@
+// 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 { target c++11 } }
+// { dg-options "-finput-charset=UTF-8 -pedantic-errors" }
+
+char32_t a = U'�';				// { dg-error "invalid UTF-8 character <80>" "" { target c++23 } }
+char32_t b = U'�';				// { dg-error "invalid UTF-8 character <bf>" "" { target c++23 } }
+char32_t c = U'�';				// { dg-error "invalid UTF-8 character <c0>" "" { target c++23 } }
+char32_t d = U'�';				// { dg-error "invalid UTF-8 character <c1>" "" { target c++23 } }
+char32_t e = U'�';				// { dg-error "invalid UTF-8 character <f5>" "" { target c++23 } }
+char32_t f = U'�';				// { dg-error "invalid UTF-8 character <ff>" "" { target c++23 } }
+char32_t g = U'�';				// { dg-error "invalid UTF-8 character <c2>" "" { target c++23 } }
+char32_t h = U'�';				// { dg-error "invalid UTF-8 character <e0>" "" { target c++23 } }
+char32_t i = U'���';				// { dg-error "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+char32_t j = U'���';				// { dg-error "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+char32_t k = U'�';				// { dg-error "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+char32_t l = U'�';				// { dg-error "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+char32_t m = U'���';				// { dg-error "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+char32_t n = U'����';				// { dg-error "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+char32_t o = U'����';				// { dg-error "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+char32_t p = U'����';				// { dg-error "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+char32_t q = U'������';				// { dg-error "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-error "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
+auto A = U"€߿ࠀ퟿𐀀􏿿";		// { dg-bogus "invalid UTF-8 character" }
+auto B = U"�";					// { dg-error "invalid UTF-8 character <80>" "" { target c++23 } }
+auto C = U"�";					// { dg-error "invalid UTF-8 character <bf>" "" { target c++23 } }
+auto D = U"�";					// { dg-error "invalid UTF-8 character <c0>" "" { target c++23 } }
+auto E = U"�";					// { dg-error "invalid UTF-8 character <c1>" "" { target c++23 } }
+auto F = U"�";					// { dg-error "invalid UTF-8 character <f5>" "" { target c++23 } }
+auto G = U"�";					// { dg-error "invalid UTF-8 character <ff>" "" { target c++23 } }
+auto H = U"�";					// { dg-error "invalid UTF-8 character <c2>" "" { target c++23 } }
+auto I = U"�";					// { dg-error "invalid UTF-8 character <e0>" "" { target c++23 } }
+auto J = U"���";				// { dg-error "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+auto K = U"���";				// { dg-error "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+auto L = U"�";					// { dg-error "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+auto M = U"�";					// { dg-error "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+auto N = U"���";				// { dg-error "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+auto O = U"����";				// { dg-error "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+auto P = U"����";				// { dg-error "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+auto Q = U"����";				// { dg-error "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+auto R = U"������";				// { dg-error "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-error "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
+auto A1 = UR"(€߿ࠀ퟿𐀀􏿿)";		// { dg-bogus "invalid UTF-8 character" }
+auto B1 = UR"(�)";				// { dg-error "invalid UTF-8 character <80>" "" { target c++23 } }
+auto C1 = UR"(�)";				// { dg-error "invalid UTF-8 character <bf>" "" { target c++23 } }
+auto D1 = UR"(�)";				// { dg-error "invalid UTF-8 character <c0>" "" { target c++23 } }
+auto E1 = UR"(�)";				// { dg-error "invalid UTF-8 character <c1>" "" { target c++23 } }
+auto F1 = UR"(�)";				// { dg-error "invalid UTF-8 character <f5>" "" { target c++23 } }
+auto G1 = UR"(�)";				// { dg-error "invalid UTF-8 character <ff>" "" { target c++23 } }
+auto H1 = UR"(�)";				// { dg-error "invalid UTF-8 character <c2>" "" { target c++23 } }
+auto I1 = UR"(�)";				// { dg-error "invalid UTF-8 character <e0>" "" { target c++23 } }
+auto J1 = UR"(���)";				// { dg-error "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+auto K1 = UR"(���)";				// { dg-error "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+auto L1 = UR"(�)";				// { dg-error "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+auto M1 = UR"(�)";				// { dg-error "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+auto N1 = UR"(���)";				// { dg-error "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+auto O1 = UR"(����)";				// { dg-error "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+auto P1 = UR"(����)";				// { dg-error "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+auto Q1 = UR"(����)";				// { dg-error "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+auto R1 = UR"(������)";				// { dg-error "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-error "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
+auto A2 = u8"€߿ࠀ퟿𐀀􏿿";		// { dg-bogus "invalid UTF-8 character" }
+auto B2 = u8"�";				// { dg-error "invalid UTF-8 character <80>" "" { target c++23 } }
+auto C2 = u8"�";				// { dg-error "invalid UTF-8 character <bf>" "" { target c++23 } }
+auto D2 = u8"�";				// { dg-error "invalid UTF-8 character <c0>" "" { target c++23 } }
+auto E2 = u8"�";				// { dg-error "invalid UTF-8 character <c1>" "" { target c++23 } }
+auto F2 = u8"�";				// { dg-error "invalid UTF-8 character <f5>" "" { target c++23 } }
+auto G2 = u8"�";				// { dg-error "invalid UTF-8 character <ff>" "" { target c++23 } }
+auto H2 = u8"�";				// { dg-error "invalid UTF-8 character <c2>" "" { target c++23 } }
+auto I2 = u8"�";				// { dg-error "invalid UTF-8 character <e0>" "" { target c++23 } }
+auto J2 = u8"���";				// { dg-error "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+auto K2 = u8"���";				// { dg-error "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+auto L2 = u8"�";				// { dg-error "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+auto M2 = u8"�";				// { dg-error "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+auto N2 = u8"���";				// { dg-error "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+auto O2 = u8"����";				// { dg-error "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+auto P2 = u8"����";				// { dg-error "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+auto Q2 = u8"����";				// { dg-error "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+auto R2 = u8"������";				// { dg-error "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-error "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
diff --git a/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-8.C b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-8.C
new file mode 100644
index 0000000..95c8a91
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-8.C
@@ -0,0 +1,80 @@
+// 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 { target c++11 } }
+// { dg-options "-finput-charset=UTF-8 -pedantic-errors -Wno-invalid-utf8" }
+
+char32_t a = U'�';				// { dg-bogus "invalid UTF-8 character <80>" "" { target c++23 } }
+char32_t b = U'�';				// { dg-bogus "invalid UTF-8 character <bf>" "" { target c++23 } }
+char32_t c = U'�';				// { dg-bogus "invalid UTF-8 character <c0>" "" { target c++23 } }
+char32_t d = U'�';				// { dg-bogus "invalid UTF-8 character <c1>" "" { target c++23 } }
+char32_t e = U'�';				// { dg-bogus "invalid UTF-8 character <f5>" "" { target c++23 } }
+char32_t f = U'�';				// { dg-bogus "invalid UTF-8 character <ff>" "" { target c++23 } }
+char32_t g = U'�';				// { dg-bogus "invalid UTF-8 character <c2>" "" { target c++23 } }
+char32_t h = U'�';				// { dg-bogus "invalid UTF-8 character <e0>" "" { target c++23 } }
+char32_t i = U'���';				// { dg-bogus "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+char32_t j = U'���';				// { dg-bogus "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+char32_t k = U'�';				// { dg-bogus "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+char32_t l = U'�';				// { dg-bogus "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+char32_t m = U'���';				// { dg-bogus "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+char32_t n = U'����';				// { dg-bogus "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+char32_t o = U'����';				// { dg-bogus "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+char32_t p = U'����';				// { dg-bogus "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+char32_t q = U'������';				// { dg-bogus "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-bogus "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
+auto A = U"€߿ࠀ퟿𐀀􏿿";		// { dg-bogus "invalid UTF-8 character" }
+auto B = U"�";					// { dg-bogus "invalid UTF-8 character <80>" "" { target c++23 } }
+auto C = U"�";					// { dg-bogus "invalid UTF-8 character <bf>" "" { target c++23 } }
+auto D = U"�";					// { dg-bogus "invalid UTF-8 character <c0>" "" { target c++23 } }
+auto E = U"�";					// { dg-bogus "invalid UTF-8 character <c1>" "" { target c++23 } }
+auto F = U"�";					// { dg-bogus "invalid UTF-8 character <f5>" "" { target c++23 } }
+auto G = U"�";					// { dg-bogus "invalid UTF-8 character <ff>" "" { target c++23 } }
+auto H = U"�";					// { dg-bogus "invalid UTF-8 character <c2>" "" { target c++23 } }
+auto I = U"�";					// { dg-bogus "invalid UTF-8 character <e0>" "" { target c++23 } }
+auto J = U"���";				// { dg-bogus "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+auto K = U"���";				// { dg-bogus "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+auto L = U"�";					// { dg-bogus "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+auto M = U"�";					// { dg-bogus "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+auto N = U"���";				// { dg-bogus "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+auto O = U"����";				// { dg-bogus "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+auto P = U"����";				// { dg-bogus "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+auto Q = U"����";				// { dg-bogus "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+auto R = U"������";				// { dg-bogus "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-bogus "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
+auto A1 = UR"(€߿ࠀ퟿𐀀􏿿)";		// { dg-bogus "invalid UTF-8 character" }
+auto B1 = UR"(�)";				// { dg-bogus "invalid UTF-8 character <80>" "" { target c++23 } }
+auto C1 = UR"(�)";				// { dg-bogus "invalid UTF-8 character <bf>" "" { target c++23 } }
+auto D1 = UR"(�)";				// { dg-bogus "invalid UTF-8 character <c0>" "" { target c++23 } }
+auto E1 = UR"(�)";				// { dg-bogus "invalid UTF-8 character <c1>" "" { target c++23 } }
+auto F1 = UR"(�)";				// { dg-bogus "invalid UTF-8 character <f5>" "" { target c++23 } }
+auto G1 = UR"(�)";				// { dg-bogus "invalid UTF-8 character <ff>" "" { target c++23 } }
+auto H1 = UR"(�)";				// { dg-bogus "invalid UTF-8 character <c2>" "" { target c++23 } }
+auto I1 = UR"(�)";				// { dg-bogus "invalid UTF-8 character <e0>" "" { target c++23 } }
+auto J1 = UR"(���)";				// { dg-bogus "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+auto K1 = UR"(���)";				// { dg-bogus "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+auto L1 = UR"(�)";				// { dg-bogus "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+auto M1 = UR"(�)";				// { dg-bogus "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+auto N1 = UR"(���)";				// { dg-bogus "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+auto O1 = UR"(����)";				// { dg-bogus "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+auto P1 = UR"(����)";				// { dg-bogus "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+auto Q1 = UR"(����)";				// { dg-bogus "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+auto R1 = UR"(������)";				// { dg-bogus "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-bogus "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
+auto A2 = u8"€߿ࠀ퟿𐀀􏿿";		// { dg-bogus "invalid UTF-8 character" }
+auto B2 = u8"�";				// { dg-bogus "invalid UTF-8 character <80>" "" { target c++23 } }
+auto C2 = u8"�";				// { dg-bogus "invalid UTF-8 character <bf>" "" { target c++23 } }
+auto D2 = u8"�";				// { dg-bogus "invalid UTF-8 character <c0>" "" { target c++23 } }
+auto E2 = u8"�";				// { dg-bogus "invalid UTF-8 character <c1>" "" { target c++23 } }
+auto F2 = u8"�";				// { dg-bogus "invalid UTF-8 character <f5>" "" { target c++23 } }
+auto G2 = u8"�";				// { dg-bogus "invalid UTF-8 character <ff>" "" { target c++23 } }
+auto H2 = u8"�";				// { dg-bogus "invalid UTF-8 character <c2>" "" { target c++23 } }
+auto I2 = u8"�";				// { dg-bogus "invalid UTF-8 character <e0>" "" { target c++23 } }
+auto J2 = u8"���";				// { dg-bogus "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+auto K2 = u8"���";				// { dg-bogus "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+auto L2 = u8"�";				// { dg-bogus "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+auto M2 = u8"�";				// { dg-bogus "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+auto N2 = u8"���";				// { dg-bogus "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+auto O2 = u8"����";				// { dg-bogus "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+auto P2 = u8"����";				// { dg-bogus "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+auto Q2 = u8"����";				// { dg-bogus "invalid UTF-8 character <f4><90><80><80>" "" { target c++23 } }
+auto R2 = u8"������";				// { dg-bogus "invalid UTF-8 character <fd><bf><bf><bf>" "" { target c++23 } }
+						// { dg-bogus "invalid UTF-8 character <bf>" "" { target c++23 } .-1 }
diff --git a/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-9.C b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-9.C
new file mode 100644
index 0000000..0afc945
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/Winvalid-utf8-9.C
@@ -0,0 +1,25 @@
+// 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" }
+
+#define I(x)
+I(€߿ࠀ퟿𐀀􏿿)	// { dg-bogus "invalid UTF-8 character" }
+                                // { dg-error "is not valid in an identifier" "" { target *-*-* } .-1 }
+I(�)				// { dg-warning "invalid UTF-8 character <80>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <bf>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <c0>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <c1>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <f5>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <ff>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <c2>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <e0>" "" { target c++23 } }
+I(���)				// { dg-warning "invalid UTF-8 character <e0><80><bf>" "" { target c++23 } }
+I(���)				// { dg-warning "invalid UTF-8 character <e0><9f><80>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <e0><bf>" "" { target c++23 } }
+I(�)				// { dg-warning "invalid UTF-8 character <ec><80>" "" { target c++23 } }
+I(���)				// { dg-warning "invalid UTF-8 character <ed><a0><80>" "" { target c++23 } }
+I(����)				// { dg-warning "invalid UTF-8 character <f0><80><80><80>" "" { target c++23 } }
+I(����)				// { dg-warning "invalid UTF-8 character <f0><8f><bf><bf>" "" { target c++23 } }
+I(����)				// { dg-error "is not valid in an identifier" }
+I(������)			// { dg-error "is not valid in an identifier" }