Re: [PATCH] preprocessor: Implement C++23 P2437R1 - Support for #warning [PR106646]

[Jason Merrill via Gcc-patches]

On 8/22/22 02:53, Jakub Jelinek wrote:

Hi!

On Thu, Aug 18, 2022 at 11:02:44PM +0000, Joseph Myers wrote:

ISO C2x standardizes the existing #warning extension.  Arrange
accordingly for it not to be diagnosed with -std=c2x -pedantic, but to
be diagnosed with -Wc11-c2x-compat.

And here is the corresponding C++ version.
Don't pedwarn about this for C++23/GNU++23 and tweak the diagnostics
for C++ otherwise, + testsuite coverage.
The diagnostic wording is similar e.g. to the #elifdef diagnostics.

So far lightly tested, ok for trunk if it passes full bootstrap/regtest?

OK.

2022-08-22  Jakub Jelinek  <ja...@redhat.com>

        PR c++/106646
        * init.cc: Implement C++23 P2437R1 - Support for #warning.
        (lang_defaults): Set warning_directive for GNUCXX23 and CXX23.
        * directives.cc (directive_diagnostics): Use different wording of
        #warning pedwarn for C++.

        * g++.dg/cpp/warning-1.C: New test.
        * g++.dg/cpp/warning-2.C: New test.
        * g++.dg/cpp/warning-3.C: New test.

--- libcpp/init.cc.jj   2022-08-20 10:25:17.613071845 +0200
+++ libcpp/init.cc      2022-08-22 11:30:57.642622570 +0200
@@ -123,8 +123,8 @@ static const struct lang_flags lang_defa
    /* CXX17    */  { 1,  1,  1,  1,  1,  1,  1,   1,   1,   1,    1,     1,    
 0,   1,      0,   1,     0,   0,   0,      0,      0 },
    /* GNUCXX20 */  { 1,  1,  1,  1,  1,  0,  1,   1,   1,   1,    1,     1,    
 0,   1,      1,   1,     0,   0,   0,      0,      0 },
    /* CXX20    */  { 1,  1,  1,  1,  1,  1,  1,   1,   1,   1,    1,     1,    
 0,   1,      1,   1,     0,   0,   0,      0,      0 },
-  /* GNUCXX23 */  { 1,  1,  1,  1,  1,  0,  1,   1,   1,   1,    1,     1,     
0,   1,      1,   1,     0,   1,   1,      0,      1 },
-  /* CXX23    */  { 1,  1,  1,  1,  1,  1,  1,   1,   1,   1,    1,     1,     
0,   1,      1,   1,     0,   1,   1,      0,      1 },
+  /* GNUCXX23 */  { 1,  1,  1,  1,  1,  0,  1,   1,   1,   1,    1,     1,     
0,   1,      1,   1,     0,   1,   1,      1,      1 },
+  /* CXX23    */  { 1,  1,  1,  1,  1,  1,  1,   1,   1,   1,    1,     1,     
0,   1,      1,   1,     0,   1,   1,      1,      1 },
    /* ASM      */  { 0,  0,  1,  0,  0,  0,  0,   0,   0,   0,    0,     0,    
 0,   0,      0,   0,     0,   0,   0,      0,      0 }
  };

--- libcpp/directives.cc.jj 2022-08-19 16:00:05.295386974 +0200

+++ libcpp/directives.cc        2022-08-22 11:30:03.239357642 +0200
@@ -388,8 +388,14 @@ directive_diagnostics (cpp_reader *pfile
        else if (dir == &dtable[T_WARNING])
        {
          if (CPP_PEDANTIC (pfile) && !CPP_OPTION (pfile, warning_directive))
-           cpp_error (pfile, CPP_DL_PEDWARN,
-                      "#%s before C2X is a GCC extension", dir->name);
+           {
+             if (CPP_OPTION (pfile, cplusplus))
+               cpp_error (pfile, CPP_DL_PEDWARN,
+                          "#%s before C++23 is a GCC extension", dir->name);
+             else
+               cpp_error (pfile, CPP_DL_PEDWARN,
+                          "#%s before C2X is a GCC extension", dir->name);
+           }
          else if (CPP_OPTION (pfile, cpp_warn_c11_c2x_compat) > 0)
            cpp_warning (pfile, CPP_W_C11_C2X_COMPAT,
                         "#%s before C2X is a GCC extension", dir->name);
--- gcc/testsuite/g++.dg/cpp/warning-1.C.jj     2022-08-22 11:39:41.284547323 
+0200
+++ gcc/testsuite/g++.dg/cpp/warning-1.C        2022-08-22 11:44:03.925988332 
+0200
@@ -0,0 +1,6 @@
+// P2437R1 - Support for #warning
+// { dg-do preprocess }
+// { dg-options "-pedantic-errors" }
+
+#warning example text /* { dg-warning "example text" } */
+// { dg-error "#warning before C\\\+\\\+23 is a GCC extension" "pedantic" { 
target c++20_down } .-1 }
--- gcc/testsuite/g++.dg/cpp/warning-2.C.jj     2022-08-22 11:39:44.116509055 
+0200
+++ gcc/testsuite/g++.dg/cpp/warning-2.C        2022-08-22 11:44:14.933839041 
+0200
@@ -0,0 +1,6 @@
+// P2437R1 - Support for #warning
+// { dg-do preprocess }
+// { dg-options "-pedantic" }
+
+#warning example text /* { dg-warning "example text" } */
+// { dg-warning "#warning before C\\\+\\\+23 is a GCC extension" "pedantic" { 
target c++20_down } .-1 }
--- gcc/testsuite/g++.dg/cpp/warning-3.C.jj     2022-08-22 11:39:47.020469826 
+0200
+++ gcc/testsuite/g++.dg/cpp/warning-3.C        2022-08-22 11:42:23.640348405 
+0200
@@ -0,0 +1,6 @@
+// P2437R1 - Support for #warning
+// { dg-do preprocess }
+// { dg-options "" }
+
+#warning example text /* { dg-warning "example text" } */
+// { dg-bogus "#warning before C\\\+\\\+23 is a GCC extension" "" { target 
*-*-* } .-1 }


        Jakub