c-pragma.c (handle_pragma_message): New function.

	* c-pragma.c (handle_pragma_message): New function.
	(init_pragma): Register handle_pragma_message.
	* doc/extend.texi (Diagnostic Pragmas): Added #pragma message
	documentation.

	* gcc.dg/pragma-message.c: New.

From-SVN: r138206

gcc/ChangeLog

+2008-07-28  Simon Baldwin  <simonb@google.com>
+
+	* c-pragma.c (handle_pragma_message): New function.
+	(init_pragma): Register handle_pragma_message.
+	* doc/extend.texi (Diagnostic Pragmas): Added #pragma message
+	documentation.
+
 2008-07-27  Victor Kaplansky  <victork@il.ibm.com>
 
 	PR tree-optimization/35252

gcc/c-pragma.c

@@ -1173,6 +1173,39 @@ handle_pragma_optimize(cpp_reader *ARG_UNUSED(dummy))
     }
 }
 
+/* Print a plain user-specified message.  */
+
+static void
+handle_pragma_message (cpp_reader *ARG_UNUSED(dummy))
+{
+  enum cpp_ttype token;
+  tree x, message = 0;
+
+  token = pragma_lex (&x);
+  if (token == CPP_OPEN_PAREN)
+    {
+      token = pragma_lex (&x);
+      if (token == CPP_STRING)
+        message = x;
+      else
+        GCC_BAD ("expected a string after %<#pragma message%>");
+      if (pragma_lex (&x) != CPP_CLOSE_PAREN)
+        GCC_BAD ("malformed %<#pragma message%>, ignored");
+    }
+  else if (token == CPP_STRING)
+    message = x;
+  else
+    GCC_BAD ("expected a string after %<#pragma message%>");
+
+  gcc_assert (message);
+
+  if (pragma_lex (&x) != CPP_EOF)
+    warning (OPT_Wpragmas, "junk at end of %<#pragma message%>");
+
+  if (TREE_STRING_LENGTH (message) > 1)
+    inform ("#pragma message: %s", TREE_STRING_POINTER (message));
+}
+
 /* A vector of registered pragma callbacks.  */
 
 DEF_VEC_O (pragma_handler);
@@ -1341,6 +1374,8 @@ init_pragma (void)
   c_register_pragma_with_expansion (0, "redefine_extname", handle_pragma_redefine_extname);
   c_register_pragma (0, "extern_prefix", handle_pragma_extern_prefix);
 
+  c_register_pragma_with_expansion (0, "message", handle_pragma_message);
+
 #ifdef REGISTER_TARGET_PRAGMAS
   REGISTER_TARGET_PRAGMAS ();
 #endif

gcc/doc/extend.texi

@@ -11616,6 +11616,35 @@ strict control over project policies.
 
 @end table
 
+GCC also offers a simple mechanism for printing messages during
+compilation.
+
+@table @code
+@item #pragma message @var{string}
+@cindex pragma, diagnostic
+
+Prints @var{string} as a compiler message on compilation.  The message
+is informational only, and is neither a compilation warning nor an error.
+
+@smallexample
+#pragma message "Compiling " __FILE__ "..."
+@end smallexample
+
+@var{string} may be parenthesized, and is printed with location
+information.  For example,
+
+@smallexample
+#define DO_PRAGMA(x) _Pragma (#x)
+#define TODO(x) DO_PRAGMA(message ("TODO - " #x))
+
+TODO(Remember to fix this)
+@end smallexample
+
+prints @samp{/tmp/file.c:4: note: #pragma message:
+TODO - Remember to fix this}.
+
+@end table
+
 @node Visibility Pragmas
 @subsection Visibility Pragmas
 

gcc/testsuite/ChangeLog

+2008-07-28  Simon Baldwin  <simonb@google.com>
+
+	* gcc.dg/pragma-message.c: New.
+
 2008-07-27  Victor Kaplansky  <victork@il.ibm.com>
 
 	PR tree-optimization/35252

gcc/testsuite/gcc.dg/pragma-message.c

+/* Test that #pragma message "..." writes compiler messages. */
+
+#pragma message                  /* { dg-warning "expected a string" } */
+#pragma message 0                /* { dg-warning "expected a string" } */
+#pragma message id               /* { dg-warning "expected a string" } */
+#pragma message (                /* { dg-warning "expected a string" } */
+#pragma message (0               /* { dg-warning "expected a string" } */
+#pragma message (id              /* { dg-warning "expected a string" } */
+#pragma message ()               /* { dg-warning "expected a string" } */
+#pragma message (0)              /* { dg-warning "expected a string" } */
+#pragma message (id)             /* { dg-warning "expected a string" } */
+
+/* gcc prefixes '#pragma message ...' output with filename and line number,
+   then 'note: #pragma message: ', allowing dg-message to check output.
+   If unexpected pragma messages are printed (anything not caught by a
+   matching dg-message), dejagnu will report these as excess errors.  */
+
+#pragma message "
+/* { dg-error "missing terminating" "" { target *-*-* } 18 } */
+/* { dg-warning "expected a string" "" { target *-*-* } 18 } */
+#pragma message "Bad 1
+/* { dg-error "missing terminating" "" { target *-*-* } 21 } */
+/* { dg-warning "expected a string" "" { target *-*-* } 21 } */
+#pragma message ("Bad 2
+/* { dg-error "missing terminating" "" { target *-*-* } 24 } */
+/* { dg-warning "expected a string" "" { target *-*-* } 24 } */
+#pragma message ("Bad 3"
+/* { dg-warning "malformed '#pragma message" "" { target *-*-* } 27 } */
+
+#pragma message "" junk
+/* { dg-warning "junk at end of '#pragma message'" "" { target *-*-* } 30 } */
+
+#pragma message ("") junk
+/* { dg-warning "junk at end of '#pragma message'" "" { target *-*-* } 33 } */
+
+#pragma message ""               /* No output expected for empty messages.  */
+#pragma message ("")
+
+#pragma message "Okay 1"         /* { dg-message "Okay 1" } */
+#pragma message ("Okay 2")       /* { dg-message "Okay 2" } */
+#define THREE "3"
+#pragma message ("Okay " THREE)  /* { dg-message "Okay 3" } */
+
+/* Create a TODO() that prints a message on compilation.  */
+#define DO_PRAGMA(x) _Pragma (#x)
+#define TODO(x) DO_PRAGMA(message ("TODO - " #x))
+TODO(Okay 4)                     /* { dg-message "TODO - Okay 4" } */
+
+#if 0
+#pragma message ("Not printed")
+#endif
+
+int unused;  /* Silence `ISO C forbids an empty translation unit' warning.  */