The C preprocessor is intended only for macro processing of C, C++ and
Objective C source files. For macro processing of other files, you are
strongly encouraged to use alternatives like M4, which will likely give
-you better results and avoid many problems. For example, the C
-preprocessor sometimes outputs extra white space to avoid inadvertent C
-token concatenation, and this may cause problems with other languages.
+you better results and avoid many problems. For example, normally the C
+preprocessor does not preserve arbitrary whitespace verbatim, but
+instead replaces each sequence with a single space.
For use on C-like source files, the C preprocessor provides four
separate facilities that you can use as you see fit:
@item -C
@findex -C
-Do not discard comments: pass them through to the output file.
-Comments appearing in arguments of a macro call will be copied to the
-output before the expansion of the macro call.
-
-You should be prepared for unwanted side effects when using -C. For
+Do not discard comments. All comments are passed through to the output
+file, except for comments in processed directives, which are deleted
+along with the directive. Comments appearing in the expansion list of a
+macro will be preserved, and appear in place wherever the macro is
+invoked.
+
+You should be prepared for side effects when using -C; it causes the
+preprocessor to treat comments as tokens in their own right. For
example, macro redefinitions that were trivial when comments were
replaced by a single space might become significant when comments are
retained. Also, comments appearing at the start of what would be a
+2000-07-11 Neil Booth <NeilB@earthling.net>
+
+ * gcc.dg/cpp/cmdlne-C.c: New.
+
2000-07-09 Neil Booth <NeilB@earthling.net>
- * testsuite/gcc.dg/cpp/directiv.c: New tests.
- * testsuite/gcc.dg/cpp/undef1.c: Update.
+ * gcc.dg/cpp/directiv.c: New tests.
+ * gcc.dg/cpp/undef1.c: Update.
2000-07-08 Angela Marie Thomas <angela@cygnus.com>
--- /dev/null
+/* Copyright (C) 2000 Free Software Foundation, Inc. */
+
+/* { dg-do preprocess } */
+/* { dg-options -C } */
+
+/* Test -C doesn't fail with #define. #define is the tricky case,
+ being the only directive that remembers its comments.
+
+ -C treats comments as tokens in their own right, so e.g. comment at
+ the beginning of a directive turns it into a non-directive. */
+
+#define simple no comments
+#/**/define bad_directive /* { dg-error "invalid" } */
+#define/**/obj_like/**/(some)/**/thing/**/
+#define fun_like(/**/x/**/,/**/y/**/)/**/
+/**/#define not_a_macro
+
+#if !defined simple || !defined obj_like || !defined fun_like
+#error Missed some macros with -C
+#endif
+
+#ifdef not_a_macro
+#error not_a_macro is!
+#endif
+
+/* Check obj_like2 doesn't expect arguments, and fun_like does. */
+obj_like2
+fun_like (foo, bar)
+
+/* Check OK to redefine fun_like without comments in the params. */
+#define fun_like(x, y)/**/