tccpp.c: parse flag to accept stray \

This adds a PARSE_FLAG_ACCEPT_STRAYS parse flag to accept stray
backslashes in the source code, and uses it for pure preprocessing.

For absolutely correct behaviour of # stringification, we need to use
this flag when parsing macro definitions and in macro arguments, as
well; this patch does not yet do so. The test case for that is something
like

    #define STRINGIFY2(x) #x
    #define STRINGIFY(x) STRINGIFY2(x)

    STRINGIFY(\n)

which should produce "\n", not a parse error or "\\n".

See http://lists.nongnu.org/archive/html/tinycc-devel/2015-05/msg00002.html

2 files changed, 9 insertions, 2 deletions

diff --git a/tcc.h b/tcc.h
index 384e8de..a0d0635 100644
--- a/tcc.h
+++ b/tcc.h
@@ -1152,6 +1152,7 @@ ST_DATA TokenSym **table_ident;
                                         returned at eof */
 #define PARSE_FLAG_ASM_FILE 0x0008 /* we processing an asm file: '#' can be used for line comment, etc. */
 #define PARSE_FLAG_SPACES     0x0010 /* next() returns space tokens (for -E) */
+#define PARSE_FLAG_ACCEPT_STRAYS 0x0020 /* next() returns '\\' token */
 
 ST_FUNC TokenSym *tok_alloc(const char *str, int len);
 ST_FUNC char *get_tok_str(int v, CValue *cv);
diff --git a/tccpp.c b/tccpp.c
index 56779e0..ed3168f 100644
--- a/tccpp.c
+++ b/tccpp.c
@@ -2271,7 +2271,13 @@ static inline void next_nomacro1(void)
         } else {
             file->buf_ptr = p;
             ch = *p;
-            handle_stray();
+            if (parse_flags & PARSE_FLAG_ACCEPT_STRAYS) {
+                if (handle_stray_noerror() != 0) {
+                    goto parse_simple;
+                }
+            } else {
+                handle_stray();
+            }
             p = file->buf_ptr;
             goto redo_no_start;
         }
@@ -3307,7 +3313,7 @@ ST_FUNC int tcc_preprocess(TCCState *s1)
     ch = file->buf_ptr[0];
     tok_flags = TOK_FLAG_BOL | TOK_FLAG_BOF;
     parse_flags &= PARSE_FLAG_ASM_FILE;
-    parse_flags |= PARSE_FLAG_PREPROCESS | PARSE_FLAG_LINEFEED | PARSE_FLAG_SPACES;
+    parse_flags |= PARSE_FLAG_PREPROCESS | PARSE_FLAG_LINEFEED | PARSE_FLAG_SPACES | PARSE_FLAG_ACCEPT_STRAYS;
     token_seen = 0;
     file->line_ref = 0;
     file_ref = NULL;