prepend diagnostics with source's path and include chain

When a diagnostic is issued for a problem in an included file,
the message show the include's path but it's often needed to
(quickly) know the chain of include files involved.

So, if the path associated with the diagnostic is different
than the path oft he source file and different from the path
of the previous message, prepend the message with a note
showing the source file's path. And, if any intermediate
include file is concerned, display the include chain
(possibly truncated or not displayed at all if too long).

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>

6 files changed, 103 insertions, 17 deletions

diff --git a/lib.c b/lib.c
index 4e8d7b45..dcbbb5b3 100644
--- a/lib.c
+++ b/lib.c
@@ -49,22 +49,98 @@
 #include "version.h"
 #include "bits.h"
 
+static int prettify(const char **fnamep)
+{
+	const char *name = *fnamep;
+	int len = strlen(name);
+
+	if (len > 2 && !memcmp(name, "./", 2)) {
+		name += 2;
+		len -= 2;
+	}
+
+	*fnamep = name;
+	return len;
+}
+
+static const char *show_include_chain(int stream, const char *base)
+{
+	static char buffer[200];
+	int len = 0;
+
+	while ((stream = stream_prev(stream)) >= 0) {
+		const char *p = stream_name(stream);
+		int pretty_len;
+
+		if (p == base)
+			break;
+
+		pretty_len = prettify(&p);
+		if (pretty_len <= 0)
+			break;
+
+		/*
+		 * At worst, we'll need " (through %s, ...)" in addition to the
+		 * new filename
+		 */
+		if (pretty_len + len + 20 > sizeof(buffer)) {
+			if (!len)
+				return "";
+			memcpy(buffer+len, ", ...", 5);
+			len += 5;
+			break;
+		}
+
+		if (!len) {
+			memcpy(buffer, " (through ", 10);
+			len = 10;
+		} else {
+			buffer[len++] = ',';
+			buffer[len++] = ' ';
+		}
+
+		memcpy(buffer+len, p, pretty_len);
+		len += pretty_len;
+	}
+	if (!len)
+		return "";
+
+	buffer[len] = ')';
+	buffer[len+1] = 0;
+	return buffer;
+}
+
+static const char *show_stream_name(struct position pos)
+{
+	const char *name = stream_name(pos.stream);
+	static const char *last;
+
+	if (name == base_filename)
+		return name;
+	if (name == last)
+		return name;
+	last = name;
+
+	fprintf(stderr, "%s: note: in included file%s:\n",
+		base_filename,
+		show_include_chain(pos.stream, base_filename));
+	return name;
+}
 
 static void do_warn(const char *type, struct position pos, const char * fmt, va_list args)
 {
 	static char buffer[512];
-	const char *name;
 
 	/* Shut up warnings if position is bad_token.pos */
 	if (pos.type == TOKEN_BAD)
 		return;
 
 	vsprintf(buffer, fmt, args);	
-	name = stream_name(pos.stream);
-		
+
 	fflush(stdout);
 	fprintf(stderr, "%s:%d:%d: %s%s%s\n",
-		name, pos.line, pos.pos, diag_prefix, type, buffer);
+		show_stream_name(pos), pos.line, pos.pos,
+		diag_prefix, type, buffer);
 }
 
 static int show_info = 1;
@@ -275,7 +351,7 @@ static struct symbol_list *sparse_file(const char *filename)
 	base_filename = filename;
 
 	// Tokenize the input stream
-	token = tokenize(filename, fd, NULL, includepath);
+	token = tokenize(filename, fd, -1, NULL, includepath);
 	close(fd);
 
 	return sparse_tokenstream(token);
diff --git a/pre-process.c b/pre-process.c
index 403e3507..6f4bf897 100644
--- a/pre-process.c
+++ b/pre-process.c
@@ -894,7 +894,7 @@ static void set_stream_include_path(struct stream *stream)
 #define PATH_MAX 4096	// for Hurd where it's not defined
 #endif
 
-static int try_include(const char *path, const char *filename, int flen, struct token **where, const char **next_path)
+static int try_include(struct position pos, const char *path, const char *filename, int flen, struct token **where, const char **next_path)
 {
 	int fd;
 	int plen = strlen(path);
@@ -911,7 +911,7 @@ static int try_include(const char *path, const char *filename, int flen, struct
 	fd = open(fullname, O_RDONLY);
 	if (fd >= 0) {
 		char *streamname = xmemdup(fullname, plen + flen);
-		*where = tokenize(streamname, fd, *where, next_path);
+		*where = tokenize(streamname, fd, pos.stream, *where, next_path);
 		close(fd);
 		return 1;
 	}
@@ -923,7 +923,7 @@ static int do_include_path(const char **pptr, struct token **list, struct token
 	const char *path;
 
 	while ((path = *pptr++) != NULL) {
-		if (!try_include(path, filename, flen, list, pptr))
+		if (!try_include(token->pos, path, filename, flen, list, pptr))
 			continue;
 		return 1;
 	}
@@ -966,7 +966,7 @@ static int handle_include_path(struct stream *stream, struct token **list, struc
 
 	/* Absolute path? */
 	if (filename[0] == '/') {
-		if (try_include("", filename, flen, list, includepath))
+		if (try_include(token->pos, "", filename, flen, list, includepath))
 			return 0;
 		goto out;
 	}
@@ -2091,7 +2091,7 @@ static void create_arglist(struct symbol *sym, int count)
 static void init_preprocessor(void)
 {
 	int i;
-	int stream = init_stream("preprocessor", -1, includepath);
+	int stream = init_stream("preprocessor", -1, includepath, -1);
 	static struct {
 		const char *name;
 		int (*handler)(struct stream *, struct token **, struct token *);
diff --git a/symbol.c b/symbol.c
index c0ca79e4..2cc9f82d 100644
--- a/symbol.c
+++ b/symbol.c
@@ -776,7 +776,7 @@ struct symbol	zero_int;
 
 void init_symbols(void)
 {
-	int stream = init_stream("builtin", -1, includepath);
+	int stream = init_stream("builtin", -1, includepath, -1);
 
 #define __IDENT(n,str,res) \
 	hash_ident(&n)
diff --git a/token.h b/token.h
index c5fdf3d0..6d2b0b65 100644
--- a/token.h
+++ b/token.h
@@ -49,7 +49,7 @@ enum constantfile {
 extern const char *includepath[];
 
 struct stream {
-	int fd;
+	int fd, prev;
 	const char *name;
 	const char *path;    // input-file path - see set_stream_include_path()
 	const char **next_path;
@@ -214,7 +214,8 @@ static inline struct token *containing_token(struct token **p)
 extern struct token eof_token_entry;
 #define eof_token(x) ((x) == &eof_token_entry)
 
-extern int init_stream(const char *, int fd, const char **next_path);
+extern int init_stream(const char *, int fd, const char **next_path, int prev_stream);
+extern int stream_prev(int stream);
 extern const char *stream_name(int stream);
 extern struct ident *hash_ident(struct ident *);
 extern struct ident *built_in_ident(const char *);
@@ -224,7 +225,7 @@ extern const char *show_ident(const struct ident *);
 extern const char *show_string(const struct string *string);
 extern const char *show_token(const struct token *);
 extern const char *quote_token(const struct token *);
-extern struct token * tokenize(const char *, int, struct token *, const char **next_path);
+extern struct token * tokenize(const char *, int, int, struct token *, const char **next_path);
 extern struct token * tokenize_buffer(void *, unsigned long, struct token **);
 
 extern void show_identifier_stats(void);
diff --git a/tokenize.c b/tokenize.c
index d3371e1e..c5ba6e6b 100644
--- a/tokenize.c
+++ b/tokenize.c
@@ -62,6 +62,13 @@ const char *stream_name(int stream)
 	return input_streams[stream].name;
 }
 
+int stream_prev(int stream)
+{
+	if (stream < 0 || stream > input_stream_nr)
+		return -1;
+	return input_streams[stream].prev;
+}
+
 static struct position stream_pos(stream_t *stream)
 {
 	struct position pos;
@@ -300,7 +307,7 @@ int *hash_stream(const char *name)
 	return input_stream_hashes + hash;
 }
 
-int init_stream(const char *name, int fd, const char **next_path)
+int init_stream(const char *name, int fd, const char **next_path, int prev_stream)
 {
 	int stream = input_stream_nr, *hash;
 	struct stream *current;
@@ -319,6 +326,7 @@ int init_stream(const char *name, int fd, const char **next_path)
 	current->next_path = next_path;
 	current->path = NULL;
 	current->constant = CONSTANT_FILE_MAYBE;
+	current->prev = prev_stream;
 	input_stream_nr = stream+1;
 	hash = hash_stream(name);
 	current->next_stream = *hash;
@@ -1006,14 +1014,14 @@ struct token * tokenize_buffer(void *buffer, unsigned long size, struct token **
 	return begin;
 }
 
-struct token * tokenize(const char *name, int fd, struct token *endtoken, const char **next_path)
+struct token * tokenize(const char *name, int fd, int prev_stream, struct token *endtoken, const char **next_path)
 {
 	struct token *begin, *end;
 	stream_t stream;
 	unsigned char buffer[BUFSIZE];
 	int idx;
 
-	idx = init_stream(name, fd, next_path);
+	idx = init_stream(name, fd, next_path, prev_stream);
 	if (idx < 0) {
 		// info(endtoken->pos, "File %s is const", name);
 		return endtoken;
diff --git a/validation/cast-kinds-check.c b/validation/cast-kinds-check.c
index 0c0cd673..32a106d4 100644
--- a/validation/cast-kinds-check.c
+++ b/validation/cast-kinds-check.c
@@ -6,6 +6,7 @@
  * check-assert: sizeof(long) == 8
  *
  * check-error-start
+cast-kinds-check.c: note: in included file:
 optim/cast-kinds.c:5:45: warning: cast drops bits
 optim/cast-kinds.c:6:47: warning: cast drops bits
 optim/cast-kinds.c:7:46: warning: cast drops bits