Avoid re-expanding a macro name that has once been rejected from expansion.

The specification of the preprocessor in C99 says that when we see a
macro name that we are already expanding that we refuse to expand it
now, (which we've done for a while), but also that we refuse to ever
expand it later if seen in other contexts at which it would be
legitimate to expand.

We add a test case for that here, and fix it to work. The fix takes
advantage of a new token_t value for tokens and argument words along
with the recently added IDENTIFIER_FINALIZED token type which
instructs the parser to not even look for another expansion.

diff --git a/glcpp-lex.l b/glcpp-lex.l
index aec967964b06c3effc444720526542a73ecc05ef..8e3ab661e6fb5a3498055876864e96f20fc9d049 100644 (file)
--- a/glcpp-lex.l
+++ b/glcpp-lex.l
@@ -114,12 +114,14 @@ TOKEN             [^[:space:](),]+
 <ST_DEFINE_PARAMETER>{HSPACE}+
 
 <ST_DEFINE_VALUE>{TOKEN} {
-       yylval.str = xtalloc_strdup (yyextra, yytext);
+       yylval.token.type = TOKEN;
+       yylval.token.value = xtalloc_strdup (yyextra, yytext);
        return TOKEN;
 }
 
 <ST_DEFINE_VALUE>[(),] {
-       yylval.str = xtalloc_strdup (yyextra, yytext);
+       yylval.token.type = TOKEN;
+       yylval.token.value = xtalloc_strdup (yyextra, yytext);
        return TOKEN;
 }
 
@@ -147,6 +149,9 @@ TOKEN               [^[:space:](),]+
                case TOKEN_CLASS_IDENTIFIER:
                        return IDENTIFIER;
                break;
+               case TOKEN_CLASS_IDENTIFIER_FINALIZED:
+                       return IDENTIFIER_FINALIZED;
+               break;
                case TOKEN_CLASS_FUNC_MACRO:
                        return FUNC_MACRO;
                break;
@@ -162,7 +167,8 @@ TOKEN               [^[:space:](),]+
 }
 
 {TOKEN} {
-       yylval.str = xtalloc_strdup (yyextra, yytext);
+       yylval.token.type = TOKEN;
+       yylval.token.value = xtalloc_strdup (yyextra, yytext);
        return TOKEN;
 }
 

diff --git a/glcpp-parse.y b/glcpp-parse.y
index c8d1919d9c58cb44000dfd21ae783982f42812c3..28e79ebf9f781db648c2614c44e34fb33c97e08d 100644 (file)
--- a/glcpp-parse.y
+++ b/glcpp-parse.y
@@ -108,16 +108,18 @@ glcpp_parser_lex (glcpp_parser_t *parser);
        char *str;
        argument_list_t *argument_list;
        string_list_t *string_list;
+       token_t token;
        token_list_t *token_list;
 }
 
 %parse-param {glcpp_parser_t *parser}
 %lex-param {glcpp_parser_t *parser}
 
-%token DEFINE FUNC_MACRO IDENTIFIER OBJ_MACRO NEWLINE SPACE TOKEN UNDEF
-%type <str> argument_word FUNC_MACRO IDENTIFIER OBJ_MACRO TOKEN
+%token DEFINE FUNC_MACRO IDENTIFIER IDENTIFIER_FINALIZED OBJ_MACRO NEWLINE SPACE TOKEN UNDEF
+%type <str> FUNC_MACRO IDENTIFIER IDENTIFIER_FINALIZED OBJ_MACRO
 %type <argument_list> argument_list
 %type <string_list> macro parameter_list
+%type <token> TOKEN argument_word
 %type <token_list> argument replacement_list pp_tokens
 
 /* Hard to remove shift/reduce conflicts documented as follows:
@@ -145,10 +147,14 @@ content:
                printf ("%s", $1);
                talloc_free ($1);
        }
-|      TOKEN {
+|      IDENTIFIER_FINALIZED {
                printf ("%s", $1);
                talloc_free ($1);
        }
+|      TOKEN {
+               printf ("%s", $1.value);
+               talloc_free ($1.value);
+       }
 |      FUNC_MACRO {
                printf ("%s", $1);
                talloc_free ($1);
@@ -189,11 +195,11 @@ argument_list:
 argument:
        argument_word {
                $$ = _token_list_create (parser);
-               _token_list_append ($$, IDENTIFIER, $1);
+               _token_list_append ($$, $1.type, $1.value);
        }
 |      argument argument_word {
-               _token_list_append ($1, IDENTIFIER, $2);
-               talloc_free ($2);
+               _token_list_append ($1, $2.type, $2.value);
+               talloc_free ($2.value);
                $$ = $1;
        }
 |      argument '(' argument ')' {
@@ -205,10 +211,11 @@ argument:
 ;
 
 argument_word:
-       IDENTIFIER { $$ = $1; }
+       IDENTIFIER { $$.type = IDENTIFIER; $$.value = $1; }
+|      IDENTIFIER_FINALIZED { $$.type = IDENTIFIER_FINALIZED; $$.value = $1; }
 |      TOKEN { $$ = $1; }
-|      FUNC_MACRO { $$ = $1; }
-|      macro { $$ = xtalloc_strdup (parser, ""); }
+|      FUNC_MACRO { $$.type = FUNC_MACRO; $$.value = $1; }
+|      macro { $$.type = TOKEN; $$.value = xtalloc_strdup (parser, ""); }
 ;
 
 
@@ -265,10 +272,10 @@ replacement_list:
 pp_tokens:
        TOKEN {
                $$ = _token_list_create (parser);
-               _token_list_append ($$, TOKEN, $1);
+               _token_list_append ($$, $1.type, $1.value);
        }
 |      pp_tokens TOKEN {
-       _token_list_append ($1, TOKEN, $2);
+       _token_list_append ($1, $2.type, $2.value);
                $$ = $1;
        }
 ;
@@ -567,7 +574,7 @@ glcpp_parser_classify_token (glcpp_parser_t *parser,
        /* Don't consider this a macro if we are already actively
         * expanding this macro. */
        if (glcpp_parser_is_expanding (parser, identifier))
-               return TOKEN_CLASS_IDENTIFIER;
+               return TOKEN_CLASS_IDENTIFIER_FINALIZED;
 
        /* Definitely a macro. Just need to check if it's function-like. */
        if (macro->is_function)
@@ -741,6 +748,10 @@ glcpp_parser_lex (glcpp_parser_t *parser)
 
        yylval.str = xtalloc_strdup (parser, replacements->value);
 
+       /* Carefully refuse to expand any finalized identifier. */
+       if (replacements->type == IDENTIFIER_FINALIZED)
+               return IDENTIFIER_FINALIZED;
+
        switch (glcpp_parser_classify_token (parser, yylval.str,
                                             &parameter_index))
        {
@@ -753,6 +764,9 @@ glcpp_parser_lex (glcpp_parser_t *parser)
        case TOKEN_CLASS_IDENTIFIER:
                return IDENTIFIER;
                break;
+       case TOKEN_CLASS_IDENTIFIER_FINALIZED:
+               return IDENTIFIER_FINALIZED;
+               break;
        case TOKEN_CLASS_FUNC_MACRO:
                return FUNC_MACRO;
                break;

diff --git a/glcpp.h b/glcpp.h
index c647e2a72e11513e66d97310ad8c970e99b84be5..5432a3181736a22f80b43f9dd02ee7be23de1aa0 100644 (file)
--- a/glcpp.h
+++ b/glcpp.h
@@ -42,6 +42,11 @@ typedef struct string_list {
        string_node_t *tail;
 } string_list_t;
 
+typedef struct token {
+       int type;
+       char *value;
+} token_t;
+
 typedef struct token_node {
        int type;
        const char *value;
@@ -68,6 +73,7 @@ typedef struct glcpp_parser glcpp_parser_t;
 typedef enum {
        TOKEN_CLASS_ARGUMENT,
        TOKEN_CLASS_IDENTIFIER,
+       TOKEN_CLASS_IDENTIFIER_FINALIZED,
        TOKEN_CLASS_FUNC_MACRO,
        TOKEN_CLASS_OBJ_MACRO
 } token_class_t;

diff --git a/tests/037-finalize-unexpanded-macro.c b/tests/037-finalize-unexpanded-macro.c
new file mode 100644 (file)
index 0000000..b3a2f37
--- /dev/null
+++ b/tests/037-finalize-unexpanded-macro.c
@@ -0,0 +1,3 @@
+#define expand(x) expand(x once)
+#define foo(x) x
+foo(expand(just))