From 58e79539fcf51bbaf7284f948cfd216c2076a815 Mon Sep 17 00:00:00 2001 From: Akim Demaille Date: Wed, 15 Apr 2020 07:38:46 +0200 Subject: [PATCH] c: don't emit an error message when the scanner returns YYERRCODE * data/skeletons/yacc.c (yyparse): When the scanner returns YYERRCODE, go directly to error recovery (yyerrlab1). However, don't keep the error token as lookahead, that token is too special. * data/skeletons/lalr1.cc: Likewise. * examples/c/bistromathic/parse.y (yylex): Use that feature to report nicely invalid characters. * examples/c/bistromathic/bistromathic.test: Check that. * examples/test: Neutralize gratuitous differences such as rule position. * tests/calc.at: Check that case in C only. The other case seem to be working, but that's an illusion that the next commit will address (in fact, they can enter endless loops, and report the error several times anyway). --- data/skeletons/lalr1.cc | 10 ++ data/skeletons/yacc.c | 11 ++ examples/c/bistromathic/bistromathic.test | 122 +++++++++++++++++++++- examples/c/bistromathic/parse.y | 26 +++-- examples/test | 21 ++-- tests/calc.at | 46 ++++++-- 6 files changed, 214 insertions(+), 22 deletions(-) diff --git a/data/skeletons/lalr1.cc b/data/skeletons/lalr1.cc index 99c64331..cdf42c6c 100644 --- a/data/skeletons/lalr1.cc +++ b/data/skeletons/lalr1.cc @@ -981,6 +981,16 @@ b4_dollar_popdef])[]dnl } YY_SYMBOL_PRINT ("Next token is", yyla); + if (yyla.kind () == ]symbol_kind::b4_symbol(1, kind)[) + { + // The scanner already issued an error message, process directly + // to error recovery. But do not keep the error token as + // lookahead, it is too special and may lead us to an endless + // loop in error recovery. */ + yyla.type = ]symbol_kind::b4_symbol(2, kind)[; + goto yyerrlab1; + } + /* If the proper action on seeing token YYLA.TYPE is to reduce or to detect an error, take that action. */ yyn += yyla.kind (); diff --git a/data/skeletons/yacc.c b/data/skeletons/yacc.c index 1ac8e9bc..f7a12dc7 100644 --- a/data/skeletons/yacc.c +++ b/data/skeletons/yacc.c @@ -1770,6 +1770,17 @@ yyread_pushed_token:]])[ yytoken = ]b4_symbol(0, [kind])[; YYDPRINTF ((stderr, "Now at end of input.\n")); } + else if (yychar == ]b4_symbol(1, [id])[) + { + /* The scanner already issued an error message, process directly + to error recovery. But do not keep the error token as + lookahead, it is too special and may lead us to an endless + loop in error recovery. */ + yychar = ]b4_symbol(2, [id])[; + yytoken = ]b4_symbol(1, [kind])[;]b4_locations_if([[ + yyerror_range[1] = yylloc;]])[ + goto yyerrlab1; + } else { yytoken = YYTRANSLATE (yychar); diff --git a/examples/c/bistromathic/bistromathic.test b/examples/c/bistromathic/bistromathic.test index 629c32c5..9a5b6d11 100755 --- a/examples/c/bistromathic/bistromathic.test +++ b/examples/c/bistromathic/bistromathic.test @@ -82,7 +82,11 @@ run 0 '> 1 / 0 > '' err: 1.1-5: error: division by zero' -# Error recovery. + +## ---------------- ## +## Error recovery. ## +## ---------------- ## + cat >input <input < () +666 +> '' +err: 1.2: syntax error: expected - or ( or number or function or variable before )' + + cat >input < 100% + 10 -110 > '' -err: 1.4: error: invalid character' +err: 1.4: syntax error: invalid character: %' + +# Traces. This allows to check the location of the error. If we +# forget to map YYERRCODE to YYUNDEF, error recovery enters an endless +# loop with this input. +cat >input < (+_) +666 +> '' +err: Starting parse +err: Entering state 0 +err: Stack now 0 +err: Reading a token +err: Next token is token ( (1.1: ) +err: Shifting token ( (1.1: ) +err: Entering state 2 +err: Stack now 0 2 +err: Return for a new token: +err: Reading a token +err: Next token is token + (1.2: ) +err: LAC: initial context established for + +err: LAC: checking lookahead +: Err +err: LAC: checking lookahead end of file: Err +err: LAC: checking lookahead +: Err +err: LAC: checking lookahead -: S1 +err: LAC: checking lookahead *: Err +err: LAC: checking lookahead /: Err +err: LAC: checking lookahead ^: Err +err: LAC: checking lookahead (: S2 +err: LAC: checking lookahead ): Err +err: LAC: checking lookahead =: Err +err: LAC: checking lookahead exit: Err +err: LAC: checking lookahead number: S4 +err: LAC: checking lookahead function: S5 +err: LAC: checking lookahead variable: S6 +err: LAC: checking lookahead NEG: Err +err: 1.2: syntax error: expected - or ( or number or function or variable before + +err: LAC: initial context discarded due to error recovery +err: Shifting token error (1.2: ) +err: Entering state 10 +err: Stack now 0 2 10 +err: Next token is token + (1.2: ) +err: LAC: initial context established for + +err: LAC: checking lookahead +: Err +err: Error: discarding token + (1.2: ) +err: Error: popping token error (1.2: ) +err: Stack now 0 2 +err: LAC: initial context discarded due to error recovery +err: Shifting token error (1.2: ) +err: Entering state 10 +err: Stack now 0 2 10 +err: Return for a new token: +err: 1.3: syntax error: invalid character: _ +err: Reading a token +err: Error: popping token error (1.2: ) +err: Stack now 0 2 +err: Shifting token error (1.2-3: ) +err: Entering state 10 +err: Stack now 0 2 10 +err: Next token is token invalid token (1.3: ) +err: LAC: initial context established for invalid token +err: LAC: checking lookahead invalid token: Always Err +err: Error: discarding token invalid token (1.3: ) +err: Error: popping token error (1.2-3: ) +err: Stack now 0 2 +err: LAC: initial context discarded due to error recovery +err: Shifting token error (1.2-3: ) +err: Entering state 10 +err: Stack now 0 2 10 +err: Return for a new token: +err: Reading a token +err: Next token is token ) (1.4: ) +err: Shifting token ) (1.4: ) +err: Entering state 20 +err: Stack now 0 2 10 20 +err: Reducing stack by rule 15 (line 151): +err: $1 = token ( (1.1: ) +err: $2 = token error (1.2-3: ) +err: $3 = token ) (1.4: ) +err: -> $$ = nterm exp (1.1-4: 666) +err: Entering state 7 +err: Stack now 0 7 +err: Return for a new token: +err: Reading a token +err: Now at end of input. +err: LAC: initial context established for end of file +err: LAC: checking lookahead end of file: R2 G8 S19 +err: Reducing stack by rule 2 (line 126): +err: $1 = nterm exp (1.1-4: 666) +err: -> $$ = nterm input (1.1-4: ) +err: Entering state 8 +err: Stack now 0 8 +err: Now at end of input. +err: Shifting token end of file (1.5: ) +err: LAC: initial context discarded due to shift +err: Entering state 19 +err: Stack now 0 8 19 +err: Stack now 0 8 19 +err: Cleanup: popping token end of file (1.5: ) +err: Cleanup: popping nterm input (1.1-4: )' -p + ## ------------ ## diff --git a/examples/c/bistromathic/parse.y b/examples/c/bistromathic/parse.y index 5d422651..042c5616 100644 --- a/examples/c/bistromathic/parse.y +++ b/examples/c/bistromathic/parse.y @@ -3,6 +3,7 @@ %code top { #include // isdigit #include // cos, sin, etc. + #include // va_start #include // printf #include // calloc #include // strcmp @@ -45,8 +46,14 @@ } %code provides { +# ifndef __attribute__ +# ifndef __GNUC__ +# define __attribute__(Spec) /* empty */ +# endif +# endif int yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc); - void yyerror (YYLTYPE *yylloc, char const *msg); + void yyerror (YYLTYPE *loc, char const *format, ...) + __attribute__ ((__format__ (__printf__, 2, 3))); } %code { @@ -249,6 +256,8 @@ yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc) case '(': return TOK_LPAREN; case ')': return TOK_RPAREN; + case '!': return TOK_YYUNDEF; + case '\0': return TOK_YYEOF; // Numbers. @@ -290,8 +299,8 @@ yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc) // Stray characters. default: - yyerror (yylloc, "error: invalid character"); - return yylex (line, yylval, yylloc); + yyerror (yylloc, "syntax error: invalid character: %c", c); + return TOK_YYERRCODE; } } @@ -371,10 +380,15 @@ yyreport_syntax_error (const yypcontext_t *ctx) // Called by yyparse on error. -void yyerror (YYLTYPE *loc, char const *msg) +void yyerror (YYLTYPE *loc, char const *format, ...) { YY_LOCATION_PRINT (stderr, *loc); - fprintf (stderr, ": %s\n", msg); + fputs (": ", stderr); + va_list args; + va_start (args, format); + vfprintf (stderr, format, args); + va_end (args); + putc ('\n', stderr); } @@ -535,7 +549,7 @@ int main (int argc, char const* argv[]) #endif // Enable parse traces on option -p. - if (argc == 2 && strcmp (argv[1], "-p") == 0) + if (1 < argc && strcmp (argv[1], "-p") == 0) yydebug = 1; init_table (); init_readline (); diff --git a/examples/test b/examples/test index 044446ec..b4be2dc1 100755 --- a/examples/test +++ b/examples/test @@ -89,11 +89,13 @@ run () shift # Expected output. - if $strip_prompt; then - $echo "$1" | sed -e '/^> /d' >exp - else - $echo "$1" >exp - fi + $echo "$1" | + sed -e 's/Reducing stack by rule .* (line .*):/Reducing stack by rule XX (line XXX):/g' | + if $strip_prompt; then + sed -e '/^> /d' + else + cat + fi >exp shift # Effective exit status. @@ -102,7 +104,14 @@ run () prog "$@" - out_eff 2>err_eff || sta_eff=$? # Combine effective output and error streams. - { cat out_eff && $noerr || sed -e 's/^/err: /g' err_eff; } >eff + { + cat out_eff + if ! $noerr; then + sed -e 's/^/err: /g' \ + -e 's/Reducing stack by rule .* (line .*):/Reducing stack by rule XX (line XXX):/g' \ + err_eff + fi + } >eff if test $sta_eff -eq $sta_exp; then if cmp eff exp 2>/dev/null; then diff --git a/tests/calc.at b/tests/calc.at index 992b911c..a3711612 100644 --- a/tests/calc.at +++ b/tests/calc.at @@ -201,8 +201,8 @@ read_integer (]AT_YYLEX_FORMALS[) /* Skip white spaces. */ do { -]AT_LOCATION_IF( -[ AT_LOC_FIRST_COLUMN = AT_LOC_LAST_COLUMN; +]AT_LOCATION_IF([ + AT_LOC_FIRST_COLUMN = AT_LOC_LAST_COLUMN; AT_LOC_FIRST_LINE = AT_LOC_LAST_LINE; ])[ } @@ -220,6 +220,15 @@ read_integer (]AT_YYLEX_FORMALS[) if (c == EOF) return ]AT_TOKEN_PREFIX[CALC_EOF; + /* An explicit error raised by the scanner. */ + if (c == '#') + {]AT_LOCATION_IF([ + fprintf (stderr, "%d.%d: ", + AT_LOC_FIRST_LINE, AT_LOC_FIRST_COLUMN);])[ + fputs ("syntax error: invalid character: '#'\n", stderr); + return ]AT_TOKEN_PREFIX[]AT_API_PREFIX[ERRCODE; + } + /* Return single chars. */ return c; } @@ -304,7 +313,7 @@ class CalcLexer(R) : Lexer location.end.column += 1;]])[ } - // Handle EOF. + // EOF. if (input.empty) return TokenKind.CALC_EOF; @@ -325,6 +334,14 @@ class CalcLexer(R) : Lexer else location.end.column += 1;]])[ input.popFront; + + // An explicit error raised by the scanner. */ + if (c == '#') + { + stderr.writeln (]AT_LOCATION_IF([location, ": ", ])["syntax error: invalid character: '#'"); + return TokenKind.YYERRCODE; + } + return c; } } @@ -370,9 +387,9 @@ m4_define([AT_CALC_YYLEX(java)], public int yylex () throws IOException {;]AT_LOCATION_IF([[ start.set (reader.getPosition ());]])[ - int ttype = st.nextToken ();]AT_LOCATION_IF([[ + int tkind = st.nextToken ();]AT_LOCATION_IF([[ end.set (reader.getPosition ());]])[ - switch (ttype) + switch (tkind) { case StreamTokenizer.TT_EOF: return EOF; @@ -386,8 +403,11 @@ m4_define([AT_CALC_YYLEX(java)], return NUM; case ' ': case '\t': return yylex (); + case '#': + System.err.println(]AT_LOCATION_IF([[start + ": " + ]])["syntax error: invalid character: '#'"); + return YYERRCODE; default: - return ttype; + return tkind; } } ]AT_LEXPARAM_IF([], [[}]])[ @@ -1004,6 +1024,20 @@ _AT_CHECK_CALC_ERROR([$1], [0], [(* *) + (*) + (*)], ]AT_JAVA_IF([1.10-1.11], [1.10])[: syntax error on token ['*'] (expected: [number] ['-'] ['('] ['!']) ]AT_JAVA_IF([1.16-1.17], [1.16])[: syntax error on token ['*'] (expected: [number] ['-'] ['('] ['!'])]]) + +# YYERRCODE. +# --------- +# Check that returning YYERRCODE from the scanner properly enters +# error-recovery without issuing a second error message. + +_AT_CHECK_CALC_ERROR([$1], [0], [(#) + (#) = 2222], + [[final: 2222 0 0]], + [102], +[[1.2: syntax error: invalid character: '#' +1.8: syntax error: invalid character: '#']]) + + + AT_BISON_OPTION_POPDEFS AT_CLEANUP