gcc/rust/parse/rust-parse.cc

   1 /* This file is part of GCC.
   2
   3 GCC is free software; you can redistribute it and/or modify
   4 it under the terms of the GNU General Public License as published by
   5 the Free Software Foundation; either version 3, or (at your option)
   6 any later version.
   7
   8 GCC is distributed in the hope that it will be useful,
   9 but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 GNU General Public License for more details.
  12
  13 You should have received a copy of the GNU General Public License
  14 along with GCC; see the file COPYING3.  If not see
  15 <http://www.gnu.org/licenses/>. */
  16
  17 #include "rust-parse.h"
  18 #include "rust-linemap.h"
  19 #include "rust-diagnostics.h"
  20
  21 namespace Rust {
  22
  23 std::string
  24 extract_module_path (const AST::AttrVec &inner_attrs,
  25                      const AST::AttrVec &outer_attrs, const std::string &name)
  26 {
  27   AST::Attribute path_attr = AST::Attribute::create_empty ();
  28   for (const auto &attr : inner_attrs)
  29     {
  30       if (attr.get_path ().as_string () == "path")
  31         {
  32           path_attr = attr;
  33           break;
  34         }
  35     }
  36
  37   // Here, we found a path attribute, but it has no associated string. This is
  38   // invalid
  39   if (!path_attr.is_empty () && !path_attr.has_attr_input ())
  40     {
  41       rust_error_at (
  42         path_attr.get_locus (),
  43         // Split the format string so that -Wformat-diag does not complain...
  44         "path attributes must contain a filename: '%s'", "#![path = \"file\"]");
  45       return name;
  46     }
  47
  48   for (const auto &attr : outer_attrs)
  49     {
  50       if (attr.get_path ().as_string () == "path")
  51         {
  52           path_attr = attr;
  53           break;
  54         }
  55     }
  56
  57   // We didn't find a path attribute. This is not an error, there simply isn't
  58   // one present
  59   if (path_attr.is_empty ())
  60     return name;
  61
  62   // Here, we found a path attribute, but it has no associated string. This is
  63   // invalid
  64   if (!path_attr.has_attr_input ())
  65     {
  66       rust_error_at (
  67         path_attr.get_locus (),
  68         // Split the format string so that -Wformat-diag does not complain...
  69         "path attributes must contain a filename: '%s'", "#[path = \"file\"]");
  70       return name;
  71     }
  72
  73   auto path_value = path_attr.get_attr_input ().as_string ();
  74
  75   // At this point, the 'path' is of the following format: '= "<file.rs>"'
  76   // We need to remove the equal sign and only keep the actual filename.
  77   // In order to do this, we can simply go through the string until we find
  78   // a character that is not an equal sign or whitespace
  79   auto filename_begin = path_value.find_first_not_of ("=\t ");
  80
  81   auto path = path_value.substr (filename_begin);
  82
  83   // On windows, the path might mix '/' and '\' separators. Replace the
  84   // UNIX-like separators by MSDOS separators to make sure the path will resolve
  85   // properly.
  86   //
  87   // Source: rustc compiler
  88   // (https://github.com/rust-lang/rust/blob/9863bf51a52b8e61bcad312f81b5193d53099f9f/compiler/rustc_expand/src/module.rs#L174)
  89 #if defined(HAVE_DOS_BASED_FILE_SYSTEM)
  90   path.replace ('/', '\\');
  91 #endif /* HAVE_DOS_BASED_FILE_SYSTEM */
  92
  93   return path;
  94 }
  95
  96 template <typename T>
  97 static bool
  98 contains (std::vector<T> &vec, T elm)
  99 {
 100   return std::find (vec.begin (), vec.end (), elm) != vec.end ();
 101 }
 102
 103 /**
 104  * Avoid UB by calling .front() and .back() on empty containers...
 105  */
 106
 107 template <typename T>
 108 static const T *
 109 get_back_ptr (const std::vector<std::unique_ptr<T>> &values)
 110 {
 111   if (values.empty ())
 112     return nullptr;
 113
 114   return values.back ().get ();
 115 }
 116
 117 template <typename T>
 118 static const T *
 119 get_front_ptr (const std::vector<std::unique_ptr<T>> &values)
 120 {
 121   if (values.empty ())
 122     return nullptr;
 123
 124   return values.front ().get ();
 125 }
 126
 127 static bool
 128 peculiar_fragment_match_compatible_fragment (
 129   const AST::MacroFragSpec &last_spec, const AST::MacroFragSpec &spec,
 130   Location match_locus)
 131 {
 132   static std::unordered_map<AST::MacroFragSpec::Kind,
 133                             std::vector<AST::MacroFragSpec::Kind>>
 134     fragment_follow_set
 135     = {{AST::MacroFragSpec::PATH, {AST::MacroFragSpec::BLOCK}},
 136        {AST::MacroFragSpec::TY, {AST::MacroFragSpec::BLOCK}},
 137        {AST::MacroFragSpec::VIS,
 138         {AST::MacroFragSpec::IDENT, AST::MacroFragSpec::TY,
 139          AST::MacroFragSpec::PATH}}};
 140
 141   auto is_valid
 142     = contains (fragment_follow_set[last_spec.get_kind ()], spec.get_kind ());
 143
 144   if (!is_valid)
 145     rust_error_at (
 146       match_locus,
 147       "fragment specifier %<%s%> is not allowed after %<%s%> fragments",
 148       spec.as_string ().c_str (), last_spec.as_string ().c_str ());
 149
 150   return is_valid;
 151 }
 152
 153 static bool
 154 peculiar_fragment_match_compatible (const AST::MacroMatchFragment &last_match,
 155                                     const AST::MacroMatch &match)
 156 {
 157   static std::unordered_map<AST::MacroFragSpec::Kind, std::vector<TokenId>>
 158     follow_set
 159     = {{AST::MacroFragSpec::EXPR, {MATCH_ARROW, COMMA, SEMICOLON}},
 160        {AST::MacroFragSpec::STMT, {MATCH_ARROW, COMMA, SEMICOLON}},
 161        {AST::MacroFragSpec::PAT, {MATCH_ARROW, COMMA, EQUAL, PIPE, IF, IN}},
 162        {AST::MacroFragSpec::PATH,
 163         {MATCH_ARROW, COMMA, EQUAL, PIPE, SEMICOLON, COLON, RIGHT_ANGLE,
 164          RIGHT_SHIFT, LEFT_SQUARE, LEFT_CURLY, AS, WHERE}},
 165        {AST::MacroFragSpec::TY,
 166         {MATCH_ARROW, COMMA, EQUAL, PIPE, SEMICOLON, COLON, RIGHT_ANGLE,
 167          RIGHT_SHIFT, LEFT_SQUARE, LEFT_CURLY, AS, WHERE}},
 168        {AST::MacroFragSpec::VIS,
 169         {
 170           COMMA,
 171           IDENTIFIER /* FIXME: Other than `priv` */,
 172           LEFT_PAREN,
 173           LEFT_SQUARE,
 174           EXCLAM,
 175           ASTERISK,
 176           AMP,
 177           LOGICAL_AND,
 178           QUESTION_MARK,
 179           LIFETIME,
 180           LEFT_ANGLE,
 181           LEFT_SHIFT,
 182           SUPER,
 183           SELF,
 184           SELF_ALIAS,
 185           EXTERN_TOK,
 186           CRATE,
 187           UNDERSCORE,
 188           FOR,
 189           IMPL,
 190           FN_TOK,
 191           UNSAFE,
 192           TYPEOF,
 193           DYN
 194           // FIXME: Add Non kw identifiers
 195           // FIXME: Add $crate as valid
 196         }}};
 197
 198   Location error_locus = match.get_match_locus ();
 199   std::string kind_str = "fragment";
 200   auto &allowed_toks = follow_set[last_match.get_frag_spec ().get_kind ()];
 201
 202   // There are two behaviors to handle here: If the follow-up match is a token,
 203   // we want to check if it is allowed.
 204   // If it is a fragment, repetition or matcher then we know that it will be
 205   // an error.
 206   // For repetitions and matchers we want to extract a proper location to report
 207   // the error.
 208   switch (match.get_macro_match_type ())
 209     {
 210       case AST::MacroMatch::Tok: {
 211         auto tok = static_cast<const AST::Token *> (&match);
 212         if (contains (allowed_toks, tok->get_id ()))
 213           return true;
 214         kind_str = "token `"
 215                    + std::string (get_token_description (tok->get_id ())) + "`";
 216         error_locus = tok->get_match_locus ();
 217         break;
 218       }
 219       break;
 220       case AST::MacroMatch::Repetition: {
 221         auto repetition
 222           = static_cast<const AST::MacroMatchRepetition *> (&match);
 223         auto &matches = repetition->get_matches ();
 224         auto first_frag = get_front_ptr (matches);
 225         if (first_frag)
 226           return peculiar_fragment_match_compatible (last_match, *first_frag);
 227         break;
 228       }
 229       case AST::MacroMatch::Matcher: {
 230         auto matcher = static_cast<const AST::MacroMatcher *> (&match);
 231         auto first_token = matcher->get_delim_type ();
 232         TokenId delim_id;
 233         switch (first_token)
 234           {
 235           case AST::PARENS:
 236             delim_id = LEFT_PAREN;
 237             break;
 238           case AST::SQUARE:
 239             delim_id = LEFT_SQUARE;
 240             break;
 241           case AST::CURLY:
 242             delim_id = LEFT_CURLY;
 243             break;
 244           default:
 245             gcc_unreachable ();
 246             break;
 247           }
 248         if (contains (allowed_toks, delim_id))
 249           return true;
 250         kind_str = "token `" + std::string (get_token_description (delim_id))
 251                    + "` at start of matcher";
 252         error_locus = matcher->get_match_locus ();
 253         break;
 254       }
 255       case AST::MacroMatch::Fragment: {
 256         auto last_spec = last_match.get_frag_spec ();
 257         auto fragment = static_cast<const AST::MacroMatchFragment *> (&match);
 258         if (last_spec.has_follow_set_fragment_restrictions ())
 259           return peculiar_fragment_match_compatible_fragment (
 260             last_spec, fragment->get_frag_spec (), match.get_match_locus ());
 261       }
 262       break;
 263     }
 264
 265   rust_error_at (error_locus, "%s is not allowed after %<%s%> fragment",
 266                  kind_str.c_str (),
 267                  last_match.get_frag_spec ().as_string ().c_str ());
 268   auto allowed_toks_str
 269     = "`" + std::string (get_token_description (allowed_toks[0])) + "`";
 270   for (size_t i = 1; i < allowed_toks.size (); i++)
 271     allowed_toks_str
 272       += ", `" + std::string (get_token_description (allowed_toks[i])) + "`";
 273
 274   rust_inform (error_locus, "allowed tokens are %s", allowed_toks_str.c_str ());
 275
 276   return false;
 277 }
 278
 279 bool
 280 is_match_compatible (const AST::MacroMatch &last_match,
 281                      const AST::MacroMatch &match)
 282 {
 283   const AST::MacroMatch *new_last = nullptr;
 284
 285   // We want to "extract" the concerning matches. In cases such as matchers and
 286   // repetitions, we actually store multiple matchers, but are only concerned
 287   // about the follow-set ambiguities of certain elements.
 288   // There are some cases where we can short-circuit the algorithm: There will
 289   // never be restrictions on token literals, or on certain fragments which do
 290   // not have a set of follow-restrictions.
 291
 292   switch (last_match.get_macro_match_type ())
 293     {
 294       // This is our main stop condition: When we are finally looking at the
 295       // last match (or its actual last component), and it is a fragment, it
 296       // may contain some follow up restrictions.
 297       case AST::MacroMatch::Fragment: {
 298         auto fragment
 299           = static_cast<const AST::MacroMatchFragment *> (&last_match);
 300         if (fragment->get_frag_spec ().has_follow_set_restrictions ())
 301           return peculiar_fragment_match_compatible (*fragment, match);
 302         else
 303           return true;
 304       }
 305       case AST::MacroMatch::Repetition: {
 306         // A repetition on the left hand side means we want to make sure the
 307         // last match of the repetition is compatible with the new match
 308         auto repetition
 309           = static_cast<const AST::MacroMatchRepetition *> (&last_match);
 310         new_last = get_back_ptr (repetition->get_matches ());
 311         // If there are no matches in the matcher, then it can be followed by
 312         // anything
 313         if (!new_last)
 314           return true;
 315         break;
 316       }
 317     case AST::MacroMatch::Matcher:
 318     case AST::MacroMatch::Tok:
 319       return true;
 320     }
 321
 322   rust_assert (new_last);
 323
 324   // We check recursively until we find a terminating condition
 325   // FIXME: Does expansion depth/limit matter here?
 326   return is_match_compatible (*new_last, match);
 327 }
 328 } // namespace Rust