gcc/tree-diagnostic.c

   1 /* Language-independent diagnostic subroutines for the GNU Compiler
   2    Collection that are only for use in the compilers proper and not
   3    the driver or other programs.
   4    Copyright (C) 1999-2017 Free Software Foundation, Inc.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tree.h"
  26 #include "diagnostic.h"
  27 #include "tree-pretty-print.h"
  28 #include "tree-diagnostic.h"
  29 #include "dumpfile.h" /* TDF_DIAGNOSTIC */
  30 #include "langhooks.h"
  31 #include "intl.h"
  32
  33 /* Prints out, if necessary, the name of the current function
  34    that caused an error.  Called from all error and warning functions.  */
  35 void
  36 diagnostic_report_current_function (diagnostic_context *context,
  37                                     diagnostic_info *diagnostic)
  38 {
  39   diagnostic_report_current_module (context, diagnostic_location (diagnostic));
  40   lang_hooks.print_error_function (context, LOCATION_FILE (input_location),
  41                                    diagnostic);
  42 }
  43
  44 static void
  45 default_tree_diagnostic_starter (diagnostic_context *context,
  46                                  diagnostic_info *diagnostic)
  47 {
  48   diagnostic_report_current_function (context, diagnostic);
  49   pp_set_prefix (context->printer, diagnostic_build_prefix (context,
  50                                                             diagnostic));
  51 }
  52
  53 /* This is a pair made of a location and the line map it originated
  54    from.  It's used in the maybe_unwind_expanded_macro_loc function
  55    below.  */
  56 struct loc_map_pair
  57 {
  58   const line_map_macro *map;
  59   source_location where;
  60 };
  61
  62
  63 /* Unwind the different macro expansions that lead to the token which
  64    location is WHERE and emit diagnostics showing the resulting
  65    unwound macro expansion trace.  Let's look at an example to see how
  66    the trace looks like.  Suppose we have this piece of code,
  67    artificially annotated with the line numbers to increase
  68    legibility:
  69
  70     $ cat -n test.c
  71       1    #define OPERATE(OPRD1, OPRT, OPRD2) \
  72       2      OPRD1 OPRT OPRD2;
  73       3
  74       4    #define SHIFTL(A,B) \
  75       5      OPERATE (A,<<,B)
  76       6
  77       7    #define MULT(A) \
  78       8      SHIFTL (A,1)
  79       9
  80      10    void
  81      11    g ()
  82      12    {
  83      13      MULT (1.0);// 1.0 << 1; <-- so this is an error.
  84      14    }
  85
  86    Here is the diagnostic that we want the compiler to generate:
  87
  88     test.c: In function ‘g’:
  89     test.c:5:14: error: invalid operands to binary << (have ‘double’ and ‘int’)
  90     test.c:2:9: note: in definition of macro 'OPERATE'
  91     test.c:8:3: note: in expansion of macro 'SHIFTL'
  92     test.c:13:3: note: in expansion of macro 'MULT'
  93
  94    The part that goes from the third to the fifth line of this
  95    diagnostic (the lines containing the 'note:' string) is called the
  96    unwound macro expansion trace.  That's the part generated by this
  97    function.  */
  98
  99 static void
 100 maybe_unwind_expanded_macro_loc (diagnostic_context *context,
 101                                  const diagnostic_info *diagnostic,
 102                                  source_location where)
 103 {
 104   const struct line_map *map;
 105   auto_vec<loc_map_pair> loc_vec;
 106   unsigned ix;
 107   loc_map_pair loc, *iter;
 108
 109   map = linemap_lookup (line_table, where);
 110   if (!linemap_macro_expansion_map_p (map))
 111     return;
 112
 113   /* Let's unwind the macros that got expanded and led to the token
 114      which location is WHERE.  We are going to store these macros into
 115      LOC_VEC, so that we can later walk it at our convenience to
 116      display a somewhat meaningful trace of the macro expansion
 117      history to the user.  Note that the first macro of the trace
 118      (which is OPERATE in the example above) is going to be stored at
 119      the beginning of LOC_VEC.  */
 120
 121   do
 122     {
 123       loc.where = where;
 124       loc.map = linemap_check_macro (map);
 125
 126       loc_vec.safe_push (loc);
 127
 128       /* WHERE is the location of a token inside the expansion of a
 129          macro.  MAP is the map holding the locations of that macro
 130          expansion.  Let's get the location of the token inside the
 131          context that triggered the expansion of this macro.
 132          This is basically how we go "down" in the trace of macro
 133          expansions that led to WHERE.  */
 134       where = linemap_unwind_toward_expansion (line_table, where, &map);
 135     } while (linemap_macro_expansion_map_p (map));
 136
 137   /* Now map is set to the map of the location in the source that
 138      first triggered the macro expansion.  This must be an ordinary map.  */
 139   const line_map_ordinary *ord_map = linemap_check_ordinary (map);
 140
 141   /* Walk LOC_VEC and print the macro expansion trace, unless the
 142      first macro which expansion triggered this trace was expanded
 143      inside a system header.  */
 144   int saved_location_line =
 145     expand_location_to_spelling_point (diagnostic_location (diagnostic)).line;
 146
 147   if (!LINEMAP_SYSP (ord_map))
 148     FOR_EACH_VEC_ELT (loc_vec, ix, iter)
 149       {
 150         /* Sometimes, in the unwound macro expansion trace, we want to
 151            print a part of the context that shows where, in the
 152            definition of the relevant macro, is the token (we are
 153            looking at) used.  That is the case in the introductory
 154            comment of this function, where we print:
 155
 156                test.c:2:9: note: in definition of macro 'OPERATE'.
 157
 158            We print that "macro definition context" because the
 159            diagnostic line (emitted by the call to
 160            pp_ouput_formatted_text in diagnostic_report_diagnostic):
 161
 162                test.c:5:14: error: invalid operands to binary << (have ‘double’ and ‘int’)
 163
 164            does not point into the definition of the macro where the
 165            token '<<' (that is an argument to the function-like macro
 166            OPERATE) is used.  So we must "display" the line of that
 167            macro definition context to the user somehow.
 168
 169            A contrario, when the first interesting diagnostic line
 170            points into the definition of the macro, we don't need to
 171            display any line for that macro definition in the trace
 172            anymore, otherwise it'd be redundant.  */
 173
 174         /* Okay, now here is what we want.  For each token resulting
 175            from macro expansion we want to show: 1/ where in the
 176            definition of the macro the token comes from; 2/ where the
 177            macro got expanded.  */
 178
 179         /* Resolve the location iter->where into the locus 1/ of the
 180            comment above.  */
 181         source_location resolved_def_loc =
 182           linemap_resolve_location (line_table, iter->where,
 183                                     LRK_MACRO_DEFINITION_LOCATION, NULL);
 184
 185         /* Don't print trace for locations that are reserved or from
 186            within a system header.  */
 187         const line_map_ordinary *m = NULL;
 188         source_location l =
 189           linemap_resolve_location (line_table, resolved_def_loc,
 190                                     LRK_SPELLING_LOCATION,  &m);
 191         if (l < RESERVED_LOCATION_COUNT || LINEMAP_SYSP (m))
 192           continue;
 193
 194         /* We need to print the context of the macro definition only
 195            when the locus of the first displayed diagnostic (displayed
 196            before this trace) was inside the definition of the
 197            macro.  */
 198         int resolved_def_loc_line = SOURCE_LINE (m, l);
 199         if (ix == 0 && saved_location_line != resolved_def_loc_line)
 200           {
 201             diagnostic_append_note (context, resolved_def_loc,
 202                                     "in definition of macro %qs",
 203                                     linemap_map_get_macro_name (iter->map));
 204             /* At this step, as we've printed the context of the macro
 205                definition, we don't want to print the context of its
 206                expansion, otherwise, it'd be redundant.  */
 207             continue;
 208           }
 209
 210         /* Resolve the location of the expansion point of the macro
 211            which expansion gave the token represented by def_loc.
 212            This is the locus 2/ of the earlier comment.  */
 213         source_location resolved_exp_loc =
 214           linemap_resolve_location (line_table,
 215                                     MACRO_MAP_EXPANSION_POINT_LOCATION (iter->map),
 216                                     LRK_MACRO_DEFINITION_LOCATION, NULL);
 217
 218         diagnostic_append_note (context, resolved_exp_loc,
 219                                 "in expansion of macro %qs",
 220                                 linemap_map_get_macro_name (iter->map));
 221       }
 222 }
 223
 224 /*  This is a diagnostic finalizer implementation that is aware of
 225     virtual locations produced by libcpp.
 226
 227     It has to be called by the diagnostic finalizer of front ends that
 228     uses libcpp and wish to get diagnostics involving tokens resulting
 229     from macro expansion.
 230
 231     For a given location, if said location belongs to a token
 232     resulting from a macro expansion, this starter prints the context
 233     of the token.  E.g, for multiply nested macro expansion, it
 234     unwinds the nested macro expansions and prints them in a manner
 235     that is similar to what is done for function call stacks, or
 236     template instantiation contexts.  */
 237 void
 238 virt_loc_aware_diagnostic_finalizer (diagnostic_context *context,
 239                                      diagnostic_info *diagnostic)
 240 {
 241   maybe_unwind_expanded_macro_loc (context, diagnostic,
 242                                    diagnostic_location (diagnostic));
 243 }
 244
 245 /* Default tree printer.   Handles declarations only.  */
 246 static bool
 247 default_tree_printer (pretty_printer *pp, text_info *text, const char *spec,
 248                       int precision, bool wide, bool set_locus, bool hash)
 249 {
 250   tree t;
 251
 252   /* FUTURE: %+x should set the locus.  */
 253   if (precision != 0 || wide || hash)
 254     return false;
 255
 256   switch (*spec)
 257     {
 258     case 'E':
 259       t = va_arg (*text->args_ptr, tree);
 260       if (TREE_CODE (t) == IDENTIFIER_NODE)
 261         {
 262           pp_identifier (pp, IDENTIFIER_POINTER (t));
 263           return true;
 264         }
 265       break;
 266
 267     case 'D':
 268       t = va_arg (*text->args_ptr, tree);
 269       if (VAR_P (t) && DECL_HAS_DEBUG_EXPR_P (t))
 270         t = DECL_DEBUG_EXPR (t);
 271       break;
 272
 273     case 'F':
 274     case 'T':
 275       t = va_arg (*text->args_ptr, tree);
 276       break;
 277
 278     case 'K':
 279       percent_K_format (text);
 280       return true;
 281
 282     default:
 283       return false;
 284     }
 285
 286   if (set_locus)
 287     text->set_location (0, DECL_SOURCE_LOCATION (t), true);
 288
 289   if (DECL_P (t))
 290     {
 291       const char *n = DECL_NAME (t)
 292         ? identifier_to_locale (lang_hooks.decl_printable_name (t, 2))
 293         : _("<anonymous>");
 294       pp_string (pp, n);
 295     }
 296   else
 297     dump_generic_node (pp, t, 0, TDF_DIAGNOSTIC, 0);
 298
 299   return true;
 300 }
 301
 302 /* Sets CONTEXT to use language independent diagnostics.  */
 303 void
 304 tree_diagnostics_defaults (diagnostic_context *context)
 305 {
 306   diagnostic_starter (context) = default_tree_diagnostic_starter;
 307   diagnostic_finalizer (context) = default_diagnostic_finalizer;
 308   diagnostic_format_decoder (context) = default_tree_printer;
 309 }