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) 1999-2015 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 "alias.h"
  26 #include "symtab.h"
  27 #include "options.h"
  28 #include "tree.h"
  29 #include "diagnostic.h"
  30 #include "tree-pretty-print.h"
  31 #include "tree-diagnostic.h"
  32 #include "dumpfile.h" /* TDF_DIAGNOSTIC */
  33 #include "langhooks.h"
  34 #include "langhooks-def.h"
  35 #include "intl.h"
  36
  37 /* Prints out, if necessary, the name of the current function
  38    that caused an error.  Called from all error and warning functions.  */
  39 void
  40 diagnostic_report_current_function (diagnostic_context *context,
  41                                     diagnostic_info *diagnostic)
  42 {
  43   diagnostic_report_current_module (context, diagnostic_location (diagnostic));
  44   lang_hooks.print_error_function (context, LOCATION_FILE (input_location),
  45                                    diagnostic);
  46 }
  47
  48 static void
  49 default_tree_diagnostic_starter (diagnostic_context *context,
  50                                  diagnostic_info *diagnostic)
  51 {
  52   diagnostic_report_current_function (context, diagnostic);
  53   pp_set_prefix (context->printer, diagnostic_build_prefix (context,
  54                                                             diagnostic));
  55 }
  56
  57 /* This is a pair made of a location and the line map it originated
  58    from.  It's used in the maybe_unwind_expanded_macro_loc function
  59    below.  */
  60 typedef struct
  61 {
  62   const line_map_macro *map;
  63   source_location where;
  64 } loc_map_pair;
  65
  66
  67 /* Unwind the different macro expansions that lead to the token which
  68    location is WHERE and emit diagnostics showing the resulting
  69    unwound macro expansion trace.  Let's look at an example to see how
  70    the trace looks like.  Suppose we have this piece of code,
  71    artificially annotated with the line numbers to increase
  72    legibility:
  73
  74     $ cat -n test.c
  75       1    #define OPERATE(OPRD1, OPRT, OPRD2) \
  76       2      OPRD1 OPRT OPRD2;
  77       3
  78       4    #define SHIFTL(A,B) \
  79       5      OPERATE (A,<<,B)
  80       6
  81       7    #define MULT(A) \
  82       8      SHIFTL (A,1)
  83       9
  84      10    void
  85      11    g ()
  86      12    {
  87      13      MULT (1.0);// 1.0 << 1; <-- so this is an error.
  88      14    }
  89
  90    Here is the diagnostic that we want the compiler to generate:
  91
  92     test.c: In function ‘g’:
  93     test.c:5:14: error: invalid operands to binary << (have ‘double’ and ‘int’)
  94     test.c:2:9: note: in definition of macro 'OPERATE'
  95     test.c:8:3: note: in expansion of macro 'SHIFTL'
  96     test.c:13:3: note: in expansion of macro 'MULT'
  97
  98    The part that goes from the third to the fifth line of this
  99    diagnostic (the lines containing the 'note:' string) is called the
 100    unwound macro expansion trace.  That's the part generated by this
 101    function.  */
 102
 103 static void
 104 maybe_unwind_expanded_macro_loc (diagnostic_context *context,
 105                                  const diagnostic_info *diagnostic,
 106                                  source_location where)
 107 {
 108   const struct line_map *map;
 109   vec<loc_map_pair> loc_vec = vNULL;
 110   unsigned ix;
 111   loc_map_pair loc, *iter;
 112
 113   map = linemap_lookup (line_table, where);
 114   if (!linemap_macro_expansion_map_p (map))
 115     return;
 116
 117   /* Let's unwind the macros that got expanded and led to the token
 118      which location is WHERE.  We are going to store these macros into
 119      LOC_VEC, so that we can later walk it at our convenience to
 120      display a somewhat meaningful trace of the macro expansion
 121      history to the user.  Note that the first macro of the trace
 122      (which is OPERATE in the example above) is going to be stored at
 123      the beginning of LOC_VEC.  */
 124
 125   do
 126     {
 127       loc.where = where;
 128       loc.map = linemap_check_macro (map);
 129
 130       loc_vec.safe_push (loc);
 131
 132       /* WHERE is the location of a token inside the expansion of a
 133          macro.  MAP is the map holding the locations of that macro
 134          expansion.  Let's get the location of the token inside the
 135          context that triggered the expansion of this macro.
 136          This is basically how we go "down" in the trace of macro
 137          expansions that led to WHERE.  */
 138       where = linemap_unwind_toward_expansion (line_table, where, &map);
 139     } while (linemap_macro_expansion_map_p (map));
 140
 141   /* Now map is set to the map of the location in the source that
 142      first triggered the macro expansion.  This must be an ordinary map.  */
 143   const line_map_ordinary *ord_map = linemap_check_ordinary (map);
 144
 145   /* Walk LOC_VEC and print the macro expansion trace, unless the
 146      first macro which expansion triggered this trace was expanded
 147      inside a system header.  */
 148   int saved_location_line =
 149     expand_location_to_spelling_point (diagnostic_location (diagnostic)).line;
 150
 151   if (!LINEMAP_SYSP (ord_map))
 152     FOR_EACH_VEC_ELT (loc_vec, ix, iter)
 153       {
 154         /* Sometimes, in the unwound macro expansion trace, we want to
 155            print a part of the context that shows where, in the
 156            definition of the relevant macro, is the token (we are
 157            looking at) used.  That is the case in the introductory
 158            comment of this function, where we print:
 159
 160                test.c:2:9: note: in definition of macro 'OPERATE'.
 161
 162            We print that "macro definition context" because the
 163            diagnostic line (emitted by the call to
 164            pp_ouput_formatted_text in diagnostic_report_diagnostic):
 165
 166                test.c:5:14: error: invalid operands to binary << (have ‘double’ and ‘int’)
 167
 168            does not point into the definition of the macro where the
 169            token '<<' (that is an argument to the function-like macro
 170            OPERATE) is used.  So we must "display" the line of that
 171            macro definition context to the user somehow.
 172
 173            A contrario, when the first interesting diagnostic line
 174            points into the definition of the macro, we don't need to
 175            display any line for that macro definition in the trace
 176            anymore, otherwise it'd be redundant.  */
 177
 178         /* Okay, now here is what we want.  For each token resulting
 179            from macro expansion we want to show: 1/ where in the
 180            definition of the macro the token comes from; 2/ where the
 181            macro got expanded.  */
 182
 183         /* Resolve the location iter->where into the locus 1/ of the
 184            comment above.  */
 185         source_location resolved_def_loc =
 186           linemap_resolve_location (line_table, iter->where,
 187                                     LRK_MACRO_DEFINITION_LOCATION, NULL);
 188
 189         /* Don't print trace for locations that are reserved or from
 190            within a system header.  */
 191         const line_map_ordinary *m = NULL;
 192         source_location l =
 193           linemap_resolve_location (line_table, resolved_def_loc,
 194                                     LRK_SPELLING_LOCATION,  &m);
 195         if (l < RESERVED_LOCATION_COUNT || LINEMAP_SYSP (m))
 196           continue;
 197
 198         /* We need to print the context of the macro definition only
 199            when the locus of the first displayed diagnostic (displayed
 200            before this trace) was inside the definition of the
 201            macro.  */
 202         int resolved_def_loc_line = SOURCE_LINE (m, l);
 203         if (ix == 0 && saved_location_line != resolved_def_loc_line)
 204           {
 205             diagnostic_append_note (context, resolved_def_loc,
 206                                     "in definition of macro %qs",
 207                                     linemap_map_get_macro_name (iter->map));
 208             /* At this step, as we've printed the context of the macro
 209                definition, we don't want to print the context of its
 210                expansion, otherwise, it'd be redundant.  */
 211             continue;
 212           }
 213
 214         /* Resolve the location of the expansion point of the macro
 215            which expansion gave the token represented by def_loc.
 216            This is the locus 2/ of the earlier comment.  */
 217         source_location resolved_exp_loc =
 218           linemap_resolve_location (line_table,
 219                                     MACRO_MAP_EXPANSION_POINT_LOCATION (iter->map),
 220                                     LRK_MACRO_DEFINITION_LOCATION, NULL);
 221
 222         diagnostic_append_note (context, resolved_exp_loc,
 223                                 "in expansion of macro %qs",
 224                                 linemap_map_get_macro_name (iter->map));
 225       }
 226
 227   loc_vec.release ();
 228 }
 229
 230 /*  This is a diagnostic finalizer implementation that is aware of
 231     virtual locations produced by libcpp.
 232
 233     It has to be called by the diagnostic finalizer of front ends that
 234     uses libcpp and wish to get diagnostics involving tokens resulting
 235     from macro expansion.
 236
 237     For a given location, if said location belongs to a token
 238     resulting from a macro expansion, this starter prints the context
 239     of the token.  E.g, for multiply nested macro expansion, it
 240     unwinds the nested macro expansions and prints them in a manner
 241     that is similar to what is done for function call stacks, or
 242     template instantiation contexts.  */
 243 void
 244 virt_loc_aware_diagnostic_finalizer (diagnostic_context *context,
 245                                      diagnostic_info *diagnostic)
 246 {
 247   maybe_unwind_expanded_macro_loc (context, diagnostic,
 248                                    diagnostic_location (diagnostic));
 249 }
 250
 251 /* Default tree printer.   Handles declarations only.  */
 252 static bool
 253 default_tree_printer (pretty_printer *pp, text_info *text, const char *spec,
 254                       int precision, bool wide, bool set_locus, bool hash)
 255 {
 256   tree t;
 257
 258   /* FUTURE: %+x should set the locus.  */
 259   if (precision != 0 || wide || hash)
 260     return false;
 261
 262   switch (*spec)
 263     {
 264     case 'E':
 265       t = va_arg (*text->args_ptr, tree);
 266       if (TREE_CODE (t) == IDENTIFIER_NODE)
 267         {
 268           pp_identifier (pp, IDENTIFIER_POINTER (t));
 269           return true;
 270         }
 271       break;
 272
 273     case 'D':
 274       t = va_arg (*text->args_ptr, tree);
 275       if (TREE_CODE (t) == VAR_DECL && DECL_HAS_DEBUG_EXPR_P (t))
 276         t = DECL_DEBUG_EXPR (t);
 277       break;
 278
 279     case 'F':
 280     case 'T':
 281       t = va_arg (*text->args_ptr, tree);
 282       break;
 283
 284     case 'K':
 285       percent_K_format (text);
 286       return true;
 287
 288     default:
 289       return false;
 290     }
 291
 292   if (set_locus)
 293     text->set_location (0, DECL_SOURCE_LOCATION (t));
 294
 295   if (DECL_P (t))
 296     {
 297       const char *n = DECL_NAME (t)
 298         ? identifier_to_locale (lang_hooks.decl_printable_name (t, 2))
 299         : _("<anonymous>");
 300       pp_string (pp, n);
 301     }
 302   else
 303     dump_generic_node (pp, t, 0, TDF_DIAGNOSTIC, 0);
 304
 305   return true;
 306 }
 307
 308 /* Sets CONTEXT to use language independent diagnostics.  */
 309 void
 310 tree_diagnostics_defaults (diagnostic_context *context)
 311 {
 312   diagnostic_starter (context) = default_tree_diagnostic_starter;
 313   diagnostic_finalizer (context) = default_diagnostic_finalizer;
 314   diagnostic_format_decoder (context) = default_tree_printer;
 315 }