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) 1999-2014 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 "langhooks-def.h"
  32 #include "vec.h"
  33 #include "intl.h"
  34
  35 /* Prints out, if necessary, the name of the current function
  36    that caused an error.  Called from all error and warning functions.  */
  37 void
  38 diagnostic_report_current_function (diagnostic_context *context,
  39                                     diagnostic_info *diagnostic)
  40 {
  41   diagnostic_report_current_module (context, diagnostic->location);
  42   lang_hooks.print_error_function (context, LOCATION_FILE (input_location),
  43                                    diagnostic);
  44 }
  45
  46 static void
  47 default_tree_diagnostic_starter (diagnostic_context *context,
  48                                  diagnostic_info *diagnostic)
  49 {
  50   diagnostic_report_current_function (context, diagnostic);
  51   pp_set_prefix (context->printer, diagnostic_build_prefix (context,
  52                                                             diagnostic));
  53 }
  54
  55 /* This is a pair made of a location and the line map it originated
  56    from.  It's used in the maybe_unwind_expanded_macro_loc function
  57    below.  */
  58 typedef struct
  59 {
  60   const struct line_map *map;
  61   source_location where;
  62 } loc_map_pair;
  63
  64
  65 /* Unwind the different macro expansions that lead to the token which
  66    location is WHERE and emit diagnostics showing the resulting
  67    unwound macro expansion trace.  Let's look at an example to see how
  68    the trace looks like.  Suppose we have this piece of code,
  69    artificially annotated with the line numbers to increase
  70    legibility:
  71
  72     $ cat -n test.c
  73       1    #define OPERATE(OPRD1, OPRT, OPRD2) \
  74       2      OPRD1 OPRT OPRD2;
  75       3
  76       4    #define SHIFTL(A,B) \
  77       5      OPERATE (A,<<,B)
  78       6
  79       7    #define MULT(A) \
  80       8      SHIFTL (A,1)
  81       9
  82      10    void
  83      11    g ()
  84      12    {
  85      13      MULT (1.0);// 1.0 << 1; <-- so this is an error.
  86      14    }
  87
  88    Here is the diagnostic that we want the compiler to generate:
  89
  90     test.c: In function ‘g’:
  91     test.c:5:14: error: invalid operands to binary << (have ‘double’ and ‘int’)
  92     test.c:2:9: note: in definition of macro 'OPERATE'
  93     test.c:8:3: note: in expansion of macro 'SHIFTL'
  94     test.c:13:3: note: in expansion of macro 'MULT'
  95
  96    The part that goes from the third to the fifth line of this
  97    diagnostic (the lines containing the 'note:' string) is called the
  98    unwound macro expansion trace.  That's the part generated by this
  99    function.  */
 100
 101 static void
 102 maybe_unwind_expanded_macro_loc (diagnostic_context *context,
 103                                  const diagnostic_info *diagnostic,
 104                                  source_location where)
 105 {
 106   const struct line_map *map;
 107   vec<loc_map_pair> loc_vec = vNULL;
 108   unsigned ix;
 109   loc_map_pair loc, *iter;
 110
 111   map = linemap_lookup (line_table, where);
 112   if (!linemap_macro_expansion_map_p (map))
 113     return;
 114
 115   /* Let's unwind the macros that got expanded and led to the token
 116      which location is WHERE.  We are going to store these macros into
 117      LOC_VEC, so that we can later walk it at our convenience to
 118      display a somewhat meaningful trace of the macro expansion
 119      history to the user.  Note that the first macro of the trace
 120      (which is OPERATE in the example above) is going to be stored at
 121      the beginning of LOC_VEC.  */
 122
 123   do
 124     {
 125       loc.where = where;
 126       loc.map = map;
 127
 128       loc_vec.safe_push (loc);
 129
 130       /* WHERE is the location of a token inside the expansion of a
 131          macro.  MAP is the map holding the locations of that macro
 132          expansion.  Let's get the location of the token inside the
 133          context that triggered the expansion of this macro.
 134          This is basically how we go "down" in the trace of macro
 135          expansions that led to WHERE.  */
 136       where = linemap_unwind_toward_expansion (line_table, where, &map);
 137     } while (linemap_macro_expansion_map_p (map));
 138
 139   /* Now map is set to the map of the location in the source that
 140      first triggered the macro expansion.  This must be an ordinary map.  */
 141
 142   /* Walk LOC_VEC and print the macro expansion trace, unless the
 143      first macro which expansion triggered this trace was expanded
 144      inside a system header.  */
 145   int saved_location_line =
 146     expand_location_to_spelling_point (diagnostic->location).line;
 147
 148   if (!LINEMAP_SYSP (map))
 149     FOR_EACH_VEC_ELT (loc_vec, ix, iter)
 150       {
 151         /* Sometimes, in the unwound macro expansion trace, we want to
 152            print a part of the context that shows where, in the
 153            definition of the relevant macro, is the token (we are
 154            looking at) used.  That is the case in the introductory
 155            comment of this function, where we print:
 156
 157                test.c:2:9: note: in definition of macro 'OPERATE'.
 158
 159            We print that "macro definition context" because the
 160            diagnostic line (emitted by the call to
 161            pp_ouput_formatted_text in diagnostic_report_diagnostic):
 162
 163                test.c:5:14: error: invalid operands to binary << (have ‘double’ and ‘int’)
 164
 165            does not point into the definition of the macro where the
 166            token '<<' (that is an argument to the function-like macro
 167            OPERATE) is used.  So we must "display" the line of that
 168            macro definition context to the user somehow.
 169
 170            A contrario, when the first interesting diagnostic line
 171            points into the definition of the macro, we don't need to
 172            display any line for that macro definition in the trace
 173            anymore, otherwise it'd be redundant.  */
 174
 175         /* Okay, now here is what we want.  For each token resulting
 176            from macro expansion we want to show: 1/ where in the
 177            definition of the macro the token comes from; 2/ where the
 178            macro got expanded.  */
 179
 180         /* Resolve the location iter->where into the locus 1/ of the
 181            comment above.  */
 182         source_location resolved_def_loc =
 183           linemap_resolve_location (line_table, iter->where,
 184                                     LRK_MACRO_DEFINITION_LOCATION, NULL);
 185
 186         /* Don't print trace for locations that are reserved or from
 187            within a system header.  */
 188         const struct line_map *m = NULL;
 189         source_location l =
 190           linemap_resolve_location (line_table, resolved_def_loc,
 191                                     LRK_SPELLING_LOCATION,  &m);
 192         if (l < RESERVED_LOCATION_COUNT || LINEMAP_SYSP (m))
 193           continue;
 194
 195         /* We need to print the context of the macro definition only
 196            when the locus of the first displayed diagnostic (displayed
 197            before this trace) was inside the definition of the
 198            macro.  */
 199         int resolved_def_loc_line = SOURCE_LINE (m, l);
 200         if (ix == 0 && saved_location_line != resolved_def_loc_line)
 201           {
 202             diagnostic_append_note (context, resolved_def_loc,
 203                                     "in definition of macro %qs",
 204                                     linemap_map_get_macro_name (iter->map));
 205             /* At this step, as we've printed the context of the macro
 206                definition, we don't want to print the context of its
 207                expansion, otherwise, it'd be redundant.  */
 208             continue;
 209           }
 210
 211         /* Resolve the location of the expansion point of the macro
 212            which expansion gave the token represented by def_loc.
 213            This is the locus 2/ of the earlier comment.  */
 214         source_location resolved_exp_loc =
 215           linemap_resolve_location (line_table,
 216                                     MACRO_MAP_EXPANSION_POINT_LOCATION (iter->map),
 217                                     LRK_MACRO_DEFINITION_LOCATION, NULL);
 218
 219         diagnostic_append_note (context, resolved_exp_loc,
 220                                 "in expansion of macro %qs",
 221                                 linemap_map_get_macro_name (iter->map));
 222       }
 223
 224   loc_vec.release ();
 225 }
 226
 227 /*  This is a diagnostic finalizer implementation that is aware of
 228     virtual locations produced by libcpp.
 229
 230     It has to be called by the diagnostic finalizer of front ends that
 231     uses libcpp and wish to get diagnostics involving tokens resulting
 232     from macro expansion.
 233
 234     For a given location, if said location belongs to a token
 235     resulting from a macro expansion, this starter prints the context
 236     of the token.  E.g, for multiply nested macro expansion, it
 237     unwinds the nested macro expansions and prints them in a manner
 238     that is similar to what is done for function call stacks, or
 239     template instantiation contexts.  */
 240 void
 241 virt_loc_aware_diagnostic_finalizer (diagnostic_context *context,
 242                                      diagnostic_info *diagnostic)
 243 {
 244   maybe_unwind_expanded_macro_loc (context, diagnostic,
 245                                    diagnostic->location);
 246 }
 247
 248 /* Default tree printer.   Handles declarations only.  */
 249 static bool
 250 default_tree_printer (pretty_printer *pp, text_info *text, const char *spec,
 251                       int precision, bool wide, bool set_locus, bool hash)
 252 {
 253   tree t;
 254
 255   /* FUTURE: %+x should set the locus.  */
 256   if (precision != 0 || wide || hash)
 257     return false;
 258
 259   switch (*spec)
 260     {
 261     case 'E':
 262       t = va_arg (*text->args_ptr, tree);
 263       if (TREE_CODE (t) == IDENTIFIER_NODE)
 264         {
 265           pp_identifier (pp, IDENTIFIER_POINTER (t));
 266           return true;
 267         }
 268       break;
 269
 270     case 'D':
 271       t = va_arg (*text->args_ptr, tree);
 272       if (TREE_CODE (t) == VAR_DECL && DECL_HAS_DEBUG_EXPR_P (t))
 273         t = DECL_DEBUG_EXPR (t);
 274       break;
 275
 276     case 'F':
 277     case 'T':
 278       t = va_arg (*text->args_ptr, tree);
 279       break;
 280
 281     case 'K':
 282       percent_K_format (text);
 283       return true;
 284
 285     default:
 286       return false;
 287     }
 288
 289   if (set_locus && text->locus)
 290     *text->locus = DECL_SOURCE_LOCATION (t);
 291
 292   if (DECL_P (t))
 293     {
 294       const char *n = DECL_NAME (t)
 295         ? identifier_to_locale (lang_hooks.decl_printable_name (t, 2))
 296         : _("<anonymous>");
 297       pp_string (pp, n);
 298     }
 299   else
 300     dump_generic_node (pp, t, 0, TDF_DIAGNOSTIC, 0);
 301
 302   return true;
 303 }
 304
 305 /* Sets CONTEXT to use language independent diagnostics.  */
 306 void
 307 tree_diagnostics_defaults (diagnostic_context *context)
 308 {
 309   diagnostic_starter (context) = default_tree_diagnostic_starter;
 310   diagnostic_finalizer (context) = default_diagnostic_finalizer;
 311   diagnostic_format_decoder (context) = default_tree_printer;
 312 }