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