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libcpp: fix ICE comparing macro locations without column info [PR96391] 

PR preprocessor/96391 describes an ICE in the C++ frontend on:

  #define CONST const
  #define VOID void
  typedef CONST VOID *PCVOID;

where the typedef line occurs after enough code has been compiled
that location_t values are beyond LINE_MAP_MAX_LOCATION_WITH_COLS,
and hence no column numbers are available.

The issue occurs in linemap_compare_locations when comparing the
locations of the "const" and "void" tokens.
Upon resolving the LRK_MACRO_EXPANSION_POINT, both have the same
location_t, the line of the "typedef" (with no column), and so
the l0 == l1 clause is triggered, but they are not from the
same macro expansion, leading first_map_in_common to return NULL
and triggering the "abort" condition.

This patch fixes the issue by checking when the two macro expansion
point location_t values are equal that the value
<= LINE_MAP_MAX_LOCATION_WITH_COLS and thus has column information,
fixing the issue.

gcc/testsuite/ChangeLog:
	PR preprocessor/96391
	* g++.dg/plugin/location-overflow-test-pr96391.c: New test.
	* g++.dg/plugin/plugin.exp (plugin_test_list): Add it,
	using the location_overflow_plugin.c from gcc.dg/plugin.

libcpp/ChangeLog:
	PR preprocessor/96391
	* line-map.c (linemap_compare_locations): Require that
	the location be <= LINE_MAP_MAX_LOCATION_WITH_COLS when
	treating locations as coming from the same macro expansion.
This commit is contained in:
David Malcolm 2021-02-10 14:33:10 -05:00
parent 0f39fb7b00
commit 1f5c80883e
3 changed files with 16 additions and 1 deletions
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12
gcc/testsuite/g++.dg/plugin/location-overflow-test-pr96391.c Normal file
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@ -0,0 +1,12 @@
/* { dg-options "-fplugin-arg-location_overflow_plugin-value=0x60000001" } */
/* We use location_overflow_plugin.c, which injects the case that location_t
values have exceeded LINE_MAP_MAX_LOCATION_WITH_COLS, and hence no column
numbers are available. */
/* Verify that we're in column-less mode. */
extern unknown_type test; /* { dg-error "-:'unknown_type' does not name a type" } */
#define CONST const
#define VOID void
typedef CONST VOID *PCVOID;

2
gcc/testsuite/g++.dg/plugin/plugin.exp
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@ -72,6 +72,8 @@ set plugin_test_list [list \
../../gcc.dg/plugin/diagnostic-test-string-literals-2.c \
../../gcc.dg/plugin/diagnostic-test-string-literals-3.c \
../../gcc.dg/plugin/diagnostic-test-string-literals-4.c } \
{ ../../gcc.dg/plugin/location_overflow_plugin.c \
location-overflow-test-pr96391.c } \
{ show_template_tree_color_plugin.c \
show-template-tree-color.C \
show-template-tree-color-labels.C \

3
libcpp/line-map.c
View File

@ -1417,7 +1417,8 @@ linemap_compare_locations (line_maps *set,
if (l0 == l1
&& pre_virtual_p
&& post_virtual_p)
&& post_virtual_p
&& l0 <= LINE_MAP_MAX_LOCATION_WITH_COLS)
{
/* So pre and post represent two tokens that are present in a
same macro expansion. Let's see if the token for pre was