[committed] libcpp: preserve ranges within macro expansions (PR c++/79300)

[committed] libcpp: preserve ranges within macro expansions (PR c++/79300)

[David Malcolm]

Comment #4 of PR c++/79300 noted a place in which we fail to underline
the full token of a macro name in maybe_unwind_expanded_macro_loc.

Root cause is that linemap_macro_loc_to_def_point drops range
information too early when following the macro expansions; fixed thusly.

Successfully bootstrapped&regrtested on x86_64-pc-linux-gnu.

Committed to trunk as r250058.

gcc/testsuite/ChangeLog:
	PR c++/79300
	* g++.dg/diagnostic/pr79300.C: New test case.

libcpp/ChangeLog:
	PR c++/79300
	* line-map.c (linemap_macro_loc_to_def_point): Preserve range
	information for macro expansions by delaying resolving ad-hoc
	locations until within the loop.
---
 gcc/testsuite/g++.dg/diagnostic/pr79300.C | 44 +++++++++++++++++++++++++++++++
 libcpp/line-map.c                         | 14 +++++-----
 2 files changed, 52 insertions(+), 6 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/diagnostic/pr79300.C

diff --git a/gcc/testsuite/g++.dg/diagnostic/pr79300.C b/gcc/testsuite/g++.dg/diagnostic/pr79300.C
new file mode 100644
index 0000000..6805e85
--- /dev/null
+++ b/gcc/testsuite/g++.dg/diagnostic/pr79300.C
@@ -0,0 +1,44 @@
+// { dg-options "-fdiagnostics-show-caret" }
+
+#define TEST_1_DEPTH_0 throw bad_alloc; // { dg-line define_TEST_1_DEPTH_0 }
+
+void test_1 ()
+{
+  TEST_1_DEPTH_0 // { dg-line use_TEST_1_DEPTH_0 }
+}
+
+// { dg-error "'bad_alloc' was not declared in this scope" "" { target *-*-* } define_TEST_1_DEPTH_0 }
+/* { dg-begin-multiline-output "" }
+ #define TEST_1_DEPTH_0 throw bad_alloc;
+                              ^~~~~~~~~
+   { dg-end-multiline-output "" } */
+// { dg-message "in expansion of macro 'TEST_1_DEPTH_0'" "" { target *-*-* } use_TEST_1_DEPTH_0 }
+/* { dg-begin-multiline-output "" }
+   TEST_1_DEPTH_0
+   ^~~~~~~~~~~~~~
+   { dg-end-multiline-output "" } */
+
+
+#define TEST_2_DEPTH_0 throw bad_alloc; // { dg-line define_TEST_2_DEPTH_0 }
+#define TEST_2_DEPTH_1 TEST_2_DEPTH_0 // { dg-line define_TEST_2_DEPTH_1 }
+
+void test_2 ()
+{
+  TEST_2_DEPTH_1 // { dg-line use_TEST_2_DEPTH_1 }
+}
+
+// { dg-error "'bad_alloc' was not declared in this scope" "" { target *-*-* } define_TEST_2_DEPTH_0 }
+/* { dg-begin-multiline-output "" }
+ #define TEST_2_DEPTH_0 throw bad_alloc;
+                              ^~~~~~~~~
+   { dg-end-multiline-output "" } */
+// { dg-message "in expansion of macro 'TEST_2_DEPTH_0'" "" { target *-*-* } define_TEST_2_DEPTH_1 }
+/* { dg-begin-multiline-output "" }
+ #define TEST_2_DEPTH_1 TEST_2_DEPTH_0
+                        ^~~~~~~~~~~~~~
+   { dg-end-multiline-output "" } */
+// { dg-message "in expansion of macro 'TEST_2_DEPTH_1'" "" { target *-*-* } use_TEST_2_DEPTH_1 }
+/* { dg-begin-multiline-output "" }
+   TEST_2_DEPTH_1
+   ^~~~~~~~~~~~~~
+   { dg-end-multiline-output "" } */
diff --git a/libcpp/line-map.c b/libcpp/line-map.c
index 1c1acc8..300cfd0 100644
--- a/libcpp/line-map.c
+++ b/libcpp/line-map.c
@@ -1439,21 +1439,23 @@ linemap_macro_loc_to_def_point (struct line_maps *set,
 {
   struct line_map *map;
 
-  if (IS_ADHOC_LOC (location))
-    location = set->location_adhoc_data_map.data[location
-						 & MAX_SOURCE_LOCATION].locus;
-
   linemap_assert (set && location >= RESERVED_LOCATION_COUNT);
 
   while (true)
     {
-      map = const_cast <line_map *> (linemap_lookup (set, location));
+      source_location caret_loc;
+      if (IS_ADHOC_LOC (location))
+	caret_loc = get_location_from_adhoc_loc (set, location);
+      else
+	caret_loc = location;
+
+      map = const_cast <line_map *> (linemap_lookup (set, caret_loc));
       if (!linemap_macro_expansion_map_p (map))
 	break;
 
       location =
 	linemap_macro_map_loc_to_def_point (linemap_check_macro (map),
-					    location);
+					    caret_loc);
     }
 
   if (original_map)
-- 
1.8.5.3