Make "list ambiguous" show symbol names too

Currently, with an ambiguous "list first,last", we get:

  (gdb) list bar,main
  Specified first line 'bar' is ambiguous:
  file: "src/gdb/testsuite/gdb.cp/overload.cc", line number: 97
  file: "src/gdb/testsuite/gdb.cp/overload.cc", line number: 98

This commit makes gdb's output above a bit clearer by printing the
symbol name as well:

  (gdb) list bar,main
  Specified first line 'bar' is ambiguous:
  file: "src/gdb/testsuite/gdb.cp/overload.cc", line number: 97, symbol: "bar(A)"
  file: "src/gdb/testsuite/gdb.cp/overload.cc", line number: 98, symbol: "bar(B)"

And while at it, makes gdb print the symbol name when actually listing
multiple locations too.  I.e., before (with "set listsize 2"):

  (gdb) list bar
  file: "src/gdb/testsuite/gdb.cp/overload.cc", line number: 97
  96
  97      int bar (A) { return 11; }
  file: "src/gdb/testsuite/gdb.cp/overload.cc", line number: 98
  97      int bar (A) { return 11; }
  98      int bar (B) { return 22; }

After:

  (gdb) list bar
  file: "src/gdb/testsuite/gdb.cp/overload.cc", line number: 97, symbol: "bar(A)"
  96
  97      int bar (A) { return 11; }
  file: "src/gdb/testsuite/gdb.cp/overload.cc", line number: 98, symbol: "bar(B)"
  97      int bar (A) { return 11; }
  98      int bar (B) { return 22; }

Currently, the result of decoding a linespec loses information about
the original symbol that was found.  All we end up with is an address.
This makes it difficult to find the original symbol again to get at
its print name.  Fix that by storing a pointer to the symbol in the
sal.  We already store the symtab and obj_section, so it feels like a
natural progression to me.  This avoids having to do any extra symbol
lookup too.

gdb/ChangeLog:
2017-09-20  Pedro Alves  <palves@redhat.com>

	* cli/cli-cmds.c (list_command): Use print_sal_location.
	(print_sal_location): New function.
	(ambiguous_line_spec): Use print_sal_location.
	* linespec.c (symbol_to_sal): Record the symbol in the sal.
	* symtab.c (find_function_start_sal): Likewise.
	* symtab.h (symtab_and_line::symbol): New field.

gdb/testsuite/ChangeLog:
2017-09-20  Pedro Alves  <palves@redhat.com>

	* gdb.base/list-ambiguous.exp (test_list_ambiguous_symbol): Expect
	symbol names in gdb's output.
	* gdb.cp/overload.exp ("list all overloads"): Likewise.

8 files changed, 45 insertions, 12 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 1e0ae7d..8db2f6e 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,14 @@
 2017-09-20  Pedro Alves  <palves@redhat.com>
 
+	* cli/cli-cmds.c (list_command): Use print_sal_location.
+	(print_sal_location): New function.
+	(ambiguous_line_spec): Use print_sal_location.
+	* linespec.c (symbol_to_sal): Record the symbol in the sal.
+	* symtab.c (find_function_start_sal): Likewise.
+	* symtab.h (symtab_and_line::symbol): New field.
+
+2017-09-20  Pedro Alves  <palves@redhat.com>
+
 	* linespec.c (minsym_found): Handle non-text minsyms.
 	(symbol_to_sal): Record a sal.pc for non-block, non-label symbols.
 
diff --git a/gdb/cli/cli-cmds.c b/gdb/cli/cli-cmds.c
index 883844e..260fd3f 100644
--- a/gdb/cli/cli-cmds.c
+++ b/gdb/cli/cli-cmds.c
@@ -90,6 +90,8 @@ static void list_command (char *, int);
 
 /* Prototypes for local utility functions */
 
+static void print_sal_location (const symtab_and_line &sal);
+
 static void ambiguous_line_spec (gdb::array_view<const symtab_and_line> sals,
 				 const char *format, ...)
   ATTRIBUTE_PRINTF (2, 3);
@@ -1094,11 +1096,7 @@ list_command (char *arg, int from_tty)
 	  if (first_line < 1)
 	    first_line = 1;
 	  if (sals.size () > 1)
-	    {
-	      printf_filtered (_("file: \"%s\", line number: %d\n"),
-			       symtab_to_filename_for_display (sal.symtab),
-			       sal.line);
-	    }
+	    print_sal_location (sal);
 	  print_source_lines (sal.symtab,
 			      first_line,
 			      first_line + get_lines_to_list (),
@@ -1516,6 +1514,23 @@ alias_command (char *args, int from_tty)
     }
 }
 
+/* Print the file / line number / symbol name of the location
+   specified by SAL.  */
+
+static void
+print_sal_location (const symtab_and_line &sal)
+{
+  scoped_restore_current_program_space restore_pspace;
+  set_current_program_space (sal.pspace);
+
+  const char *sym_name = NULL;
+  if (sal.symbol != NULL)
+    sym_name = SYMBOL_PRINT_NAME (sal.symbol);
+  printf_filtered (_("file: \"%s\", line number: %d, symbol: \"%s\"\n"),
+		   symtab_to_filename_for_display (sal.symtab),
+		   sal.line, sym_name != NULL ? sym_name : "???");
+}
+
 /* Print a list of files and line numbers which a user may choose from
    in order to list a function which was specified ambiguously (as
    with `list classname::overloadedfuncname', for example).  The SALS
@@ -1533,9 +1548,7 @@ ambiguous_line_spec (gdb::array_view<const symtab_and_line> sals,
   va_end (ap);
 
   for (const auto &sal : sals)
-    printf_filtered (_("file: \"%s\", line number: %d\n"),
-		     symtab_to_filename_for_display (sal.symtab),
-		     sal.line);
+    print_sal_location (sal);
 }
 
 /* Comparison function for filter_sals.  Returns a qsort-style
diff --git a/gdb/linespec.c b/gdb/linespec.c
index 35ef159..6e472e2 100644
--- a/gdb/linespec.c
+++ b/gdb/linespec.c
@@ -4623,6 +4623,7 @@ symbol_to_sal (struct symtab_and_line *result,
 	{
 	  *result = {};
 	  result->symtab = symbol_symtab (sym);
+	  result->symbol = sym;
 	  result->line = SYMBOL_LINE (sym);
 	  result->pc = SYMBOL_VALUE_ADDRESS (sym);
 	  result->pspace = SYMTAB_PSPACE (result->symtab);
@@ -4638,6 +4639,7 @@ symbol_to_sal (struct symtab_and_line *result,
 	  /* We know its line number.  */
 	  *result = {};
 	  result->symtab = symbol_symtab (sym);
+	  result->symbol = sym;
 	  result->line = SYMBOL_LINE (sym);
 	  result->pc = SYMBOL_VALUE_ADDRESS (sym);
 	  result->pspace = SYMTAB_PSPACE (result->symtab);
diff --git a/gdb/symtab.c b/gdb/symtab.c
index b504cd6..bf7ee64 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -3461,6 +3461,7 @@ find_function_start_sal (struct symbol *sym, int funfirstline)
   obj_section *section = SYMBOL_OBJ_SECTION (symbol_objfile (sym), sym);
   symtab_and_line sal
     = find_pc_sect_line (BLOCK_START (SYMBOL_BLOCK_VALUE (sym)), section, 0);
+  sal.symbol = sym;
 
   if (funfirstline && sal.symtab != NULL
       && (COMPUNIT_LOCATIONS_VALID (SYMTAB_COMPUNIT (sal.symtab))
@@ -3484,6 +3485,7 @@ find_function_start_sal (struct symbol *sym, int funfirstline)
       sal.pspace = current_program_space;
       sal.pc = BLOCK_START (SYMBOL_BLOCK_VALUE (sym));
       sal.section = section;
+      sal.symbol = sym;
     }
 
   if (funfirstline)
diff --git a/gdb/symtab.h b/gdb/symtab.h
index 1bf77c1..8b429a8 100644
--- a/gdb/symtab.h
+++ b/gdb/symtab.h
@@ -1421,6 +1421,7 @@ struct symtab_and_line
   struct program_space *pspace = NULL;
 
   struct symtab *symtab = NULL;
+  struct symbol *symbol = NULL;
   struct obj_section *section = NULL;
   /* Line number.  Line numbers start at 1 and proceed through symtab->nlines.
      0 is never a valid line number; it is used to indicate that line number
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 7ab92a2..721bd81 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,11 @@
 2017-09-20  Pedro Alves  <palves@redhat.com>
 
+	* gdb.base/list-ambiguous.exp (test_list_ambiguous_symbol): Expect
+	symbol names in gdb's output.
+	* gdb.cp/overload.exp ("list all overloads"): Likewise.
+
+2017-09-20  Pedro Alves  <palves@redhat.com>
+
 	* gdb.base/list-ambiguous.exp (test_list_ambiguous_function):
 	Rename to ...
 	(test_list_ambiguous_symbol): ... this and add a symbol name
diff --git a/gdb/testsuite/gdb.base/list-ambiguous.exp b/gdb/testsuite/gdb.base/list-ambiguous.exp
index dd473ca..ace3494 100644
--- a/gdb/testsuite/gdb.base/list-ambiguous.exp
+++ b/gdb/testsuite/gdb.base/list-ambiguous.exp
@@ -48,8 +48,8 @@ proc test_list_ambiguous_symbol {symbol_line symbol} {
     set lines1_re [line_range_pattern [expr $lineno1 - 5] [expr $lineno1 + 4]]
 
     set any "\[^\r\n\]*"
-    set h0_re "file: \"${any}list-ambiguous0.c\", line number: $lineno0"
-    set h1_re "file: \"${any}list-ambiguous1.c\", line number: $lineno1"
+    set h0_re "file: \"${any}list-ambiguous0.c\", line number: $lineno0, symbol: \"$symbol\""
+    set h1_re "file: \"${any}list-ambiguous1.c\", line number: $lineno1, symbol: \"$symbol\""
     gdb_test "list $symbol" "${h0_re}${lines0_re}\r\n${h1_re}${lines1_re}"
 
     gdb_test "list main,$symbol" \
diff --git a/gdb/testsuite/gdb.cp/overload.exp b/gdb/testsuite/gdb.cp/overload.exp
index 8cb9311..3bf2a6a 100644
--- a/gdb/testsuite/gdb.cp/overload.exp
+++ b/gdb/testsuite/gdb.cp/overload.exp
@@ -351,8 +351,8 @@ with_test_prefix "list all overloads" {
     set lines2 [line_range_pattern [expr $line_bar_B - 5] [expr $line_bar_B + 4]]
 
     set any "\[^\r\n\]*"
-    set h1_re "file: \"${any}overload.cc\", line number: $line_bar_A"
-    set h2_re "file: \"${any}overload.cc\", line number: $line_bar_B"
+    set h1_re "file: \"${any}overload.cc\", line number: $line_bar_A, symbol: \"bar\\(A\\)\""
+    set h2_re "file: \"${any}overload.cc\", line number: $line_bar_B, symbol: \"bar\\(B\\)\""
     gdb_test "list bar" "${h1_re}${lines1}\r\n${h2_re}${lines2}"
 }