[PATCH v6 3/3] gdb: extend the [[N]]::foo syntax for files

[Guinevere Larsen <guinevere@redhat.com>]

This commit implements the missing support for [[N]]::'file.c'::var
syntax that was skipped on the previous commit.

This is done by adding a new value to the global parser_state, so that
the classify_name function can restrict its search for file names to the
specified linker namespace.  It had to be done this way because if the
logic was contained on the newly added "block: block COLONCOLON
FILENAME" rule, we would not have the name to rerun the search. Because
of that, the new rule only exists to make sure this is only used in the
intended syntax.  This commit also adds a link to the solib_ops relevant
to the expression being parsed, as a way to identify if linker
namespaces are supported; this could be achieved by guarding the search
functions instead, but I think that this is more reliable.

The new rule uses "block" rather than a linker namespace specific token,
because if we allowed that token to also reduce into block, the new rule
would never be triggered as the simple reduction would be preferred. If
we didn't allow the linker namespace to reduce into block, the rest of
the syntaxes for [[N]]::foo would be more involved, so the option in
this commit seemed like the simplest solution.

The rule "block: block COLONCOLON name" also had to be updated because,
if a user tried to search for a file not present in the linker
namespace, GDB would miscategorize it to 'name' instead of 'filename',
and if no function of the same name was found, the error would only say
"No function \"foo\" (...)" which could confuse a user. The new error
says "Nothing named \"foo\" (...)" instead since it is impossible for us
to disambiguate between filename or function name, and both would be
valid in this code path.

The parser_state changes were not used for the previous commit because
the lookup_symbol calls would lead to an even more intrusive change for
no real gain, since the search would be rerun any way. There is an
argument to be made that the results could be different if only
namespace had a type and another had a variable, but a situation where
that significantly changes the result is quite unlikely, I think.
---
 gdb/c-exp.y                               | 18 +++++++++++--
 gdb/linespec.c                            |  4 +--
 gdb/parse.c                               |  3 ++-
 gdb/parser-defs.h                         | 32 +++++++++++++++++++++--
 gdb/rust-parse.c                          |  3 ++-
 gdb/symtab.c                              | 26 +++++++++++++-----
 gdb/symtab.h                              |  7 ++++-
 gdb/testsuite/gdb.base/dlmopen-ns-ids.exp | 12 +++++++++
 8 files changed, 90 insertions(+), 15 deletions(-)

diff --git a/gdb/c-exp.y b/gdb/c-exp.y
index cb70bf3c863..f59aca327ed 100644
--- a/gdb/c-exp.y
+++ b/gdb/c-exp.y
@@ -1071,6 +1071,7 @@ block	:	BLOCKNAME
 			{
 			    $$.search_namespace = true;
 			    $$.namespace_val = $2.val;
+			    pstate->set_linker_namespace ($2.val);
 			}
 	;
 
@@ -1087,12 +1088,24 @@ block	:	block COLONCOLON name
 						 SEARCH_FUNCTION_DOMAIN,
 						 nullptr);
 
-			  if (tem.symbol == nullptr)
+			  if (tem.symbol == nullptr && !$$.search_namespace)
 			    error (_("No function \"%s\" in specified context."),
 				   copy.c_str ());
+			  else if (tem.symbol == nullptr && $$.search_namespace)
+			    /* COPY can be a function or a file.  There is no way
+			       to identify which the user intended, so emit a
+			       generic warning instead.  */
+			    error (_("Nothing named \"%s\" in specified context."),
+				   copy.c_str ());
 			  $$.b_val = tem.symbol->value_block ();
 			  $$.search_namespace = false;
 			}
+	|	block COLONCOLON FILENAME
+			{
+			    if (!$1.search_namespace)
+				error (_("Filename must be the first part of the expression"));
+			    $$ = $3;
+			}
 	;
 
 variable:	name_not_typename ENTRY
@@ -3173,7 +3186,8 @@ classify_name (struct parser_state *par_state, const struct block *block,
 	  || is_quoted_name)
 	{
 	  /* See if it's a file name. */
-	  if (auto symtab = lookup_symtab (current_program_space, copy.c_str ());
+	  if (auto symtab = lookup_symtab (current_program_space, copy.c_str (),
+					   par_state->get_linker_namespace ());
 	      symtab != nullptr)
 	    {
 	      yylval.bval.b_val
diff --git a/gdb/linespec.c b/gdb/linespec.c
index 08f7fdd0daa..ec90ad4826a 100644
--- a/gdb/linespec.c
+++ b/gdb/linespec.c
@@ -3633,11 +3633,11 @@ collect_symtabs_from_filename (const char *file,
 	  if (pspace->executing_startup)
 	    continue;
 
-	  iterate_over_symtabs (pspace, file, collector);
+	  iterate_over_symtabs (pspace, file, -1, collector);
 	}
     }
   else
-    iterate_over_symtabs (search_pspace, file, collector);
+    iterate_over_symtabs (search_pspace, file, -1, collector);
 
   /* It is tempting to use the unordered_dense 'extract' method here,
      and remove the separate vector -- but it's unclear if ordering
diff --git a/gdb/parse.c b/gdb/parse.c
index d76768f41d7..7358c369d52 100644
--- a/gdb/parse.c
+++ b/gdb/parse.c
@@ -420,7 +420,8 @@ parse_exp_in_context (const char **stringptr, CORE_ADDR pc,
 
   parser_state ps (lang, get_current_arch (), expression_context_block,
 		   expression_context_pc, flags, *stringptr,
-		   completer != nullptr, tracker);
+		   completer != nullptr, tracker,
+		   current_program_space->solib_ops ());
 
   scoped_restore_current_language lang_saver (lang->la_language);
 
diff --git a/gdb/parser-defs.h b/gdb/parser-defs.h
index ff4ab6a09de..c0be1083f66 100644
--- a/gdb/parser-defs.h
+++ b/gdb/parser-defs.h
@@ -26,6 +26,7 @@
 #include "expression.h"
 #include "symtab.h"
 #include "expop.h"
+#include "solib.h"
 
 struct block;
 struct language_defn;
@@ -147,7 +148,8 @@ struct parser_state : public expr_builder
 		parser_flags flags,
 		const char *input,
 		bool completion,
-		innermost_block_tracker *tracker)
+		innermost_block_tracker *tracker,
+		const solib_ops *ops)
     : expr_builder (lang, gdbarch),
       expression_context_block (context_block),
       expression_context_pc (context_pc),
@@ -157,7 +159,8 @@ struct parser_state : public expr_builder
       comma_terminates ((flags & PARSER_COMMA_TERMINATES) != 0),
       parse_completion (completion),
       void_context_p ((flags & PARSER_VOID_CONTEXT) != 0),
-      debug ((flags & PARSER_DEBUG) != 0)
+      debug ((flags & PARSER_DEBUG) != 0),
+      m_solib_ops (ops)
   {
   }
 
@@ -263,6 +266,21 @@ struct parser_state : public expr_builder
     push (expr::make_operation<T> (std::move (lhs), std::move (rhs)));
   }
 
+  void set_linker_namespace (LONGEST ns_id)
+  {
+    if (m_solib_ops == nullptr)
+      error (_("Linker namespaces require an active inferior"));
+    if (m_solib_ops->supports_namespaces ())
+      linker_namespace = ns_id;
+    else
+      error (_("Linker namespaces are not supported"));
+  }
+
+  LONGEST get_linker_namespace ()
+  {
+    return linker_namespace;
+  }
+
   /* Function called from the various parsers' yyerror functions to throw
      an error.  The error will include a message identifying the location
      of the error within the current expression.  */
@@ -323,6 +341,16 @@ struct parser_state : public expr_builder
 
   /* Stack of operations.  */
   std::vector<expr::operation_up> m_operations;
+
+  /* If the expression is being restricted to a specific namespace, this is
+     where that information is stored for the block lookup.  It should be
+     accessed through setter/getters to ensure that the linker namespace is
+     only set when the gdbarch supports it.  */
+  LONGEST linker_namespace = -1;
+
+  /* Used to figure out if an inferior is capable of handling linker
+     namespaces at all.  */
+  const solib_ops *m_solib_ops;
 };
 
 /* A string token, either a char-string or bit-string.  Char-strings are
diff --git a/gdb/rust-parse.c b/gdb/rust-parse.c
index b740d5a7b16..27f03b23e6a 100644
--- a/gdb/rust-parse.c
+++ b/gdb/rust-parse.c
@@ -2315,7 +2315,8 @@ rust_lex_tests (void)
 {
   /* Set up dummy "parser", so that rust_type works.  */
   parser_state ps (language_def (language_rust), current_inferior ()->arch (),
-		   nullptr, 0, 0, nullptr, 0, nullptr);
+		   nullptr, 0, 0, nullptr, 0, nullptr,
+		   current_program_space->solib_ops ());
   rust_parser parser (&ps);
 
   rust_lex_test_one (&parser, "", 0);
diff --git a/gdb/symtab.c b/gdb/symtab.c
index d237a5cc5d2..bbaf94e51d0 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -618,6 +618,7 @@ compare_filenames_for_search (const char *filename, const char *search_name)
 
 void
 iterate_over_symtabs (program_space *pspace, const char *name,
+		      LONGEST linker_ns,
 		      gdb::function_view<bool (symtab *)> callback)
 {
   gdb::unique_xmalloc_ptr<char> real_path;
@@ -630,20 +631,33 @@ iterate_over_symtabs (program_space *pspace, const char *name,
       gdb_assert (IS_ABSOLUTE_PATH (real_path.get ()));
     }
 
-  for (objfile &objfile : pspace->objfiles ())
-    if (objfile.map_symtabs_matching_filename (name, real_path.get (),
-					       callback))
+  std::vector<objfile *> objfiles_to_search;
+  if (linker_ns >= 0)
+    {
+      gdb_assert (pspace->solib_ops ()->supports_namespaces ());
+      objfiles_to_search
+	= get_objfiles_in_linker_namespace (linker_ns, pspace);
+    }
+  else
+    {
+      for (objfile &objf : pspace->objfiles ())
+	objfiles_to_search.push_back (&objf);
+    }
+
+  for (objfile *objfile : objfiles_to_search)
+    if (objfile->map_symtabs_matching_filename (name, real_path.get (),
+						callback))
       return;
 }
 
 /* See symtab.h.  */
 
 symtab *
-lookup_symtab (program_space *pspace, const char *name)
+lookup_symtab (program_space *pspace, const char *name, LONGEST linker_ns)
 {
   struct symtab *result = NULL;
 
-  iterate_over_symtabs (pspace, name, [&] (symtab *symtab)
+  iterate_over_symtabs (pspace, name, linker_ns, [&] (symtab *symtab)
     {
       result = symtab;
       return true;
@@ -6158,7 +6172,7 @@ collect_file_symbol_completion_matches (completion_tracker &tracker,
 
   /* Go through symtabs for SRCFILE and check the externs and statics
      for symbols which match.  */
-  iterate_over_symtabs (current_program_space, srcfile, [&] (symtab *s)
+  iterate_over_symtabs (current_program_space, srcfile, -1, [&] (symtab *s)
     {
       add_symtab_completions (s->compunit (),
 			      tracker, mode, lookup_name,
diff --git a/gdb/symtab.h b/gdb/symtab.h
index fe2304acb4f..bda6e82da02 100644
--- a/gdb/symtab.h
+++ b/gdb/symtab.h
@@ -2079,7 +2079,8 @@ const char *multiple_symbols_select_mode (void);
 
 /* Lookup a symbol table in PSPACE by source file name.  */
 
-extern symtab *lookup_symtab (program_space *pspace, const char *name);
+extern symtab *lookup_symtab (program_space *pspace, const char *name,
+			      LONGEST linker_ns = -1);
 
 /* An object of this type is passed as the 'is_a_field_of_this'
    argument to lookup_symbol and lookup_symbol_in_language.  */
@@ -2805,10 +2806,14 @@ bool compare_glob_filenames_for_search (const char *filename,
    psymtabs.  *If* there is no '/' in the name, a match after a '/' in the
    symtab filename will also work.
 
+   If LINKER_NS is 0 or greater, only the objfiles in the provided linker
+   namespace will be iterated over.
+
    Call CALLBACK with each symtab that is found.  If CALLBACK returns
    true, the search stops.  */
 
 void iterate_over_symtabs (program_space *pspace, const char *name,
+			   LONGEST linker_ns,
 			   gdb::function_view<bool (symtab *)> callback);
 
 std::vector<const linetable_entry *> find_linetable_entries_for_symtab_line
diff --git a/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp b/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp
index fec7adb5317..a1e18fc39d3 100644
--- a/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp
+++ b/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp
@@ -325,9 +325,15 @@ proc_with_prefix test_print_namespace_symbol {} {
     clean_restart
     gdb_load $::binfile
 
+    set ns0 [ns_id_for_command 0]
     set ns1 [ns_id_for_command 1]
     set ns2 [ns_id_for_command 2]
 
+    # Test printing variables before starting the inferior
+    gdb_test "print ${ns1}::gdb_dlmopen_glob" \
+	"Linker namespaces require an active inferior" \
+	"Before starting inferior"
+
     if { ![runto_main] } {
 	return
     }
@@ -365,6 +371,12 @@ proc_with_prefix test_print_namespace_symbol {} {
     # returning a random one, we just say we didn't find one.
     gdb_test "print gdb_dlmopen_glob" \
 	"No symbol .gdb_dlmopen_glob. in the current linker namespace."
+
+    # Minimal testing for finding files in namespaces.
+    gdb_test "print ${ns1}::'${::srcfile_lib}'::gdb_dlmopen_glob" \
+	".* = 2"
+    gdb_test "print ${ns0}::'${::srcfile_lib}'::gdb_dlmopen_glob" \
+	"Nothing named .${::srcfile_lib}. in specified context."
 }
 
 test_info_shared
-- 
2.51.0