Hi!
While std::source_location::current () is static consteval source_location
current() noexcept; in the standard, it also says with LWG3396:
"Any call to current that appears as a default member initializer
([class.mem]), or as a subexpression thereof, should correspond to the
location of the constructor definition or aggregate initialization that uses
the default member initializer. Any call to current that appears as a
default argument ([dcl.fct.default]), or as a subexpression thereof, should
correspond to the location of the invocation of the function that uses the
default argument ([expr.call])."
so it must work as compiler magic rather than normal immediate functions,
in particular we need to defer its evaluation when parsing default arguments
or nsdmis.
The following patch implements that.
Bootstrapped/regtested on x86_64-linux and i686-linux.
Jon, does it fix all the library testcases you and JeanHeyd had?
2020-12-01 Jakub Jelinek <ja...@redhat.com>
LWG3396 Clarify point of reference for source_location::current()
PR c++/80780
PR c++/93093
* cp-tree.h (source_location_current_p): Declare.
* tree.c (source_location_current_p): New function.
(bot_manip): Resolve deferred calls to immediate function
std::source_location::current ().
* call.c (build_over_call): Don't evaluate calls to immediate
function std::source_location::current () in default arguments
or when parsing nsdmi.
* g++.dg/cpp2a/srcloc15.C: New test.
* g++.dg/cpp2a/srcloc16.C: New test.
--- gcc/cp/cp-tree.h.jj 2020-11-26 16:22:24.252407018 +0100
+++ gcc/cp/cp-tree.h 2020-11-30 19:45:36.784286305 +0100
@@ -7413,6 +7413,7 @@ extern tree bind_template_template_parm
extern tree array_type_nelts_total (tree);
extern tree array_type_nelts_top (tree);
extern bool array_of_unknown_bound_p (const_tree);
+extern bool source_location_current_p (tree);
extern tree break_out_target_exprs (tree, bool = false);
extern tree build_ctor_subob_ref (tree, tree, tree);
extern tree replace_placeholders (tree, tree, bool * = NULL);
--- gcc/cp/tree.c.jj 2020-11-26 16:22:24.264406884 +0100
+++ gcc/cp/tree.c 2020-11-30 19:53:58.034686074 +0100
@@ -2968,6 +2968,37 @@ array_type_nelts_total (tree type)
return sz;
}
+/* Return true if FNDECL is std::source_location::current () method. */
+
+bool
+source_location_current_p (tree fndecl)
+{
+ gcc_checking_assert (TREE_CODE (fndecl) == FUNCTION_DECL
+ && DECL_IMMEDIATE_FUNCTION_P (fndecl));
+ if (DECL_NAME (fndecl) == NULL_TREE
+ || TREE_CODE (TREE_TYPE (fndecl)) != FUNCTION_TYPE
+ || TREE_CODE (TREE_TYPE (TREE_TYPE (fndecl))) != RECORD_TYPE
+ || DECL_CONTEXT (fndecl) != TREE_TYPE (TREE_TYPE (fndecl)))
+ return false;
+
+ if (strcmp (IDENTIFIER_POINTER (DECL_NAME (fndecl)), "current") != 0)
+ return false;
+
+ tree source_location = DECL_CONTEXT (fndecl);
+ if (TYPE_NAME (source_location) == NULL_TREE
+ || TREE_CODE (TYPE_NAME (source_location)) != TYPE_DECL
+ || DECL_NAME (TYPE_NAME (source_location)) == NULL_TREE
+ || strcmp (IDENTIFIER_POINTER (DECL_NAME (TYPE_NAME (source_location))),
+ "source_location") != 0)
+ return false;
+
+ tree decl
+ = lookup_qualified_name (std_node,
+ DECL_NAME (TYPE_NAME (source_location)),
+ LOOK_want::TYPE, tf_none);
+ return TYPE_NAME (source_location) == decl;
+}
+
struct bot_data
{
splay_tree target_remap;
@@ -3064,6 +3095,38 @@ bot_manip (tree* tp, int* walk_subtrees,
set_flags_from_callee (*tp);
if (data.clear_location && EXPR_HAS_LOCATION (*tp))
SET_EXPR_LOCATION (*tp, input_location);
+ if (TREE_CODE (*tp) == CALL_EXPR
+ && !processing_template_decl
+ && (current_function_decl == NULL_TREE
+ || !DECL_IMMEDIATE_FUNCTION_P (current_function_decl)))
+ if (tree fndecl = cp_get_callee_fndecl_nofold (*tp))
+ if (DECL_IMMEDIATE_FUNCTION_P (fndecl)
+ && source_location_current_p (fndecl))
+ {
+ bool ok = call_expr_nargs (*tp) == 0;
+ if (call_expr_nargs (*tp) == 1
+ && TREE_CODE (CALL_EXPR_ARG (*tp, 0)) == CALL_EXPR)
+ if (tree fndecl2
+ = cp_get_callee_fndecl_nofold (CALL_EXPR_ARG (*tp, 0)))
+ if (fndecl_built_in_p (fndecl2, CP_BUILT_IN_SOURCE_LOCATION,
+ BUILT_IN_FRONTEND))
+ ok = true;
+ if (!ok)
+ {
+ error_at (EXPR_LOCATION (*tp),
+ "%qD called with arguments", fndecl);
+ *tp = build_constructor (TREE_TYPE (TREE_TYPE (fndecl)),
+ NULL);
+ }
+ else
+ {
+ vec<tree, va_gc> *args = NULL;
+ push_deferring_access_checks (dk_no_check);
+ *tp = build_new_function_call (fndecl, &args,
+ tf_warning_or_error);
+ pop_deferring_access_checks ();
+ }
+ }
return t;
}
--- gcc/cp/call.c.jj 2020-11-18 09:40:09.000000000 +0100
+++ gcc/cp/call.c 2020-11-30 19:47:03.951312431 +0100
@@ -8613,7 +8613,9 @@ build_over_call (struct z_candidate *can
&& (current_function_decl == NULL_TREE
|| !DECL_IMMEDIATE_FUNCTION_P (current_function_decl))
&& (current_binding_level->kind != sk_function_parms
- || !current_binding_level->immediate_fn_ctx_p))
+ || (!current_binding_level->immediate_fn_ctx_p
+ && !source_location_current_p (fn)))
+ && (!parsing_nsdmi () || !source_location_current_p (fn)))
{
tree obj_arg = NULL_TREE, exprimm = expr;
if (DECL_CONSTRUCTOR_P (fn))
@@ -9257,7 +9259,9 @@ build_over_call (struct z_candidate *can
&& (current_function_decl == NULL_TREE
|| !DECL_IMMEDIATE_FUNCTION_P (current_function_decl))
&& (current_binding_level->kind != sk_function_parms
- || !current_binding_level->immediate_fn_ctx_p))
+ || (!current_binding_level->immediate_fn_ctx_p
+ && !source_location_current_p (fndecl)))
+ && (!parsing_nsdmi () || !source_location_current_p (fndecl)))
{
tree obj_arg = NULL_TREE;
if (DECL_CONSTRUCTOR_P (fndecl))
--- gcc/testsuite/g++.dg/cpp2a/srcloc15.C.jj 2020-11-30 17:57:41.506279816
+0100
+++ gcc/testsuite/g++.dg/cpp2a/srcloc15.C 2020-11-30 17:57:21.169507324
+0100
@@ -0,0 +1,82 @@
+// { dg-do compile { target c++20 } }
+
+namespace std {
+ struct source_location {
+ struct __impl {
+ const char *_M_file_name;
+ const char *_M_function_name;
+ unsigned int _M_line, _M_column;
+ };
+ const __impl *__ptr;
+ constexpr source_location () : __ptr (nullptr) {}
+ static consteval source_location
+ current (const void *__p = __builtin_source_location ()) {
+ source_location __ret;
+ __ret.__ptr = static_cast <const __impl *> (__p);
+ return __ret;
+ }
+ constexpr const char *file_name () const {
+ return __ptr ? __ptr->_M_file_name : "";
+ }
+ constexpr const char *function_name () const {
+ return __ptr ? __ptr->_M_function_name : "";
+ }
+ constexpr unsigned line () const {
+ return __ptr ? __ptr->_M_line : 0;
+ }
+ constexpr unsigned column () const {
+ return __ptr ? __ptr->_M_column : 0;
+ }
+ };
+}
+
+using namespace std;
+
+constexpr source_location
+foo (const source_location x = source_location::current ())
+{
+ return x;
+}
+
+constexpr bool
+bar ()
+{
+ int line = __LINE__;
+ source_location a = foo ();
+ source_location b = source_location::current ();
+ source_location c = foo ();
+ // ^ column 28
+ // ^ column 49
+ const source_location *d[3] = { &a, &b, &c };
+ const char *file1 = __FILE__;
+ const char *function1 = __FUNCTION__;
+ for (int j = 0; j < 3; j++)
+ {
+ int i= 0;
+ const char *file2 = d[j]->file_name ();
+ const char *function2 = d[j]->function_name ();
+ for (i = 0; file1[i]; i++)
+ if (file1[i] != file2[i])
+ return false;
+ if (file2[i])
+ return false;
+ for (i = 0; function1[i]; i++)
+ if (function1[i] != function2[i])
+ return false;
+ if (function2[i])
+ return false;
+ if (d[j]->line () != line + j + 1)
+ return false;
+ if (d[j]->column () != (j == 1 ? 49 : 28))
+ return false;
+ }
+ return true;
+}
+
+static_assert (bar ());
+
+int
+main ()
+{
+ bar ();
+}
--- gcc/testsuite/g++.dg/cpp2a/srcloc16.C.jj 2020-11-30 20:15:25.416283572
+0100
+++ gcc/testsuite/g++.dg/cpp2a/srcloc16.C 2020-11-30 20:15:06.285497601
+0100
@@ -0,0 +1,96 @@
+// { dg-do compile { target c++20 } }
+
+namespace std {
+ struct source_location {
+ struct __impl {
+ const char *_M_file_name;
+ const char *_M_function_name;
+ unsigned int _M_line, _M_column;
+ };
+ const __impl *__ptr;
+ constexpr source_location () : __ptr (nullptr) {}
+ static consteval source_location
+ current (const void *__p = __builtin_source_location ()) {
+ source_location __ret;
+ __ret.__ptr = static_cast <const __impl *> (__p);
+ return __ret;
+ }
+ constexpr const char *file_name () const {
+ return __ptr ? __ptr->_M_file_name : "";
+ }
+ constexpr const char *function_name () const {
+ return __ptr ? __ptr->_M_function_name : "";
+ }
+ constexpr unsigned line () const {
+ return __ptr ? __ptr->_M_line : 0;
+ }
+ constexpr unsigned column () const {
+ return __ptr ? __ptr->_M_column : 0;
+ }
+ };
+}
+
+using namespace std;
+
+struct S
+{
+ source_location a = source_location::current ();
+ source_location b = source_location::current ();
+ source_location c = source_location ();
+ constexpr S () { c = source_location::current (); }
+};
+
+struct T
+{
+ int t;
+ source_location u = source_location::current ();
+ int v = __builtin_LINE ();
+};
+
+constexpr S s;
+constexpr T t = { 1 };
+
+constexpr bool
+cmp (const char *p, const char *q)
+{
+ for (; *p && *q; p++, q++)
+ if (*p != *q)
+ return true;
+ return *p || *q;
+}
+
+constexpr bool
+foo ()
+{
+ T u = { 2 };
+ source_location v = source_location::current ();
+ if (cmp (s.a.file_name (), s.c.file_name ())
+ || cmp (s.b.file_name (), s.c.file_name ())
+ || cmp (t.u.file_name (), s.c.file_name ())
+ || cmp (u.u.file_name (), s.c.file_name ())
+ || cmp (v.file_name (), s.c.file_name ())
+ || cmp (s.a.function_name (), s.c.function_name ())
+ || cmp (s.b.function_name (), s.c.function_name ())
+ || cmp (t.u.function_name (), "")
+ || cmp (u.u.function_name (), v.function_name ())
+ || s.a.line () != s.c.line ()
+ || s.b.line () != s.c.line ()
+ || t.u.line () != t.v
+ || u.u.line () + 1 != v.line ()
+ || s.a.column () != 18
+ || s.b.column () != 18
+ || s.c.column () != 50
+ || t.u.column () != 21
+ || u.u.column () != 13
+ || v.column () != 49)
+ return false;
+ return true;
+}
+
+static_assert (foo ());
+
+int
+main ()
+{
+ foo ();
+}
Jakub
