[gcc r12-5455] c++: improved return expression location

[gcc r12-5455] c++: improved return expression location

[Jason Merrill]

https://gcc.gnu.org/g:5440c88e61f5c624eb87e19801eef6eedf27e8ab

commit r12-5455-g5440c88e61f5c624eb87e19801eef6eedf27e8ab
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Nov 19 17:01:10 2021 -0500

    c++: improved return expression location
    
    Stripping the location wrapper from retval meant we didn't have the
    necessary location information for any conversion diagnostics.  We only need
    the stripping for the named return value optimization, let's use the
    unstripped expression for everything else.
    
    gcc/cp/ChangeLog:
    
            * typeck.c (check_return_expr): Only strip location wrapper during
            NRV handling.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/cpp0x/pr65327.C: Adjust location.
            * g++.dg/cpp23/constexpr-nonlit4.C: Likewise.
            * g++.dg/cpp23/constexpr-nonlit5.C: Likewise.
            * g++.dg/cpp2a/constexpr-init1.C: Likewise.

Diff:
---
 gcc/cp/typeck.c                                | 11 ++++++-----
 gcc/testsuite/g++.dg/cpp0x/pr65327.C           |  4 ++--
 gcc/testsuite/g++.dg/cpp23/constexpr-nonlit4.C |  8 ++++----
 gcc/testsuite/g++.dg/cpp23/constexpr-nonlit5.C |  8 ++++----
 gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C   |  4 ++--
 5 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 58919aaf13e..63a0eaef2da 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -10545,19 +10545,20 @@ check_return_expr (tree retval, bool *no_warning)
      this restriction, anyway.  (jason 2000-11-19)
 
      See finish_function and finalize_nrv for the rest of this optimization.  */
+  tree bare_retval = NULL_TREE;
   if (retval)
     {
       retval = maybe_undo_parenthesized_ref (retval);
-      STRIP_ANY_LOCATION_WRAPPER (retval);
+      bare_retval = tree_strip_any_location_wrapper (retval);
     }
 
-  bool named_return_value_okay_p = can_do_nrvo_p (retval, functype);
+  bool named_return_value_okay_p = can_do_nrvo_p (bare_retval, functype);
   if (fn_returns_value_p && flag_elide_constructors)
     {
       if (named_return_value_okay_p
           && (current_function_return_value == NULL_TREE
-              || current_function_return_value == retval))
-	current_function_return_value = retval;
+	      || current_function_return_value == bare_retval))
+	current_function_return_value = bare_retval;
       else
 	current_function_return_value = error_mark_node;
     }
@@ -10571,7 +10572,7 @@ check_return_expr (tree retval, bool *no_warning)
     maybe_warn_pessimizing_move (retval, functype);
 
   /* Do any required conversions.  */
-  if (retval == result || DECL_CONSTRUCTOR_P (current_function_decl))
+  if (bare_retval == result || DECL_CONSTRUCTOR_P (current_function_decl))
     /* No conversions are required.  */
     ;
   else
diff --git a/gcc/testsuite/g++.dg/cpp0x/pr65327.C b/gcc/testsuite/g++.dg/cpp0x/pr65327.C
index 6e888ebff2c..e8149953ffd 100644
--- a/gcc/testsuite/g++.dg/cpp0x/pr65327.C
+++ b/gcc/testsuite/g++.dg/cpp0x/pr65327.C
@@ -14,5 +14,5 @@ foo ()
 constexpr volatile int // { dg-warning "deprecated" "" { target c++2a } }
 bar ()
 {
-  return i;
-} // { dg-error "lvalue-to-rvalue conversion of a volatile lvalue" }
+  return i;  // { dg-error "lvalue-to-rvalue conversion of a volatile lvalue" }
+}
diff --git a/gcc/testsuite/g++.dg/cpp23/constexpr-nonlit4.C b/gcc/testsuite/g++.dg/cpp23/constexpr-nonlit4.C
index e4ed2e36c30..bdc97a9bc79 100644
--- a/gcc/testsuite/g++.dg/cpp23/constexpr-nonlit4.C
+++ b/gcc/testsuite/g++.dg/cpp23/constexpr-nonlit4.C
@@ -34,7 +34,7 @@ baz (int x)
     {
       static const int v = qux ();	// { dg-message "'v' was not initialized with a constant expression" }
     case 12:
-      return v;
+      return v;	// { dg-error "the value of 'v' is not usable in a constant expression" }
     }
   return 0;
 }
@@ -46,12 +46,12 @@ corge (int x)
     {
       const thread_local int v = qux ();	// { dg-message "'v' was not initialized with a constant expression" }
     case 12:
-      return v;
+      return v; // { dg-error "the value of 'v' is not usable in a constant expression" }
     }
   return 0;
 }
 
 constexpr int a = foo (12);
 constexpr int b = bar (12);
-constexpr int c = baz (12);		// { dg-error "the value of 'v' is not usable in a constant expression" }
-constexpr int d = corge (12);		// { dg-error "the value of 'v' is not usable in a constant expression" }
+constexpr int c = baz (12);
+constexpr int d = corge (12);
diff --git a/gcc/testsuite/g++.dg/cpp23/constexpr-nonlit5.C b/gcc/testsuite/g++.dg/cpp23/constexpr-nonlit5.C
index 838f282c1f9..86d5dba77a3 100644
--- a/gcc/testsuite/g++.dg/cpp23/constexpr-nonlit5.C
+++ b/gcc/testsuite/g++.dg/cpp23/constexpr-nonlit5.C
@@ -34,7 +34,7 @@ baz (int x)
     {
       static int v = 6;	// { dg-message "int v' is not const" }
     case 12:
-      return v;
+      return v;	// { dg-error "the value of 'v' is not usable in a constant expression" }
     }
   return 0;
 }
@@ -46,12 +46,12 @@ corge (int x)
     {
       thread_local int v = 6;	// { dg-message "int v' is not const" }
     case 12:
-      return v;
+      return v;	// { dg-error "the value of 'v' is not usable in a constant expression" }
     }
   return 0;
 }
 
 constexpr int a = foo (12);
 constexpr int b = bar (12);
-constexpr int c = baz (12);		// { dg-error "the value of 'v' is not usable in a constant expression" }
-constexpr int d = corge (12);		// { dg-error "the value of 'v' is not usable in a constant expression" }
+constexpr int c = baz (12);
+constexpr int d = corge (12);
diff --git a/gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C b/gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C
index 75984a2fdcb..e56ecfed48a 100644
--- a/gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C
+++ b/gcc/testsuite/g++.dg/cpp2a/constexpr-init1.C
@@ -73,11 +73,11 @@ fn7 (bool b)
   int a; // { dg-message ".int a. is not const" }
   if (b)
     a = 42;
-  return a;
+  return a;		       // { dg-error "the value of .a. is not usable" }
 }
 
 static_assert (fn7 (true) == 42);
-static_assert (fn7 (false) == 42); // { dg-error "non-constant condition|the value of .a. is not usable" }
+static_assert (fn7 (false) == 42); // { dg-error "non-constant condition" }
 // { dg-message "in .constexpr. expansion of" "" { target *-*-* } .-1 }
 
 constexpr int