c++: fix source printing for "required from here" message

It seems the diagnostic machinery's source line printing respects
the pretty printer prefix, but this is undesirable for the call to
diagnostic_show_locus in print_instantiation_partial_context_line
(added in r14-4388-g1c45319b66edc9) since the prefix may have been
set when issuing an earlier, unrelated diagnostic and we just want
to print an unprefixed source line.

This patch naively fixes this by clearing the prefix before calling
diagnostic_show_locus.

Before this patch, for error60a.C below we'd print

gcc/testsuite/g++.dg/template/error60a.C: In function ‘void usage()’:
gcc/testsuite/g++.dg/template/error60a.C:24:3: error: ‘unrelated_error’ was not declared in this scope
   24 |   unrelated_error; // { dg-error "not declared" }
      |   ^~~~~~~~~~~~~~~
gcc/testsuite/g++.dg/template/error60a.C: In instantiation of ‘void test(Foo) [with Foo = int]’:
gcc/testsuite/g++.dg/template/error60a.C:25:13:   required from here
gcc/testsuite/g++.dg/template/error60a.C:24:3: error:    25 |   test<int> (42); // { dg-message " required from here" }
gcc/testsuite/g++.dg/template/error60a.C:24:3: error:       |   ~~~~~~~~~~^~~~
gcc/testsuite/g++.dg/template/error60a.C:19:24: error: invalid conversion from ‘int’ to ‘int*’ [-fpermissive]
   19 |   my_pointer<Foo> ptr (val); // { dg-error "invalid conversion from 'int' to 'int\\*'" }
      |                        ^~~
      |                        |
      |                        int
gcc/testsuite/g++.dg/template/error60a.C:9:20: note:   initializing argument 1 of ‘my_pointer<Foo>::my_pointer(Foo*) [with Foo = int]’
    9 |   my_pointer (Foo *ptr) // { dg-message " initializing argument 1" }
      |               ~~~~~^~~

and afterward we print

gcc/testsuite/g++.dg/template/error60a.C: In function ‘void usage()’:
gcc/testsuite/g++.dg/template/error60a.C:24:3: error: ‘unrelated_error’ was not declared in this scope
   24 |   unrelated_error; // { dg-error "not declared" }
      |   ^~~~~~~~~~~~~~~
gcc/testsuite/g++.dg/template/error60a.C: In instantiation of ‘void test(Foo) [with Foo = int]’:
gcc/testsuite/g++.dg/template/error60a.C:25:13:   required from here
   25 |   test<int> (42); // { dg-message " required from here" }
      |   ~~~~~~~~~~^~~~
gcc/testsuite/g++.dg/template/error60a.C:19:24: error: invalid conversion from ‘int’ to ‘int*’ [-fpermissive]
   19 |   my_pointer<Foo> ptr (val); // { dg-error "invalid conversion from 'int' to 'int\\*'" }
      |                        ^~~
      |                        |
      |                        int
gcc/testsuite/g++.dg/template/error60a.C:9:20: note:   initializing argument 1 of ‘my_pointer<Foo>::my_pointer(Foo*) [with Foo = int]’
    9 |   my_pointer (Foo *ptr) // { dg-message " initializing argument 1" }
      |               ~~~~~^~~

gcc/cp/ChangeLog:

	* error.cc (print_instantiation_partial_context_line): Clear the
	pretty printer prefix around the call to diagnostic_show_locus.

gcc/testsuite/ChangeLog:

	* g++.dg/concepts/diagnostic2.C: Expect source line printed
	for the "required from here" message.
	* g++.dg/template/error60a.C: New test.

diff --git a/gcc/cp/error.cc b/gcc/cp/error.cc
index 7074845154e38d0f80ecab7f4f565819fe72b4b8..37987ccb570d3c66ec8b2e54396812ada4d2ff7c 100644 (file)
--- a/gcc/cp/error.cc
+++ b/gcc/cp/error.cc
@@ -3793,7 +3793,9 @@ print_instantiation_partial_context_line (diagnostic_context *context,
                   : _("required from here\n"));
     }
   gcc_rich_location rich_loc (loc);
+  char *saved_prefix = pp_take_prefix (context->printer);
   diagnostic_show_locus (context, &rich_loc, DK_NOTE);
+  pp_set_prefix (context->printer, saved_prefix);
 }
 
 /* Same as print_instantiation_full_context but less verbose.  */

diff --git a/gcc/testsuite/g++.dg/concepts/diagnostic2.C b/gcc/testsuite/g++.dg/concepts/diagnostic2.C
index 6550ed6b3bd881980409ea9061b0e81e020e7f4c..d6f5872de2cf1740ec199683619ee5b055e63134 100644 (file)
--- a/gcc/testsuite/g++.dg/concepts/diagnostic2.C
+++ b/gcc/testsuite/g++.dg/concepts/diagnostic2.C
@@ -23,7 +23,11 @@ void
 baz()
 {
   bar<int>(); // { dg-error "no match" }
-/* { dg-begin-multiline-output "" }
+/* { dg-begin-multiline-output "for no match error" }
+   bar<int>();
+   ~~~~~~~~^~
+   { dg-end-multiline-output "" } */
+/* { dg-begin-multiline-output "for required from here message" }
    bar<int>();
    ~~~~~~~~^~
    { dg-end-multiline-output "" } */

diff --git a/gcc/testsuite/g++.dg/template/error60a.C b/gcc/testsuite/g++.dg/template/error60a.C
new file mode 100644 (file)
index 0000000..9d0f170
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/error60a.C
@@ -0,0 +1,46 @@
+// A version of error60.C that first issues an unrelated error
+// to cause the pretty printer prefix to get set, verifying we
+// still print the source line for the "required from here"
+// message correctly in that case.
+// { dg-options "-fdiagnostics-show-caret" }
+
+template <typename Foo>
+struct my_pointer
+{
+  my_pointer (Foo *ptr) // { dg-message " initializing argument 1" }
+  : m_ptr (ptr)
+  {}
+
+  Foo *m_ptr;
+};
+
+template <typename Foo>
+void test (Foo val)
+{
+  my_pointer<Foo> ptr (val); // { dg-error "invalid conversion from 'int' to 'int\\*'" }
+}
+
+void usage ()
+{
+  unrelated_error; // { dg-error "not declared" }
+  test<int> (42); // { dg-message " required from here" }
+  /* { dg-begin-multiline-output "" }
+   unrelated_error;
+   ^~~~~~~~~~~~~~~
+     { dg-end-multiline-output "" } */
+  /* { dg-begin-multiline-output "" }
+   test<int> (42);
+   ~~~~~~~~~~^~~~
+     { dg-end-multiline-output "" } */
+}
+
+  /* { dg-begin-multiline-output "" }
+   my_pointer (Foo *ptr)
+               ~~~~~^~~
+     { dg-end-multiline-output "" } */
+  /* { dg-begin-multiline-output "" }
+   my_pointer<Foo> ptr (val);
+                        ^~~
+                        |
+                        int
+     { dg-end-multiline-output "" } */