[2/2] Fix handling of namespace-scope undeduced auto decls.

Message ID 20190823231833.30678-2-jason@redhat.com
State New
Headers show
Series
  • [C++,1/2] * parser.c (cp_parser_nested_name_specifier_opt): Avoid redundant error.
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Commit Message

Jason Merrill Aug. 23, 2019, 11:18 p.m.
* decl2.c (decl_dependent_p): New.
	(mark_used): Check it instead of just processing_template_decl.
---
 gcc/cp/decl2.c                              | 24 ++++++++++++++++++++-
 gcc/testsuite/g++.dg/cpp1z/constexpr-if30.C | 10 +++++++++
 gcc/cp/ChangeLog                            |  5 +++++
 3 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-if30.C

-- 
2.21.0

Comments

Jason Merrill Aug. 23, 2019, 11:23 p.m. | #1
On Fri, Aug 23, 2019 at 4:18 PM Jason Merrill <jason@redhat.com> wrote:

Apparently git send-email only spawns the editor once, so I need to
edit both messages before exiting...

This testcase comes from committee reflector discussion: 'fn' can't be
dependent because it is not in the scope of any template parameters.

Tested x86_64-pc-linux-gnu, applying to trunk.

>         * decl2.c (decl_dependent_p): New.

>         (mark_used): Check it instead of just processing_template_decl.

> ---

>  gcc/cp/decl2.c                              | 24 ++++++++++++++++++++-

>  gcc/testsuite/g++.dg/cpp1z/constexpr-if30.C | 10 +++++++++

>  gcc/cp/ChangeLog                            |  5 +++++

>  3 files changed, 38 insertions(+), 1 deletion(-)

>  create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-if30.C

>

> diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c

> index a32108f9d16..134f6d6e3df 100644

> --- a/gcc/cp/decl2.c

> +++ b/gcc/cp/decl2.c

> @@ -5407,6 +5407,25 @@ cp_warn_deprecated_use (tree decl, tsubst_flags_t complain)

>    return warned;

>  }

>

> +/* True if DECL or its enclosing scope have unbound template parameters.  */

> +

> +bool

> +decl_dependent_p (tree decl)

> +{

> +  if (DECL_FUNCTION_SCOPE_P (decl)

> +      || TREE_CODE (decl) == CONST_DECL

> +      || TREE_CODE (decl) == USING_DECL

> +      || TREE_CODE (decl) == FIELD_DECL)

> +    decl = CP_DECL_CONTEXT (decl);

> +  if (tree tinfo = get_template_info (decl))

> +    if (any_dependent_template_arguments_p (TI_ARGS (tinfo)))

> +      return true;

> +  if (LAMBDA_FUNCTION_P (decl)

> +      && dependent_type_p (DECL_CONTEXT (decl)))

> +    return true;

> +  return false;

> +}

> +

>  /* Mark DECL (either a _DECL or a BASELINK) as "used" in the program.

>     If DECL is a specialization or implicitly declared class member,

>     generate the actual definition.  Return false if something goes

> @@ -5433,6 +5452,9 @@ mark_used (tree decl, tsubst_flags_t complain)

>        decl = OVL_FIRST (decl);

>      }

>

> +  if (!DECL_P (decl))

> +    return true;

> +

>    /* Set TREE_USED for the benefit of -Wunused.  */

>    TREE_USED (decl) = 1;

>    /* And for structured bindings also the underlying decl.  */

> @@ -5480,7 +5502,7 @@ mark_used (tree decl, tsubst_flags_t complain)

>        || DECL_LANG_SPECIFIC (decl) == NULL

>        || DECL_THUNK_P (decl))

>      {

> -      if (!processing_template_decl

> +      if (!decl_dependent_p (decl)

>           && !require_deduced_type (decl, complain))

>         return false;

>        return true;

> diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-if30.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-if30.C

> new file mode 100644

> index 00000000000..1e3d15dca1c

> --- /dev/null

> +++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-if30.C

> @@ -0,0 +1,10 @@

> +// { dg-do compile { target c++17 } }

> +

> +auto fn = [](auto i) {

> +    if constexpr (sizeof(i) == 1)

> +        return fn(123);                // { dg-error "auto" }

> +};

> +

> +int main() {

> +    fn('!');

> +}

> diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog

> index d07c0de82dd..e6c83b5338e 100644

> --- a/gcc/cp/ChangeLog

> +++ b/gcc/cp/ChangeLog

> @@ -1,3 +1,8 @@

> +2019-08-22  Jason Merrill  <jason@redhat.com>

> +

> +       * decl2.c (decl_dependent_p): New.

> +       (mark_used): Check it instead of just processing_template_decl.

> +

>  2019-08-22  Jason Merrill  <jason@redhat.com>

>

>         * parser.c (cp_parser_nested_name_specifier_opt): Avoid redundant

> --

> 2.21.0

>

Patch

diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c
index a32108f9d16..134f6d6e3df 100644
--- a/gcc/cp/decl2.c
+++ b/gcc/cp/decl2.c
@@ -5407,6 +5407,25 @@  cp_warn_deprecated_use (tree decl, tsubst_flags_t complain)
   return warned;
 }
 
+/* True if DECL or its enclosing scope have unbound template parameters.  */
+
+bool
+decl_dependent_p (tree decl)
+{
+  if (DECL_FUNCTION_SCOPE_P (decl)
+      || TREE_CODE (decl) == CONST_DECL
+      || TREE_CODE (decl) == USING_DECL
+      || TREE_CODE (decl) == FIELD_DECL)
+    decl = CP_DECL_CONTEXT (decl);
+  if (tree tinfo = get_template_info (decl))
+    if (any_dependent_template_arguments_p (TI_ARGS (tinfo)))
+      return true;
+  if (LAMBDA_FUNCTION_P (decl)
+      && dependent_type_p (DECL_CONTEXT (decl)))
+    return true;
+  return false;
+}
+
 /* Mark DECL (either a _DECL or a BASELINK) as "used" in the program.
    If DECL is a specialization or implicitly declared class member,
    generate the actual definition.  Return false if something goes
@@ -5433,6 +5452,9 @@  mark_used (tree decl, tsubst_flags_t complain)
       decl = OVL_FIRST (decl);
     }
 
+  if (!DECL_P (decl))
+    return true;
+
   /* Set TREE_USED for the benefit of -Wunused.  */
   TREE_USED (decl) = 1;
   /* And for structured bindings also the underlying decl.  */
@@ -5480,7 +5502,7 @@  mark_used (tree decl, tsubst_flags_t complain)
       || DECL_LANG_SPECIFIC (decl) == NULL
       || DECL_THUNK_P (decl))
     {
-      if (!processing_template_decl
+      if (!decl_dependent_p (decl)
 	  && !require_deduced_type (decl, complain))
 	return false;
       return true;
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-if30.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-if30.C
new file mode 100644
index 00000000000..1e3d15dca1c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-if30.C
@@ -0,0 +1,10 @@ 
+// { dg-do compile { target c++17 } }
+
+auto fn = [](auto i) {
+    if constexpr (sizeof(i) == 1)
+        return fn(123);		// { dg-error "auto" }
+};
+
+int main() {
+    fn('!');
+}
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index d07c0de82dd..e6c83b5338e 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@ 
+2019-08-22  Jason Merrill  <jason@redhat.com>
+
+	* decl2.c (decl_dependent_p): New.
+	(mark_used): Check it instead of just processing_template_decl.
+
 2019-08-22  Jason Merrill  <jason@redhat.com>
 
 	* parser.c (cp_parser_nested_name_specifier_opt): Avoid redundant