[C++ PATCH] Reject constexpr functions with function-try-block (PR c++/89513)

[C++ PATCH] Reject constexpr functions with function-try-block (PR c++/89513)

[Jakub Jelinek]

Hi!

C++ before 2a says that constexpr constructors may not have function-try-block
body, for other constexpr functions it instead says that the function body
can be (=delete, =default or compound-statement), but that rules out
function-try-block as well.

For ctors we were diagnostic this in
build_constexpr_constructor_member_initializers, but with worse locus, so
this patch diagnoses it for both ctors and other constexpr functions in the
same place.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

Or would you prefer to have P1002R1 implemented and thus make this perhaps a
pedwarn before cxx2a, similarly for the error on try block in the body and
tweak build_constexpr_constructor_member_initializers?  I think constexpr
evaluation handles TRY_BLOCK already.

2019-02-27  Jakub Jelinek  <jakub@redhat.com>

	PR c++/89513
	* parser.c (cp_parser_ctor_initializer_opt_and_function_body):
	Diagnose constexpr ctor or function with function-try-block.
	Formatting fix.
	* constexpr.c (build_constexpr_constructor_member_initializers):
	Don't diagnose constexpr ctor with function-try-block here.

	* g++.dg/cpp0x/constexpr-89513.C: New test.

--- gcc/cp/parser.c.jj	2019-02-23 11:32:45.705614155 +0100
+++ gcc/cp/parser.c	2019-02-27 14:18:26.211248671 +0100
@@ -22589,11 +22589,22 @@ cp_parser_ctor_initializer_opt_and_funct
 						  bool in_function_try_block)
 {
   tree body, list;
-  const bool check_body_p =
-     DECL_CONSTRUCTOR_P (current_function_decl)
-     && DECL_DECLARED_CONSTEXPR_P (current_function_decl);
+  const bool check_body_p
+     = (DECL_CONSTRUCTOR_P (current_function_decl)
+	&& DECL_DECLARED_CONSTEXPR_P (current_function_decl));
   tree last = NULL;
 
+  if (in_function_try_block
+      && DECL_DECLARED_CONSTEXPR_P (current_function_decl))
+    {
+      if (DECL_CONSTRUCTOR_P (current_function_decl))
+	error ("body of %<constexpr%> constructor cannot be "
+	       "a function-try-block");
+      else
+	error ("body of %<constexpr%> function cannot be "
+	       "a function-try-block");
+    }
+
   /* Begin the function body.  */
   body = begin_function_body ();
   /* Parse the optional ctor-initializer.  */
--- gcc/cp/constexpr.c.jj	2019-02-26 15:37:06.475371073 +0100
+++ gcc/cp/constexpr.c	2019-02-27 14:17:34.434096156 +0100
@@ -627,11 +627,8 @@ build_constexpr_constructor_member_initi
 	}
     }
   else if (TREE_CODE (body) == TRY_BLOCK)
-    {
-      error ("body of %<constexpr%> constructor cannot be "
-	     "a function-try-block");
-      return error_mark_node;
-    }
+    /* This should have been diagnosed earlier.  */
+    return error_mark_node;
   else if (EXPR_P (body))
     ok = build_data_member_initialization (body, &vec);
   else
--- gcc/testsuite/g++.dg/cpp0x/constexpr-89513.C.jj	2019-02-27 14:28:50.280033938 +0100
+++ gcc/testsuite/g++.dg/cpp0x/constexpr-89513.C	2019-02-27 14:34:51.585120108 +0100
@@ -0,0 +1,48 @@
+// PR c++/89513
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+constexpr bool foo ()
+try {			// { dg-error "body of 'constexpr' function cannot be a function-try-block" }
+  return true;
+} catch (...) {
+  return false;
+}			// { dg-error "body of 'constexpr' function" "" { target c++11_only } }
+
+#if __cplusplus > 201103L
+constexpr bool bar ()
+try {			// { dg-error "body of 'constexpr' function cannot be a function-try-block" "" { target c++14 } }
+  try {			// { dg-error "'try' in 'constexpr' function" "" { target c++14 } }
+    return true;
+  } catch (int) {
+    return false;
+  }
+} catch (...) {
+  return false;
+}
+
+constexpr bool baz ()
+{
+  try { return true; } catch (...) { return false; }	// { dg-error "'try' in 'constexpr' function" "" { target c++14 } }
+}
+#endif
+
+struct S {
+  constexpr S () try : m (1)	// { dg-error "body of 'constexpr' constructor cannot be a function-try-block" }
+  {
+#if __cplusplus > 201103L
+    try {		// { dg-error "'try' in 'constexpr' function" "" { target c++14 } }
+    } catch (int) {
+    }
+#endif
+  } catch (...) {
+  }
+  int m;
+};
+
+struct T {
+  constexpr T ()
+  try {			// { dg-error "body of 'constexpr' constructor cannot be a function-try-block" }
+  } catch (...) {
+  }
+};

	Jakub

Re: [C++ PATCH] Reject constexpr functions with function-try-block (PR c++/89513)

[Jason Merrill]

On 2/27/19 5:37 PM, Jakub Jelinek wrote:
> Hi!
> 
> C++ before 2a says that constexpr constructors may not have function-try-block
> body, for other constexpr functions it instead says that the function body
> can be (=delete, =default or compound-statement), but that rules out
> function-try-block as well.
> 
> For ctors we were diagnostic this in
> build_constexpr_constructor_member_initializers, but with worse locus, so
> this patch diagnoses it for both ctors and other constexpr functions in the
> same place.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> 
> Or would you prefer to have P1002R1 implemented and thus make this perhaps a
> pedwarn before cxx2a, similarly for the error on try block in the body and
> tweak build_constexpr_constructor_member_initializers?  I think constexpr
> evaluation handles TRY_BLOCK already.

That sounds better, yes.

> 2019-02-27  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR c++/89513
> 	* parser.c (cp_parser_ctor_initializer_opt_and_function_body):
> 	Diagnose constexpr ctor or function with function-try-block.
> 	Formatting fix.
> 	* constexpr.c (build_constexpr_constructor_member_initializers):
> 	Don't diagnose constexpr ctor with function-try-block here.
> 
> 	* g++.dg/cpp0x/constexpr-89513.C: New test.
> 
> --- gcc/cp/parser.c.jj	2019-02-23 11:32:45.705614155 +0100
> +++ gcc/cp/parser.c	2019-02-27 14:18:26.211248671 +0100
> @@ -22589,11 +22589,22 @@ cp_parser_ctor_initializer_opt_and_funct
>   						  bool in_function_try_block)
>   {
>     tree body, list;
> -  const bool check_body_p =
> -     DECL_CONSTRUCTOR_P (current_function_decl)
> -     && DECL_DECLARED_CONSTEXPR_P (current_function_decl);
> +  const bool check_body_p
> +     = (DECL_CONSTRUCTOR_P (current_function_decl)
> +	&& DECL_DECLARED_CONSTEXPR_P (current_function_decl));
>     tree last = NULL;
>   
> +  if (in_function_try_block
> +      && DECL_DECLARED_CONSTEXPR_P (current_function_decl))
> +    {
> +      if (DECL_CONSTRUCTOR_P (current_function_decl))
> +	error ("body of %<constexpr%> constructor cannot be "
> +	       "a function-try-block");
> +      else
> +	error ("body of %<constexpr%> function cannot be "
> +	       "a function-try-block");
> +    }
> +
>     /* Begin the function body.  */
>     body = begin_function_body ();
>     /* Parse the optional ctor-initializer.  */
> --- gcc/cp/constexpr.c.jj	2019-02-26 15:37:06.475371073 +0100
> +++ gcc/cp/constexpr.c	2019-02-27 14:17:34.434096156 +0100
> @@ -627,11 +627,8 @@ build_constexpr_constructor_member_initi
>   	}
>       }
>     else if (TREE_CODE (body) == TRY_BLOCK)
> -    {
> -      error ("body of %<constexpr%> constructor cannot be "
> -	     "a function-try-block");
> -      return error_mark_node;
> -    }
> +    /* This should have been diagnosed earlier.  */
> +    return error_mark_node;
>     else if (EXPR_P (body))
>       ok = build_data_member_initialization (body, &vec);
>     else
> --- gcc/testsuite/g++.dg/cpp0x/constexpr-89513.C.jj	2019-02-27 14:28:50.280033938 +0100
> +++ gcc/testsuite/g++.dg/cpp0x/constexpr-89513.C	2019-02-27 14:34:51.585120108 +0100
> @@ -0,0 +1,48 @@
> +// PR c++/89513
> +// { dg-do compile { target c++11 } }
> +// { dg-options "" }
> +
> +constexpr bool foo ()
> +try {			// { dg-error "body of 'constexpr' function cannot be a function-try-block" }
> +  return true;
> +} catch (...) {
> +  return false;
> +}			// { dg-error "body of 'constexpr' function" "" { target c++11_only } }
> +
> +#if __cplusplus > 201103L
> +constexpr bool bar ()
> +try {			// { dg-error "body of 'constexpr' function cannot be a function-try-block" "" { target c++14 } }
> +  try {			// { dg-error "'try' in 'constexpr' function" "" { target c++14 } }
> +    return true;
> +  } catch (int) {
> +    return false;
> +  }
> +} catch (...) {
> +  return false;
> +}
> +
> +constexpr bool baz ()
> +{
> +  try { return true; } catch (...) { return false; }	// { dg-error "'try' in 'constexpr' function" "" { target c++14 } }
> +}
> +#endif
> +
> +struct S {
> +  constexpr S () try : m (1)	// { dg-error "body of 'constexpr' constructor cannot be a function-try-block" }
> +  {
> +#if __cplusplus > 201103L
> +    try {		// { dg-error "'try' in 'constexpr' function" "" { target c++14 } }
> +    } catch (int) {
> +    }
> +#endif
> +  } catch (...) {
> +  }
> +  int m;
> +};
> +
> +struct T {
> +  constexpr T ()
> +  try {			// { dg-error "body of 'constexpr' constructor cannot be a function-try-block" }
> +  } catch (...) {
> +  }
> +};
> 
> 	Jakub
> 

[C++ PATCH] Reject constexpr functions with function-try-block (PR c++/89513, take 2)

[Jakub Jelinek]

On Wed, Feb 27, 2019 at 06:48:13PM -0500, Jason Merrill wrote:
> > Or would you prefer to have P1002R1 implemented and thus make this perhaps a
> > pedwarn before cxx2a, similarly for the error on try block in the body and
> > tweak build_constexpr_constructor_member_initializers?  I think constexpr
> > evaluation handles TRY_BLOCK already.
> 
> That sounds better, yes.

Ok, here is an updated patch that does that.

Bootstrapped/regtested on x86_64-linux and i686-linux (98,11,14,17,2a in
both cases), ok for trunk?

2019-02-28  Jakub Jelinek  <jakub@redhat.com>

	Implement P1002R1, Try-catch blocks in constexpr functions
	PR c++/89513
	* parser.c (cp_parser_ctor_initializer_opt_and_function_body):
	Diagnose constexpr ctor or function with function-try-block with
	pedwarn for c++17 and earlier.  Formatting fix.
	(cp_parser_try_block): Use pedwarn instead of error and only for
	c++17 and earlier when try block appears in constexpr function.
	* constexpr.c (build_constexpr_constructor_member_initializers):
	Handle TRY_BLOCK here instead of erroring on it.

	* g++.dg/cpp2a/constexpr-try1.C: New test.
	* g++.dg/cpp2a/constexpr-try2.C: New test.
	* g++.dg/cpp2a/constexpr-try3.C: New test.
	* g++.dg/cpp2a/constexpr-try4.C: New test.
	* g++.dg/cpp2a/constexpr-try5.C: New test.
	* g++.dg/cpp0x/constexpr-ctor10.C: Don't expect error for C++2a.

--- gcc/cp/parser.c.jj	2019-02-28 08:14:58.240563115 +0100
+++ gcc/cp/parser.c	2019-02-28 09:37:21.498804731 +0100
@@ -22590,11 +22590,25 @@ cp_parser_ctor_initializer_opt_and_funct
 						  bool in_function_try_block)
 {
   tree body, list;
-  const bool check_body_p =
-     DECL_CONSTRUCTOR_P (current_function_decl)
-     && DECL_DECLARED_CONSTEXPR_P (current_function_decl);
+  const bool check_body_p
+     = (DECL_CONSTRUCTOR_P (current_function_decl)
+	&& DECL_DECLARED_CONSTEXPR_P (current_function_decl));
   tree last = NULL;
 
+  if (in_function_try_block
+      && DECL_DECLARED_CONSTEXPR_P (current_function_decl)
+      && cxx_dialect < cxx2a)
+    {
+      if (DECL_CONSTRUCTOR_P (current_function_decl))
+	pedwarn (input_location, 0,
+		 "function-try-block body of %<constexpr%> constructor only "
+		 "available with -std=c++2a or -std=gnu++2a");
+      else
+	pedwarn (input_location, 0,
+		 "function-try-block body of %<constexpr%> function only "
+		 "available with -std=c++2a or -std=gnu++2a");
+    }
+
   /* Begin the function body.  */
   body = begin_function_body ();
   /* Parse the optional ctor-initializer.  */
@@ -25329,8 +25343,11 @@ cp_parser_try_block (cp_parser* parser)
 
   cp_parser_require_keyword (parser, RID_TRY, RT_TRY);
   if (parser->in_function_body
-      && DECL_DECLARED_CONSTEXPR_P (current_function_decl))
-    error ("%<try%> in %<constexpr%> function");
+      && DECL_DECLARED_CONSTEXPR_P (current_function_decl)
+      && cxx_dialect < cxx2a)
+    pedwarn (input_location, 0,
+	     "%<try%> in %<constexpr%> function only "
+	     "available with -std=c++2a or -std=gnu++2a");
 
   try_block = begin_try_block ();
   cp_parser_compound_statement (parser, NULL, BCS_TRY_BLOCK, false);
--- gcc/cp/constexpr.c.jj	2019-02-27 15:49:26.946419095 +0100
+++ gcc/cp/constexpr.c	2019-02-28 10:07:48.219840527 +0100
@@ -601,6 +601,12 @@ build_constexpr_constructor_member_initi
 	gcc_unreachable ();
     }
  found:
+  if (TREE_CODE (body) == TRY_BLOCK)
+    {
+      body = TREE_OPERAND (body, 0);
+      if (TREE_CODE (body) == BIND_EXPR)
+	body = BIND_EXPR_BODY (body);
+    }
   if (TREE_CODE (body) == CLEANUP_POINT_EXPR)
     {
       body = TREE_OPERAND (body, 0);
@@ -626,12 +632,6 @@ build_constexpr_constructor_member_initi
 	    break;
 	}
     }
-  else if (TREE_CODE (body) == TRY_BLOCK)
-    {
-      error ("body of %<constexpr%> constructor cannot be "
-	     "a function-try-block");
-      return error_mark_node;
-    }
   else if (EXPR_P (body))
     ok = build_data_member_initialization (body, &vec);
   else
--- gcc/testsuite/g++.dg/cpp2a/constexpr-try1.C.jj	2019-02-28 09:38:13.651949049 +0100
+++ gcc/testsuite/g++.dg/cpp2a/constexpr-try1.C	2019-02-28 10:15:15.301509905 +0100
@@ -0,0 +1,44 @@
+// PR c++/89513
+// { dg-do compile { target c++11 } }
+
+constexpr bool foo ()
+try {			// { dg-error "function-try-block body of 'constexpr' function only available with" "" { target c++17_down } }
+  return true;
+} catch (...) {		// { dg-error "compound-statement in 'constexpr' function" "" { target c++11_only } }
+  return false;
+}			// { dg-error "body of 'constexpr' function" "" { target c++11_only } }
+
+constexpr bool bar ()
+try {			// { dg-error "function-try-block body of 'constexpr' function only available with" "" { target c++17_down } }
+  try {			// { dg-error "'try' in 'constexpr' function only available with" "" { target c++17_down } }
+    return true;	// { dg-error "compound-statement in 'constexpr' function" "" { target c++11_only } .-1 }
+  } catch (int) {	// { dg-error "compound-statement in 'constexpr' function" "" { target c++11_only } }
+    return false;
+  }
+} catch (...) {		// { dg-error "compound-statement in 'constexpr' function" "" { target c++11_only } }
+  return false;
+}			// { dg-error "not a return-statement" "" { target c++11_only } }
+
+constexpr bool baz ()
+{
+  try { return true; } catch (...) { return false; }	// { dg-error "'try' in 'constexpr' function only available with" "" { target c++17_down } }
+}			// { dg-error "not a return-statement" "" { target c++11_only } }
+			// { dg-error "compound-statement in 'constexpr' function" "" { target c++11_only } .-2 }
+
+struct S {
+  constexpr S () try : m (1)	// { dg-error "function-try-block body of 'constexpr' constructor only available with" "" { target c++17_down } }
+  {
+    try {		// { dg-error "'try' in 'constexpr' function only available with" "" { target c++17_down } }
+    } catch (int) {	// { dg-error "compound-statement in 'constexpr' function" "" { target c++11_only } }
+    }			// { dg-error "compound-statement in 'constexpr' function" "" { target c++11_only } .-2 }
+  } catch (...) {	// { dg-error "'constexpr' constructor does not have empty body" "" { target c++11_only } }
+  }
+  int m;
+};
+
+struct T {
+  constexpr T ()
+  try {			// { dg-error "function-try-block body of 'constexpr' constructor only available with" "" { target c++17_down } }
+  } catch (...) {	// { dg-error "compound-statement in 'constexpr' function" "" { target c++11_only } }
+  }
+};
--- gcc/testsuite/g++.dg/cpp2a/constexpr-try2.C.jj	2019-02-28 10:15:24.807354041 +0100
+++ gcc/testsuite/g++.dg/cpp2a/constexpr-try2.C	2019-02-28 10:17:13.508571718 +0100
@@ -0,0 +1,45 @@
+// PR c++/89513
+// { dg-do compile { target c++11 } }
+// { dg-options "-pedantic" }
+
+constexpr bool foo ()
+try {			// { dg-warning "function-try-block body of 'constexpr' function only available with" "" { target c++17_down } }
+  return true;
+} catch (...) {		// { dg-warning "compound-statement in 'constexpr' function" "" { target c++11_only } }
+  return false;
+}			// { dg-error "body of 'constexpr' function" "" { target c++11_only } }
+
+constexpr bool bar ()
+try {			// { dg-warning "function-try-block body of 'constexpr' function only available with" "" { target c++17_down } }
+  try {			// { dg-warning "'try' in 'constexpr' function only available with" "" { target c++17_down } }
+    return true;	// { dg-warning "compound-statement in 'constexpr' function" "" { target c++11_only } .-1 }
+  } catch (int) {	// { dg-warning "compound-statement in 'constexpr' function" "" { target c++11_only } }
+    return false;
+  }
+} catch (...) {		// { dg-warning "compound-statement in 'constexpr' function" "" { target c++11_only } }
+  return false;
+}			// { dg-error "not a return-statement" "" { target c++11_only } }
+
+constexpr bool baz ()
+{
+  try { return true; } catch (...) { return false; }	// { dg-warning "'try' in 'constexpr' function only available with" "" { target c++17_down } }
+}			// { dg-error "not a return-statement" "" { target c++11_only } }
+			// { dg-warning "compound-statement in 'constexpr' function" "" { target c++11_only } .-2 }
+
+struct S {
+  constexpr S () try : m (1)	// { dg-warning "function-try-block body of 'constexpr' constructor only available with" "" { target c++17_down } }
+  {
+    try {		// { dg-warning "'try' in 'constexpr' function only available with" "" { target c++17_down } }
+    } catch (int) {	// { dg-warning "compound-statement in 'constexpr' function" "" { target c++11_only } }
+    }			// { dg-warning "compound-statement in 'constexpr' function" "" { target c++11_only } .-2 }
+  } catch (...) {	// { dg-error "'constexpr' constructor does not have empty body" "" { target c++11_only } }
+  }
+  int m;
+};
+
+struct T {
+  constexpr T ()
+  try {			// { dg-warning "function-try-block body of 'constexpr' constructor only available with" "" { target c++17_down } }
+  } catch (...) {	// { dg-warning "compound-statement in 'constexpr' function" "" { target c++11_only } }
+  }
+};
--- gcc/testsuite/g++.dg/cpp2a/constexpr-try3.C.jj1	2019-02-28 10:49:41.436744795 +0100
+++ gcc/testsuite/g++.dg/cpp2a/constexpr-try3.C	2019-02-28 10:21:37.469243648 +0100
@@ -0,0 +1,44 @@
+// PR c++/89513
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+constexpr bool foo ()
+try {			// { dg-warning "function-try-block body of 'constexpr' function only available with" "" { target c++17_down } }
+  return true;
+} catch (...) {
+  return false;
+}			// { dg-error "body of 'constexpr' function" "" { target c++11_only } }
+
+constexpr bool bar ()
+try {			// { dg-warning "function-try-block body of 'constexpr' function only available with" "" { target c++17_down } }
+  try {			// { dg-warning "'try' in 'constexpr' function only available with" "" { target c++17_down } }
+    return true;
+  } catch (int) {
+    return false;
+  }
+} catch (...) {
+  return false;
+}			// { dg-error "not a return-statement" "" { target c++11_only } }
+
+constexpr bool baz ()
+{
+  try { return true; } catch (...) { return false; }	// { dg-warning "'try' in 'constexpr' function only available with" "" { target c++17_down } }
+}			// { dg-error "not a return-statement" "" { target c++11_only } }
+
+struct S {
+  constexpr S () try : m (1)	// { dg-warning "function-try-block body of 'constexpr' constructor only available with" "" { target c++17_down } }
+  {
+    try {		// { dg-warning "'try' in 'constexpr' function only available with" "" { target c++17_down } }
+    } catch (int) {
+    }
+  } catch (...) {	// { dg-error "'constexpr' constructor does not have empty body" "" { target c++11_only } }
+  }
+  int m;
+};
+
+struct T {
+  constexpr T ()
+  try {			// { dg-warning "function-try-block body of 'constexpr' constructor only available with" "" { target c++17_down } }
+  } catch (...) {
+  }
+};
--- gcc/testsuite/g++.dg/cpp2a/constexpr-try4.C.jj	2019-02-28 10:26:09.785798575 +0100
+++ gcc/testsuite/g++.dg/cpp2a/constexpr-try4.C	2019-02-28 10:33:06.632994747 +0100
@@ -0,0 +1,61 @@
+// PR c++/89513
+// { dg-do compile { target c++14 } }
+// { dg-options "" }
+
+constexpr int foo ()
+try {			// { dg-warning "function-try-block body of 'constexpr' function only available with" "" { target c++17_down } }
+  int a = 1;
+  for (int i = 0; i < 10; i++)
+    a += i;
+  return a;
+} catch (...) {
+  return -1;
+}
+
+constexpr int bar ()
+try {			// { dg-warning "function-try-block body of 'constexpr' function only available with" "" { target c++17_down } }
+  int a = 0;
+  for (int i = 0; i < 9; i++)
+    try {			// { dg-warning "'try' in 'constexpr' function only available with" "" { target c++17_down } }
+      a += i;
+    } catch (int) {
+      return -1;
+    }
+  return a;
+} catch (...) {
+  return -2;
+}
+
+constexpr bool baz ()
+{
+  try { return true; } catch (...) { return false; }	// { dg-warning "'try' in 'constexpr' function only available with" "" { target c++17_down } }
+}
+
+struct S {
+  constexpr S () try : m (1)	// { dg-warning "function-try-block body of 'constexpr' constructor only available with" "" { target c++17_down } }
+  {
+    try {		// { dg-warning "'try' in 'constexpr' function only available with" "" { target c++17_down } }
+      m += 2;
+    } catch (int) {
+      m = -1;
+    }
+  } catch (...) {
+    m = -2;
+  }
+  int m;
+  constexpr int get () const { return m; }
+};
+
+struct T {
+  constexpr T ()
+  try {			// { dg-warning "function-try-block body of 'constexpr' constructor only available with" "" { target c++17_down } }
+  } catch (...) {
+  }
+};
+
+static_assert (foo () == 46, "");
+static_assert (bar () == 36, "");
+static_assert (baz (), "");
+constexpr S s;
+static_assert (s.get () == 3, "");
+constexpr T t;
--- gcc/testsuite/g++.dg/cpp2a/constexpr-try5.C.jj	2019-02-28 10:33:53.783225162 +0100
+++ gcc/testsuite/g++.dg/cpp2a/constexpr-try5.C	2019-02-28 10:44:47.392549962 +0100
@@ -0,0 +1,40 @@
+// PR c++/89513
+// { dg-do compile { target c++14 } }
+// { dg-options "" }
+
+constexpr int foo ()
+try {			// { dg-warning "function-try-block body of 'constexpr' function only available with" "" { target c++17_down } }
+  int a;		// { dg-error "uninitialized variable 'a' in 'constexpr' function" }
+  static double b = 1.0;// { dg-error "'b' declared 'static' in 'constexpr' function" }
+  goto l;		// { dg-error "'goto' in 'constexpr' function" }
+  l:;
+  return 0;
+} catch (...) {
+  long int c;		// { dg-error "uninitialized variable 'c' in 'constexpr' function" }
+  static float d = 2.0f;// { dg-error "'d' declared 'static' in 'constexpr' function" }
+  goto l2;		// { dg-error "'goto' in 'constexpr' function" }
+  l2:;
+  return -1;
+}
+
+constexpr int bar ()
+{
+  int a;		// { dg-error "uninitialized variable 'a' in 'constexpr' function" }
+  static long double b = 3.0;// { dg-error "'b' declared 'static' in 'constexpr' function" }
+  goto l;		// { dg-error "'goto' in 'constexpr' function" }
+  l:;
+  try {			// { dg-warning "'try' in 'constexpr' function only available with" "" { target c++17_down } }
+    short c;		// { dg-error "uninitialized variable 'c' in 'constexpr' function" }
+    static float d;	// { dg-error "'d' declared 'static' in 'constexpr' function" }
+			// { dg-error "uninitialized variable 'd' in 'constexpr' function" "" { target *-*-* } .-1 }
+    goto l2;		// { dg-error "'goto' in 'constexpr' function" }
+    l2:;
+    return 0;
+  } catch (int) {
+    char e;		// { dg-error "uninitialized variable 'e' in 'constexpr' function" }
+    static int f = 5;	// { dg-error "'f' declared 'static' in 'constexpr' function" }
+    goto l3;		// { dg-error "'goto' in 'constexpr' function" }
+    l3:;
+    return 1;
+  }
+}
--- gcc/testsuite/g++.dg/cpp0x/constexpr-ctor10.C.jj	2014-03-10 10:50:13.252983951 +0100
+++ gcc/testsuite/g++.dg/cpp0x/constexpr-ctor10.C	2019-02-28 09:40:47.378426863 +0100
@@ -2,5 +2,5 @@
 // { dg-do compile { target c++11 } }
 
 struct foo {
-  constexpr foo() try { } catch(...) { };  // { dg-error "constexpr" }
+  constexpr foo() try { } catch(...) { };  // { dg-error "constexpr" "" { target c++17_down } }
 };


	Jakub

Re: [C++ PATCH] Reject constexpr functions with function-try-block (PR c++/89513, take 2)

[Jason Merrill]

On 2/28/19 6:03 PM, Jakub Jelinek wrote:
> On Wed, Feb 27, 2019 at 06:48:13PM -0500, Jason Merrill wrote:
>>> Or would you prefer to have P1002R1 implemented and thus make this perhaps a
>>> pedwarn before cxx2a, similarly for the error on try block in the body and
>>> tweak build_constexpr_constructor_member_initializers?  I think constexpr
>>> evaluation handles TRY_BLOCK already.
>>
>> That sounds better, yes.
> 
> Ok, here is an updated patch that does that.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux (98,11,14,17,2a in
> both cases), ok for trunk?
> 
> 2019-02-28  Jakub Jelinek  <jakub@redhat.com>
> 
> 	Implement P1002R1, Try-catch blocks in constexpr functions
> 	PR c++/89513
> 	* parser.c (cp_parser_ctor_initializer_opt_and_function_body):
> 	Diagnose constexpr ctor or function with function-try-block with
> 	pedwarn for c++17 and earlier.  Formatting fix.
> 	(cp_parser_try_block): Use pedwarn instead of error and only for
> 	c++17 and earlier when try block appears in constexpr function.
> 	* constexpr.c (build_constexpr_constructor_member_initializers):
> 	Handle TRY_BLOCK here instead of erroring on it.

OK.

Jason