Collect names of multiple erroring parameters

Rather than stop immediately at the first failure, we can be a bit more
helpful by collecting up potentially multiple names at once.

We limit the list to 5 elements, just to limit the potential output in
the case of accidentally passing a list of hundreds or thousands of
elements into such a function.

Author: leonerd

pod/perldiag.pod

@@ -4167,6 +4167,9 @@ which is forbidden.  See L<perlvar/%{^HOOK}> and L<perlfunc/require EXPR>.
 non-optional named parameter, but the caller did not provide a value associated
 with that name.  The caller of the subroutine is presumably at fault.
 
+This message may report multiple parameter names, if more than one is found to
+be missing.  In that case it will use the word "parameters".
+
 The message attempts to include the name of the called subroutine.  If
 the subroutine has been aliased, the subroutine's original name will be
 shown, regardless of what name the caller used.
@@ -7535,6 +7538,9 @@ slurpy parameter, and the caller provided a name that did not
 match any declared named parameter.  The caller of the subroutine is
 presumably at fault.
 
+This message may report multiple parameter names, if more than one name was
+passed that does not match.  In that case it will use the word "parameters".
+
 The message attempts to include the name of the called subroutine.  If
 the subroutine has been aliased, the subroutine's original name will be
 shown, regardless of what name the caller used.

pp.c

@@ -7983,6 +7983,9 @@ PP(pp_multiparam)
             SvPADSTALE_on(PAD_SVl(named->padix));
         }
 
+        size_t n_errors = 0;
+        SV *error_names = NULL;
+
         while(argc) {
             SV **svp;
 
@@ -8060,22 +8063,48 @@ PP(pp_multiparam)
                 hv_store_ent(hv, name, newSVsv(val), 0);
             }
             else {
-                // TODO: Consider collecting up all the names of unrecognised
-                // in one string
-                croak_caller("Unrecognized named parameter '%" UTF8f "' to subroutine '%" SVf "'",
-                    UTF8fARG(true, namelen, namepv), S_find_runcv_name());
+                n_errors++;
+                if(!error_names)
+                    error_names = sv_2mortal(newSVpvs(""));
+                if(n_errors <= 5) {
+                    /* Only bother collecting up the first 5 */
+                    if(n_errors > 1)
+                        sv_catpvs(error_names, ", ");
+                    sv_catpvf(error_names, "'%" UTF8f "'", UTF8fARG(true, namelen, namepv));
+                }
             }
         }
 
+        if(n_errors) {
+            if(n_errors > 5)
+                sv_catpvs(error_names, ", ...");
+            /* diag_listed_as: Unrecognized named parameter '%s' to subroutine '%s' */
+            croak_caller("Unrecognized named parameter%s %" SVf " to subroutine '%" SVf "'",
+                n_errors > 1 ? "s" : "", SVfARG(error_names), SVfARG(S_find_runcv_name()));
+        }
+
         for(size_t namedix = 0; namedix < n_named; namedix++) {
             struct op_multiparam_named_aux *named = aux->named + namedix;
             if(!named->is_required || !SvPADSTALE(PAD_SVl(named->padix)))
                 continue;
 
-            // TODO: Consider collecting up all the names of missing
-            // parameters in one string
-            croak_caller("Missing required named parameter '%" UTF8f "' to subroutine '%" SVf "'",
-                    UTF8fARG(true, named->namelen, named->namepv), S_find_runcv_name());
+            n_errors++;
+            if(!error_names)
+                error_names = sv_2mortal(newSVpvs(""));
+            if(n_errors <= 5) {
+                /* Only bother collecting up the first 5 */
+                if(n_errors > 1)
+                    sv_catpvs(error_names, ", ");
+                sv_catpvf(error_names, "'%" UTF8f "'", UTF8fARG(true, named->namelen, named->namepv));
+            }
+        }
+
+        if(n_errors) {
+            if(n_errors > 5)
+                sv_catpvs(error_names, ", ...");
+            /* diag_listed_as: Missing required named parameter '%s' to subroutine '%s' */
+            croak_caller("Missing required named parameter%s %" SVf " to subroutine '%" SVf "'",
+                n_errors > 1 ? "s" : "", SVfARG(error_names), SVfARG(S_find_runcv_name()));
         }
     }
 

t/lib/croak/signatures

@@ -285,9 +285,30 @@ f(alpha => 123);             ## line 4
 EXPECT
 Missing required named parameter 'beta' to subroutine 'main::f' at - line 4.
 ########
+# NAME multiple missing required named
+no warnings 'experimental::signature_named_parameters';
+sub f (:$alpha, :$beta) { }  ## line 3
+f();                         ## line 4
+EXPECT
+Missing required named parameters 'alpha', 'beta' to subroutine 'main::f' at - line 4.
+########
 # NAME unrecognised named
 no warnings 'experimental::signature_named_parameters';
 sub f (:$alpha) { }             ## line 3
 f(alpha => 123, gamma => 456);  ## line 4
 EXPECT
 Unrecognized named parameter 'gamma' to subroutine 'main::f' at - line 4.
+########
+# NAME multiple unrecognised named
+no warnings 'experimental::signature_named_parameters';
+sub f (:$alpha) { }                           ## line 3
+f(alpha => 123, gamma => 456, delta => 789);  ## line 4
+EXPECT
+Unrecognized named parameters 'gamma', 'delta' to subroutine 'main::f' at - line 4.
+########
+# NAME multiple unrecognised named limiting
+no warnings 'experimental::signature_named_parameters';
+sub f (:$alpha) { }           ## line 3
+f(alpha => 123, 'a' .. 'z');  ## line 4
+EXPECT
+Unrecognized named parameters 'a', 'c', 'e', 'g', 'i', ... to subroutine 'main::f' at - line 4.