Reduce duplicated warnings for the change of Ruby 3 keyword arguments

By this change, the following code prints only one warning.

```
def foo(**opt); end
100.times { foo({kw:1}) }
```

A global variable `st_table *caller_to_callees` is a map from caller to
a set of callee methods.  It remembers that a warning is already printed
for each pair of caller and callee.

[Feature #16289]

1 files changed, 61 insertions, 10 deletions

diff --git a/vm_args.c b/vm_args.c
index 6729d54af7..c46b3cf2a4 100644
--- a/vm_args.c
+++ b/vm_args.c
@@ -585,9 +585,56 @@ ignore_keyword_hash_p(VALUE keyword_hash, const rb_iseq_t * const iseq) {
 
 VALUE rb_iseq_location(const rb_iseq_t *iseq);
 
+/* -- Remove In 3.0 -- */
+
+/* This is a map from caller PC to a set of callee methods.
+ * When a warning about keyword argument change is printed,
+ * it keeps the pair of callee and caller.
+ */
+static st_table *caller_to_callees = 0;
+
+static VALUE rb_warn_check(const rb_execution_context_t * const ec, const void *const callee)
+{
+    const rb_control_frame_t * const cfp = rb_vm_get_ruby_level_next_cfp(ec, ec->cfp);
+
+    if (!cfp) return 0;
+
+    const void *const caller = cfp->pc;
+
+    if (!caller_to_callees) {
+        caller_to_callees = st_init_numtable();
+    }
+
+    st_data_t val;
+    if (st_lookup(caller_to_callees, (st_data_t) caller, &val)) {
+        st_table *callees;
+
+        if (val & 1) {
+            val &= ~(st_data_t)1;
+            if (val == (st_data_t) callee) return 1; /* already warned */
+
+            callees = st_init_numtable();
+            st_insert(callees, val, 1);
+        }
+        else {
+            callees = (st_table *) val;
+            if (st_is_member(callees, (st_data_t) callee)) return 1; /* already warned */
+        }
+        st_insert(callees, (st_data_t) callee, 1);
+        st_insert(caller_to_callees, (st_data_t) caller, (st_data_t) callees);
+    }
+    else {
+        st_insert(caller_to_callees, (st_data_t) caller, ((st_data_t) callee) | 1);
+    }
+
+    return 0; /* not warned yet for the pair of caller and callee */
+}
+
 static inline void
-rb_warn_keyword_to_last_hash(struct rb_calling_info *calling, const struct rb_call_info *ci, const rb_iseq_t * const iseq)
+rb_warn_keyword_to_last_hash(rb_execution_context_t * const ec, struct rb_calling_info *calling, const struct rb_call_info *ci, const rb_iseq_t * const iseq)
 {
+    if (rb_warn_check(ec, iseq)) return;
+
     VALUE name, loc;
     if (calling->recv == Qundef) {
         rb_warn("The keyword argument is passed as the last hash parameter");
@@ -613,8 +660,10 @@ rb_warn_keyword_to_last_hash(struct rb_calling_info *calling, const struct rb_ca
 }
 
 static inline void
-rb_warn_split_last_hash_to_keyword(struct rb_calling_info *calling, const struct rb_call_info *ci, const rb_iseq_t * const iseq)
+rb_warn_split_last_hash_to_keyword(rb_execution_context_t * const ec, struct rb_calling_info *calling, const struct rb_call_info *ci, const rb_iseq_t * const iseq)
 {
+    if (rb_warn_check(ec, iseq)) return;
+
     VALUE name, loc;
     name = rb_id2str(ci->mid);
     loc = rb_iseq_location(iseq);
@@ -636,8 +685,10 @@ rb_warn_split_last_hash_to_keyword(struct rb_calling_info *calling, const struct
 }
 
 static inline void
-rb_warn_last_hash_to_keyword(struct rb_calling_info *calling, const struct rb_call_info *ci, const rb_iseq_t * const iseq)
+rb_warn_last_hash_to_keyword(rb_execution_context_t * const ec, struct rb_calling_info *calling, const struct rb_call_info *ci, const rb_iseq_t * const iseq)
 {
+    if (rb_warn_check(ec, iseq)) return;
+
     VALUE name, loc;
     name = rb_id2str(ci->mid);
     loc = rb_iseq_location(iseq);
@@ -766,7 +817,7 @@ setup_parameters_complex(rb_execution_context_t * const ec, const rb_iseq_t * co
                     }
                 }
                 else {
-                    rb_warn_keyword_to_last_hash(calling, ci, iseq);
+                    rb_warn_keyword_to_last_hash(ec, calling, ci, iseq);
                 }
 	    }
             else if (!remove_empty_keyword_hash && rest_last) {
@@ -789,7 +840,7 @@ setup_parameters_complex(rb_execution_context_t * const ec, const rb_iseq_t * co
                     }
                 }
                 else {
-                    rb_warn_keyword_to_last_hash(calling, ci, iseq);
+                    rb_warn_keyword_to_last_hash(ec, calling, ci, iseq);
                 }
 	    }
             else if (!remove_empty_keyword_hash) {
@@ -856,10 +907,10 @@ setup_parameters_complex(rb_execution_context_t * const ec, const rb_iseq_t * co
                 }
                 else if (check_only_symbol) {
                     if (keyword_hash != Qnil) {
-                        rb_warn_split_last_hash_to_keyword(calling, ci, iseq);
+                        rb_warn_split_last_hash_to_keyword(ec, calling, ci, iseq);
                     }
                     else {
-                        rb_warn_keyword_to_last_hash(calling, ci, iseq);
+                        rb_warn_keyword_to_last_hash(ec, calling, ci, iseq);
                     }
                 }
             }
@@ -868,15 +919,15 @@ setup_parameters_complex(rb_execution_context_t * const ec, const rb_iseq_t * co
                  * def foo(k:1) p [k]; end
                  * foo({k:42}) #=> 42
                  */
-                rb_warn_last_hash_to_keyword(calling, ci, iseq);
+                rb_warn_last_hash_to_keyword(ec, calling, ci, iseq);
                 given_argc--;
             }
             else if (keyword_hash != Qnil) {
-                rb_warn_split_last_hash_to_keyword(calling, ci, iseq);
+                rb_warn_split_last_hash_to_keyword(ec, calling, ci, iseq);
             }
         }
         else if (given_argc == min_argc && kw_flag) {
-            rb_warn_keyword_to_last_hash(calling, ci, iseq);
+            rb_warn_keyword_to_last_hash(ec, calling, ci, iseq);
         }
     }