compiler: deref receiver types in mangled names

This was the original intent, as reflected in the long comment at the
    start of names.cc, but I forgot to implement it.
    
    Also, remove a leading ".0" from the final name.  That could occur for
    a method whose receiver type starts with 'u', as in that case we
    prepend a space to the mangled name, to avoid confusion with the
    Unicode mangling, and the space turns into ".0".
    
    Also, if the Unicode encoding would cause the final to start with
    "..u" or "..U", add a leading underscore.
    
    Patch gotest to not get fooled by some names.
    
    The result of these changes is that all symbols start with a letter or
    an underscore.
    
    Reviewed-on: https://go-review.googlesource.com/90015

From-SVN: r257068

gcc/go/gofrontend/MERGE

@@ -1,4 +1,4 @@
-553e04735d1be372c596c720bcaea27e050b13a6
+203cbe7d3820fa03c965a01f72461f71588fe952
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

gcc/go/gofrontend/go-encode-id.cc

@@ -104,6 +104,14 @@ go_encode_id(const std::string &id)
   std::string ret;
   const char* p = id.c_str();
   const char* pend = p + id.length();
+
+  // A leading ".0" is a space introduced before a mangled type name
+  // that starts with a 'u' or 'U', to avoid confusion with the
+  // mangling used here.  We don't need a leading ".0", and we don't
+  // want symbols that start with '.', so remove it.
+  if (p[0] == '.' && p[1] == '0')
+    p += 2;
+
   while (p < pend)
     {
       unsigned int c;
@@ -115,16 +123,19 @@ go_encode_id(const std::string &id)
 	  go_assert(!char_needs_encoding(c));
 	  ret += c;
 	}
-      else if (c < 0x10000)
-	{
-	  char buf[16];
-	  snprintf(buf, sizeof buf, "..u%04x", c);
-	  ret += buf;
-	}
       else
 	{
 	  char buf[16];
-	  snprintf(buf, sizeof buf, "..U%08x", c);
+	  if (c < 0x10000)
+	    snprintf(buf, sizeof buf, "..u%04x", c);
+	  else
+	    snprintf(buf, sizeof buf, "..U%08x", c);
+
+	  // We don't want a symbol to start with '.', so add a prefix
+	  // if needed.
+	  if (ret.empty())
+	    ret += '_';
+
 	  ret += buf;
 	}
       p += len;

gcc/go/gofrontend/names.cc

@@ -213,7 +213,7 @@ Gogo::function_asm_name(const std::string& go_name, const Package* package,
 {
   std::string ret;
   if (rtype != NULL)
-    ret = rtype->mangled_name(this);
+    ret = rtype->deref()->mangled_name(this);
   else if (package == NULL)
     ret = this->pkgpath_symbol();
   else
@@ -892,14 +892,7 @@ Named_type::append_mangled_type_name(Gogo* gogo, bool use_alias,
 	  const Typed_identifier* rcvr =
 	    this->in_function_->func_value()->type()->receiver();
 	  if (rcvr != NULL)
-	    {
-	      std::string m = rcvr->type()->mangled_name(gogo);
-	      // Turn a leading ".1" back into "*" since we are going
-	      // to type-mangle this name again.
-	      if (m.compare(0, 2, ".1") == 0)
-		m = "*" + m.substr(2);
-	      ret->append(m);
-	    }
+	    ret->append(rcvr->type()->deref()->mangled_name(gogo));
 	  else if (this->in_function_->package() == NULL)
 	    ret->append(gogo->pkgpath_symbol());
 	  else
@@ -956,7 +949,7 @@ Gogo::type_descriptor_name(Type* type, Named_type* nt)
 	  const Typed_identifier* rcvr =
 	    in_function->func_value()->type()->receiver();
 	  if (rcvr != NULL)
-	    ret.append(rcvr->type()->mangled_name(this));
+	    ret.append(rcvr->type()->deref()->mangled_name(this));
 	  else if (in_function->package() == NULL)
 	    ret.append(this->pkgpath_symbol());
 	  else

libgo/go/runtime/pprof/pprof_test.go

@@ -730,7 +730,7 @@ func TestMutexProfile(t *testing.T) {
 		stks := stacks(p)
 		for _, want := range [][]string{
 			// {"sync.(*Mutex).Unlock", "pprof.blockMutex.func1"},
-			{".1sync.Mutex.Unlock", "pprof.blockMutex..func1"},
+			{"sync.Mutex.Unlock", "pprof.blockMutex..func1"},
 		} {
 			if !containsStack(stks, want) {
 				t.Errorf("No matching stack entry for %+v", want)

libgo/testsuite/gotest

@@ -518,7 +518,7 @@ localname() {
 	pattern='Test([^a-z].*)?'
 	# The -p option tells GNU nm not to sort.
 	# The -v option tells Solaris nm to sort by value.
-	tests=$($NM -p -v _gotest_.o $xofile | egrep " $text .*\."$pattern'$' | grep -v '\..*\..*\.' | fgrep -v '$' | fgrep -v ' __go_' | sed 's/.* //' | $symtogo)
+	tests=$($NM -p -v _gotest_.o $xofile | egrep " $text .*\."$pattern'$' | grep -v '\..*\.' | fgrep -v '$' | fgrep -v ' __go_' | sed 's/.* //' | $symtogo)
 	if [ "x$tests" = x ]; then
 		echo 'gotest: warning: no tests matching '$pattern in _gotest_.o $xofile 1>&2
 		exit 2