Go patch committed: Don't export function descriptors for unexported names

Message ID CAOyqgcWV7NzAxCWLQz87eKr0K3Wx3Pw64jX7Q_fm1CVM5BZfQA@mail.gmail.com
State New
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  • Go patch committed: Don't export function descriptors for unexported names
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Commit Message

Ian Lance Taylor Feb. 13, 2018, 9:15 p.m.
The patch changes the Go frontend to not export function descriptors
for unexported names.  They aren't needed, and could potentially cause
unlikely symbol name collisions.  Also, the runtime package's
reference to main could cause the runtime package to define
main.main..f, which could also be defined in the main package if it
does something like fmt.Print(main).  That will normally work but will
fail with a multiple symbol definition error when using -static-libgo.
Bootstrapped and ran Go testsuite on x86_64-pc-linux-gnu.  Committed
to mainline.

Ian

Patch

Index: gcc/go/gofrontend/MERGE
===================================================================
--- gcc/go/gofrontend/MERGE	(revision 257600)
+++ gcc/go/gofrontend/MERGE	(working copy)
@@ -1,4 +1,4 @@ 
-7998e29eec43ede1cee925d87eef0b09da67d90b
+5d5ea2fd05dbf369ccc53c93d4846623cdea0c47
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
Index: gcc/go/gofrontend/expressions.cc
===================================================================
--- gcc/go/gofrontend/expressions.cc	(revision 257527)
+++ gcc/go/gofrontend/expressions.cc	(working copy)
@@ -1330,9 +1330,24 @@  Func_descriptor_expression::do_get_backe
   else
     {
       Location bloc = Linemap::predeclared_location();
+
+      // The runtime package has hash/equality functions that are
+      // referenced by type descriptors outside of the runtime, so the
+      // function descriptors must be visible even though they are not
+      // exported.
+      bool is_exported_runtime = false;
+      if (gogo->compiling_runtime()
+	  && gogo->package_name() == "runtime"
+	  && (no->name().find("hash") != std::string::npos
+	      || no->name().find("equal") != std::string::npos))
+	is_exported_runtime = true;
+
       bool is_hidden = ((no->is_function()
 			 && no->func_value()->enclosing() != NULL)
+			|| (Gogo::is_hidden_name(no->name())
+			    && !is_exported_runtime)
 			|| Gogo::is_thunk(no));
+
       bvar = context->backend()->immutable_struct(var_name, asm_name,
                                                   is_hidden, false,
 						  btype, bloc);