[gcc/devel/rust/master] Ensure we support generic arguments on mangled type-paths

[gcc/devel/rust/master] Ensure we support generic arguments on mangled type-paths

[Thomas Schwinge]

https://gcc.gnu.org/g:1282974cf899f9486c62054bcbadf41346915dd5

commit 1282974cf899f9486c62054bcbadf41346915dd5
Author: Philip Herron <philip.herron@embecosm.com>
Date:   Wed Jun 29 12:01:05 2022 +0100

    Ensure we support generic arguments on mangled type-paths
    
    This allows us to have the generic arguments within type paths for mangled
    symbols such as those in impl-blocks. This also updates our symbol
    managling to mangle comma's to $C$.

Diff:
---
 gcc/rust/backend/rust-mangle.cc           |  6 ++++
 gcc/rust/resolve/rust-ast-resolve-type.cc | 47 ++++++++++++++++++++++++++++++-
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/gcc/rust/backend/rust-mangle.cc b/gcc/rust/backend/rust-mangle.cc
index c0aea0286af..4d202078a70 100644
--- a/gcc/rust/backend/rust-mangle.cc
+++ b/gcc/rust/backend/rust-mangle.cc
@@ -14,6 +14,7 @@ static const std::string kMangledPtr = "$BP$";
 static const std::string kMangledLeftSqParen = "$u5b$";	 // [
 static const std::string kMangledRightSqParen = "$u5d$"; // ]
 static const std::string kQualPathBegin = "_" + kMangledSubstBegin;
+static const std::string kMangledComma = "$C$";
 
 namespace Rust {
 namespace Compile {
@@ -39,6 +40,9 @@ legacy_mangle_name (const std::string &name)
   //
   // example::Foo<T>::new:
   // _ZN7example12Foo$LT$T$GT$3new17h9a2aacb7fd783515E:
+  //
+  // <example::Identity as example::FnLike<&T,&T>>::call
+  // _ZN74_$LT$example..Identity$u20$as$u20$example..FnLike$LT$$RF$T$C$$RF$T$GT$$GT$4call17ha9ee58935895acb3E
 
   std::string buffer;
   for (size_t i = 0; i < name.size (); i++)
@@ -62,6 +66,8 @@ legacy_mangle_name (const std::string &name)
 	m = kMangledLeftSqParen;
       else if (c == ']')
 	m = kMangledRightSqParen;
+      else if (c == ',')
+	m = kMangledComma;
       else if (c == ':')
 	{
 	  rust_assert (i + 1 < name.size ());
diff --git a/gcc/rust/resolve/rust-ast-resolve-type.cc b/gcc/rust/resolve/rust-ast-resolve-type.cc
index 5d0ceb536d5..a823543e18d 100644
--- a/gcc/rust/resolve/rust-ast-resolve-type.cc
+++ b/gcc/rust/resolve/rust-ast-resolve-type.cc
@@ -356,7 +356,52 @@ ResolveTypeToCanonicalPath::visit (AST::TypePath &path)
   if (mappings->lookup_canonical_path (mappings->get_current_crate (),
 				       resolved_node, &type_path))
     {
-      result = *type_path;
+      auto &final_seg = path.get_segments ().back ();
+      switch (final_seg->get_type ())
+	{
+	  case AST::TypePathSegment::SegmentType::GENERIC: {
+	    AST::TypePathSegmentGeneric *s
+	      = static_cast<AST::TypePathSegmentGeneric *> (final_seg.get ());
+
+	    std::vector<CanonicalPath> args;
+	    if (s->has_generic_args ())
+	      {
+		for (auto &gt : s->get_generic_args ().get_type_args ())
+		  {
+		    CanonicalPath arg = CanonicalPath::create_empty ();
+		    bool ok = ResolveTypeToCanonicalPath::go (gt.get (), arg);
+		    if (ok)
+		      args.push_back (std::move (arg));
+		  }
+	      }
+
+	    result = *type_path;
+	    if (!args.empty ())
+	      {
+		// append this onto the path
+		std::string buf;
+		for (size_t i = 0; i < args.size (); i++)
+		  {
+		    bool has_next = (i + 1) < args.size ();
+		    const auto &arg = args.at (i);
+
+		    buf += arg.get ();
+		    if (has_next)
+		      buf += ", ";
+		  }
+
+		std::string arg_seg = "<" + buf + ">";
+		CanonicalPath argument_seg
+		  = CanonicalPath::new_seg (s->get_node_id (), arg_seg);
+		result = result.append (argument_seg);
+	      }
+	  }
+	  break;
+
+	default:
+	  result = *type_path;
+	  break;
+	}
     }
 }