[generator] Improve generic type lookup (#552)

Fixes: #543
In commit 262743b we began stripping the arity from Cecil imported
types so that we wouldn't write invalid types like
``System.Collections.Generic.IList`1<string>``, in order to correctly
emit `System.Collections.Generic.IList<string>`.
However when we try to resolve these types in the `SymbolTable` we
only look at the type name, ignoring the generic type parameters. In
this case we are looking for `System.Collections.Generic.IList` but
the type is stored in the symbol table with the arity to disambiguate
types like ``Action`1`` and ``Action`2``. Therefore our lookup fails
because the table key is ``System.Collections.Generic.IList`1``.
For example, if we have `LibraryA.dll` with:
public class Foo : Java.Lang.Object {
public virtual void Bar (IList<string> p0) {…}
}
And we attempt to bind a `LibraryB.jar` which references
`LibraryA.dll`, overriding `Foo.Bar()`:
public class Foo2 : Foo {
public override void Bar (IList<string> p0) {…}
}
Then `Foo2.Bar()` would elicit a BG8800 warning:
warning BG8800: Unknown parameter type System.Collections.Generic.IList<System.String> in method Bar in managed type Foo2.
Fix type lookup so that if the type is not found in the `SymbolTable`
and there are generic type parameters, calculate the arity from the
generic type parameters and look in the table again.
That is, `System.Collections.Generic.IList<string>` is rechecked as
``System.Collections.Generic.IList`1``, which allows the type to be
found.

Author: jpobst

tools/generator/Java.Interop.Tools.Generator.ObjectModel/Symbols/SymbolTable.cs

@@ -260,7 +260,15 @@ public ISymbol Lookup (string java_type)
 if(all_symbols_cache==null)
 all_symbols_cache=newConcurrentDictionary<string,ISymbol>(symbols.Values.SelectMany(v =>v).GroupBy(s =>s.FullName).ToDictionary(s =>s.Key, s =>s.FirstOrDefault()));
 
-all_symbols_cache.TryGetValue(key,outsym);
+if(!all_symbols_cache.TryGetValue(key,outsym)){
+// We may be looking for a type like:
+// - System.Collections.Generic.IList<Java.Util.Locale.LanguageRange>
+// Our key is "System.Collections.Generic.IList", but it's stored in
+// the symbol table with the arity so we need to look for
+// "System.Collections.Generic.IList`1" to find a match
+key=AddArity(key,type_params);
+all_symbols_cache.TryGetValue(key,outsym);
+}
 }
 }
 ISymbolresult;
@@ -290,7 +298,32 @@ public ISymbol Lookup (string java_type)
 
 returnresult;
 }
-
+
+privatestringAddArity(stringkey,stringtypeParams)
+{
+if(string.IsNullOrWhiteSpace(typeParams)||!typeParams.StartsWith("<")||!typeParams.EndsWith(">"))
+returnkey;
+
+varnested_count=0;
+vararity=1;
+
+// Remove the outer <>
+typeParams=typeParams.Substring(1,typeParams.Length-2);
+
+foreach(varcintypeParams){
+if(c=='>')
+nested_count--;
+
+if(c=='<')
+nested_count++;
+
+if(nested_count==0&&c==',')
+arity++;
+}
+
+return$"{key}`{arity}";
+}
+
 publicvoidDump()
 {
 foreach(varpinsymbols){

tools/generator/Tests/Unit-Tests/SymbolTableTests.cs

@@ -0,0 +1,40 @@
+usingSystem;
+usingMonoDroid.Generation;
+usingNUnit.Framework;
+
+namespacegeneratortests
+{
+[TestFixture]
+publicclassSymbolTableTests
+{
+[Test]
+publicvoidFindGenericTypes()
+{
+vartable=newSymbolTable();
+
+varlist=newInterfaceGen(newGenBaseSupport{
+Name="System.Collections.Generic.IList`1",
+FullName="System.Collections.Generic.IList`1",
+JavaSimpleName="System.Collections.Generic.IList`1"
+});
+
+table.AddType(list);
+
+vardict=newInterfaceGen(newGenBaseSupport{
+Name="System.Collections.Generic.IDictionary`2",
+FullName="System.Collections.Generic.IDictionary`2",
+JavaSimpleName="System.Collections.Generic.IDictionary`2"
+});
+
+table.AddType(dict);
+
+Assert.AreEqual("System.Collections.Generic.IList`1",table.Lookup("System.Collections.Generic.IList<Java.Util.Locale.LanguageRange>").FullName);
+Assert.AreEqual("System.Collections.Generic.IList`1",table.Lookup("System.Collections.Generic.IList<List<Java.Util.Locale.LanguageRange>>").FullName);
+
+Assert.AreEqual("System.Collections.Generic.IDictionary`2",table.Lookup("System.Collections.Generic.IDictionary<string, Java.Util.Locale.LanguageRange>").FullName);
+Assert.AreEqual("System.Collections.Generic.IDictionary`2",table.Lookup("System.Collections.Generic.IDictionary<string, List<Java.Util.Locale.LanguageRange>>").FullName);
+
+Assert.AreEqual("System.Collections.Generic.IList`1",table.Lookup("System.Collections.Generic.IList<Dictionary<string, Java.Util.Locale.LanguageRange>>").FullName);
+}
+}
+}