proc,dwarf/godwarf: support parametric types with dictionaries

Change debug_info type reader and proc to convert parametric types into
their real types by reading the corresponding dictionary entry and
using the same method used for interfaces to retrieve the DIE from a
runtime._type address.

'2586e9b1'.

service/test/variables_test.go

@@ -1602,7 +1602,48 @@ func TestCgoEval(t *testing.T) {
 					t.Fatalf("Unexpected error. Expected %s got %s", tc.err.Error(), err.Error())
 				}
 			}
-
+		}
+	})
+}
+
+func TestEvalExpressionGenerics(t *testing.T) {
+	if !goversion.VersionAfterOrEqual(runtime.Version(), 1, 18) {
+		t.Skip("generics not supported")
+	}
+
+	testcases := [][]varTest{
+		// testfn[int, float32]
+		[]varTest{
+			{"arg1", true, "3", "", "int", nil},
+			{"arg2", true, "2.1", "", "float32", nil},
+			{"m", true, "map[float32]int [2.1: 3, ]", "", "map[float32]int", nil},
+		},
+
+		// testfn[*astruct, astruct]
+		[]varTest{
+			{"arg1", true, "*main.astruct {x: 0, y: 1}", "", "*main.astruct", nil},
+			{"arg2", true, "main.astruct {x: 2, y: 3}", "", "main.astruct", nil},
+			{"m", true, "map[main.astruct]*main.astruct [{x: 2, y: 3}: *{x: 0, y: 1}, ]", "", "map[main.astruct]*main.astruct", nil},
+		},
+	}
+
+	withTestProcess("testvariables_generic", t, func(p *proc.Target, fixture protest.Fixture) {
+		for i, tcs := range testcases {
+			assertNoError(p.Continue(), t, fmt.Sprintf("Continue() returned an error (%d)", i))
+			for _, tc := range tcs {
+				variable, err := evalVariable(p, tc.name, pnormalLoadConfig)
+				if tc.err == nil {
+					assertNoError(err, t, fmt.Sprintf("EvalExpression(%s) returned an error", tc.name))
+					assertVariable(t, variable, tc)
+				} else {
+					if err == nil {
+						t.Fatalf("Expected error %s, got no error (%s)", tc.err.Error(), tc.name)
+					}
+					if tc.err.Error() != err.Error() {
+						t.Fatalf("Unexpected error. Expected %s got %s", tc.err.Error(), err.Error())
+					}
+				}
+			}
 		}
 	})
 }