More cleanup of includes to reduce compilation times (#6037)

Similar to #6031, this PR implements suggestions from iwyu to reduce the number of includes in header files by introducing forward declarations and moving includes to source files.

1 files changed, 10 insertions, 4 deletions

diff --git a/src/smt/expand_definitions.h b/src/smt/expand_definitions.h
index 486aa0c3a..0c2f9b2d5 100644
--- a/src/smt/expand_definitions.h
+++ b/src/smt/expand_definitions.h
@@ -20,17 +20,23 @@
 #include <unordered_map>
 
 #include "expr/node.h"
-#include "expr/term_conversion_proof_generator.h"
-#include "preprocessing/assertion_pipeline.h"
-#include "smt/smt_engine_stats.h"
-#include "util/resource_manager.h"
+#include "theory/trust_node.h"
 
 namespace CVC4 {
 
+class ProofNodeManager;
+class ResourceManager;
 class SmtEngine;
+class TConvProofGenerator;
+
+namespace preprocessing {
+class AssertionPipeline;
+}
 
 namespace smt {
 
+struct SmtEngineStatistics;
+
 /**
  * Module in charge of expanding definitions for an SMT engine.
  *