From e0421dbf536230046c5ac20e502df469d47630f4 Mon Sep 17 00:00:00 2001
From: Anders Schack-Mulligen <aschackmull@github.com>
Date: Tue, 28 Apr 2026 13:38:14 +0200
Subject: [PATCH] C#: Reinstate toString for SSA data flow nodes.

---
 csharp/ql/lib/semmle/code/csharp/dataflow/SSA.qll  | 14 --------------
 .../code/csharp/dataflow/internal/SsaImpl.qll      |  4 ++++
 shared/ssa/codeql/ssa/Ssa.qll                      |  4 +++-
 3 files changed, 7 insertions(+), 15 deletions(-)

diff --git a/csharp/ql/lib/semmle/code/csharp/dataflow/SSA.qll b/csharp/ql/lib/semmle/code/csharp/dataflow/SSA.qll
index 4a7f774af07..c251a30b351 100644
--- a/csharp/ql/lib/semmle/code/csharp/dataflow/SSA.qll
+++ b/csharp/ql/lib/semmle/code/csharp/dataflow/SSA.qll
@@ -506,8 +506,6 @@ module Ssa {
     }
 
     override Element getElement() { result = ad.getElement() }
-
-    override string toString() { result = "SSA def(" + this.getSourceVariable() + ")" }
   }
 
   /**
@@ -551,12 +549,6 @@ module Ssa {
     final Callable getCallable() { result = this.getBasicBlock().getEnclosingCallable() }
 
     override Element getElement() { result = this.getCallable() }
-
-    override string toString() {
-      if this.getSourceVariable().getAssignable() instanceof LocalScopeVariable
-      then result = "SSA capture def(" + this.getSourceVariable() + ")"
-      else result = "SSA entry def(" + this.getSourceVariable() + ")"
-    }
   }
 
   /**
@@ -590,10 +582,6 @@ module Ssa {
 
     /** Gets the parameter that this entry definition represents. */
     Parameter getParameter() { result = p }
-
-    override string toString() {
-      result = "SSA param_default(" + pragma[only_bind_out](this.getParameter()) + ")"
-    }
   }
 
   /**
@@ -687,8 +675,6 @@ module Ssa {
     predicate hasInputFromBlock(Definition inp, BasicBlock bb) {
       inp = SsaImpl::phiHasInputFromBlock(this, bb)
     }
-
-    override string toString() { result = "SSA phi(" + this.getSourceVariable() + ")" }
   }
 
   /**
diff --git a/csharp/ql/lib/semmle/code/csharp/dataflow/internal/SsaImpl.qll b/csharp/ql/lib/semmle/code/csharp/dataflow/internal/SsaImpl.qll
index 6db089928e0..218b8c97717 100644
--- a/csharp/ql/lib/semmle/code/csharp/dataflow/internal/SsaImpl.qll
+++ b/csharp/ql/lib/semmle/code/csharp/dataflow/internal/SsaImpl.qll
@@ -78,6 +78,10 @@ module Ssa_ = Impl::MakeSsa<SsaInput>;
 
 class Definition = Impl::Definition;
 
+private class SsaDefinitionToStringProxy extends Definition {
+  override string toString() { result = this.(SsaDefinition).toString() }
+}
+
 deprecated class WriteDefinition = Impl::WriteDefinition;
 
 deprecated class UncertainWriteDefinition = Impl::UncertainWriteDefinition;
diff --git a/shared/ssa/codeql/ssa/Ssa.qll b/shared/ssa/codeql/ssa/Ssa.qll
index 8d6b960b283..861f797ed6d 100644
--- a/shared/ssa/codeql/ssa/Ssa.qll
+++ b/shared/ssa/codeql/ssa/Ssa.qll
@@ -1054,7 +1054,7 @@ module Make<
     /** A static single assignment (SSA) definition. */
     class SsaDefinition extends FinalDefinition {
       /** Gets a textual representation of this SSA definition. */
-      string toString() { result = super.toString() }
+      string toString() { result = "SSA def(" + this.getSourceVariable() + ")" }
 
       /**
        * Gets the control flow node of this SSA definition.
@@ -1207,6 +1207,8 @@ module Make<
      * a phi definition for `x` is inserted just before the call `puts x`.
      */
     class SsaPhiDefinition extends SsaDefinition instanceof PhiNode {
+      override string toString() { result = "SSA phi(" + this.getSourceVariable() + ")" }
+
       /** Holds if `inp` is an input to this phi definition along the edge originating in `bb`. */
       predicate hasInputFromBlock(SsaDefinition inp, BasicBlock bb) {
         phiHasInputFromBlockCached(this, inp, bb)