Revert "Revert "SSA: Turn consistency predicates into query predicates""

csharp/ql/consistency-queries/SsaConsistency.ql

@@ -1,23 +1,15 @@
 import csharp
-import semmle.code.csharp.dataflow.internal.SsaImpl::Consistency as Consistency
+import semmle.code.csharp.dataflow.internal.SsaImpl::Consistency
 import Ssa
 
-class MyRelevantDefinition extends Consistency::RelevantDefinition, Ssa::Definition {
+class MyRelevantDefinition extends RelevantDefinition, Ssa::Definition {
   override predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
   ) {
     this.getLocation().hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)
   }
 }
 
-query predicate nonUniqueDef = Consistency::nonUniqueDef/4;
-
-query predicate readWithoutDef = Consistency::readWithoutDef/3;
-
-query predicate deadDef = Consistency::deadDef/2;
-
-query predicate notDominatedByDef = Consistency::notDominatedByDef/4;
-
 query predicate localDeclWithSsaDef(LocalVariableDeclExpr d) {
   // Local variables in C# must be initialized before every use, so uninitialized
   // local variables should not have an SSA definition, as that would imply that

ruby/ql/consistency-queries/SsaConsistency.ql

@@ -1,18 +1,10 @@
 import codeql.ruby.dataflow.SSA
-import codeql.ruby.dataflow.internal.SsaImpl::Consistency as Consistency
+import codeql.ruby.dataflow.internal.SsaImpl::Consistency
 
-class MyRelevantDefinition extends Consistency::RelevantDefinition, Ssa::Definition {
+class MyRelevantDefinition extends RelevantDefinition, Ssa::Definition {
   override predicate hasLocationInfo(
     string filepath, int startline, int startcolumn, int endline, int endcolumn
   ) {
     this.getLocation().hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)
   }
 }
-
-query predicate nonUniqueDef = Consistency::nonUniqueDef/4;
-
-query predicate readWithoutDef = Consistency::readWithoutDef/3;
-
-query predicate deadDef = Consistency::deadDef/2;
-
-query predicate notDominatedByDef = Consistency::notDominatedByDef/4;

shared/ssa/codeql/ssa/Ssa.qll

@@ -9,7 +9,10 @@ signature module InputSig {
    * A basic block, that is, a maximal straight-line sequence of control flow nodes
    * without branches or joins.
    */
-  class BasicBlock;
+  class BasicBlock {
+    /** Gets a textual representation of this basic block. */
+    string toString();
+  }
 
   /**
    * Gets the basic block that immediately dominates basic block `bb`, if any.
@@ -43,7 +46,10 @@ signature module InputSig {
   class ExitBasicBlock extends BasicBlock;
 
   /** A variable that can be SSA converted. */
-  class SourceVariable;
+  class SourceVariable {
+    /** Gets a textual representation of this variable. */
+    string toString();
+  }
 
   /**
    * Holds if the `i`th node of basic block `bb` is a (potential) write to source
@@ -846,8 +852,6 @@ module Make<InputSig Input> {
   }
 
   /** Provides a set of consistency queries. */
-  // TODO: Make these `query` predicates once class signatures are supported
-  // (`SourceVariable` and `BasicBlock` must have `toString`)
   module Consistency {
     /** A definition that is relevant for the consistency queries. */
     abstract class RelevantDefinition extends Definition {
@@ -858,27 +862,27 @@ module Make<InputSig Input> {
     }
 
     /** Holds if a read can be reached from multiple definitions. */
-    predicate nonUniqueDef(RelevantDefinition def, SourceVariable v, BasicBlock bb, int i) {
+    query predicate nonUniqueDef(RelevantDefinition def, SourceVariable v, BasicBlock bb, int i) {
       ssaDefReachesRead(v, def, bb, i) and
       not exists(unique(Definition def0 | ssaDefReachesRead(v, def0, bb, i)))
     }
 
     /** Holds if a read cannot be reached from a definition. */
-    predicate readWithoutDef(SourceVariable v, BasicBlock bb, int i) {
+    query predicate readWithoutDef(SourceVariable v, BasicBlock bb, int i) {
       variableRead(bb, i, v, _) and
       not ssaDefReachesRead(v, _, bb, i)
     }
 
     /** Holds if a definition cannot reach a read. */
-    predicate deadDef(RelevantDefinition def, SourceVariable v) {
+    query predicate deadDef(RelevantDefinition def, SourceVariable v) {
       v = def.getSourceVariable() and
       not ssaDefReachesRead(_, def, _, _) and
       not phiHasInputFromBlock(_, def, _) and
       not uncertainWriteDefinitionInput(_, def)
     }
 
     /** Holds if a read is not dominated by a definition. */
-    predicate notDominatedByDef(RelevantDefinition def, SourceVariable v, BasicBlock bb, int i) {
+    query predicate notDominatedByDef(RelevantDefinition def, SourceVariable v, BasicBlock bb, int i) {
       exists(BasicBlock bbDef, int iDef | def.definesAt(v, bbDef, iDef) |
         ssaDefReachesReadWithinBlock(v, def, bb, i) and
         (bb != bbDef or i < iDef)