C++ IR: Translate ErrorExpr to NoOp

Author: jbj

cpp/ql/src/semmle/code/cpp/ir/implementation/raw/internal/TranslatedExpr.qll

@@ -2862,3 +2862,36 @@ class TranslatedStmtExpr extends TranslatedNonConstantExpr {
     result = getTranslatedStmt(expr.getStmt())
   }
 }
+
+class TranslatedErrorExpr extends TranslatedSingleInstructionExpr {
+  override ErrorExpr expr;
+
+  TranslatedErrorExpr() {
+    // The extractor deliberately emits an `ErrorExpr` as the first argument to
+    // the allocator call, if any, of a `NewOrNewArrayExpr`. That `ErrorExpr`
+    // should not be translated.
+    not exists(NewOrNewArrayExpr new | expr = new.getAllocatorCall().getArgument(0))
+  }
+
+  override final Instruction getFirstInstruction() {
+    result = getInstruction(OnlyInstructionTag())
+  }
+
+  override final TranslatedElement getChild(int id) { none() }
+
+  override final Instruction getInstructionSuccessor(InstructionTag tag, EdgeKind kind) {
+    tag = OnlyInstructionTag() and
+    result = getParent().getChildSuccessor(this) and
+    kind instanceof GotoEdge
+  }
+
+  override final Instruction getChildSuccessor(TranslatedElement child) { none() }
+
+  override final Instruction getInstructionOperand(InstructionTag tag, OperandTag operandTag) {
+    none()
+  }
+
+  override final Opcode getOpcode() {
+    result instanceof Opcode::NoOp
+  }
+}

cpp/ql/test/library-tests/ir/ir/aliased_ssa_sanity.expected

@@ -4,7 +4,6 @@ duplicateOperand
 missingPhiOperand
 missingOperandType
 instructionWithoutSuccessor
-| bad_asts.cpp:30:8:30:16 | UnmodeledDefinition: errorExpr |
 ambiguousSuccessors
 unexplainedLoop
 unnecessaryPhiInstruction

cpp/ql/test/library-tests/ir/ir/raw_ir.expected

@@ -50,25 +50,22 @@ bad_asts.cpp:
 
 #   30| void Bad::errorExpr()
 #   30|   Block 0
-#   30|     v0_0(void)     = EnterFunction       : 
-#   30|     mu0_1(unknown) = AliasedDefinition   : 
-#   30|     mu0_2(unknown) = UnmodeledDefinition : 
-
-#-----|   Block 1
-#-----|     r1_0(error)      = Load               : ~mu0_2
-#   33|     r1_1(glval<int>) = VariableAddress[x] : 
-#   33|     mu1_2(int)       = Store              : &:r1_1, r1_0
-#   34|     v1_3(void)       = NoOp               : 
-#   30|     v1_4(void)       = ReturnVoid         : 
-#   30|     v1_5(void)       = UnmodeledUse       : mu*
-#   30|     v1_6(void)       = ExitFunction       : 
-
-#-----|   Block 2
-#-----|     r2_0(error)      = Load               : ~mu0_2
-#   32|     r2_1(glval<int>) = VariableAddress[x] : 
-
-#   32|   Block 3
-#   32|     mu3_0(int) = Store : &:r2_1
+#   30|     v0_0(void)         = EnterFunction       : 
+#   30|     mu0_1(unknown)     = AliasedDefinition   : 
+#   30|     mu0_2(unknown)     = UnmodeledDefinition : 
+#-----|     r0_3(glval<error>) = NoOp                : 
+#-----|     r0_4(error)        = Load                : &:r0_3, ~mu0_2
+#   32|     r0_5(glval<int>)   = VariableAddress[x]  : 
+#   32|     r0_6(error)        = NoOp                : 
+#   32|     mu0_7(int)         = Store               : &:r0_5, r0_6
+#-----|     r0_8(glval<error>) = NoOp                : 
+#-----|     r0_9(error)        = Load                : &:r0_8, ~mu0_2
+#   33|     r0_10(glval<int>)  = VariableAddress[x]  : 
+#   33|     mu0_11(int)        = Store               : &:r0_10, r0_9
+#   34|     v0_12(void)        = NoOp                : 
+#   30|     v0_13(void)        = ReturnVoid          : 
+#   30|     v0_14(void)        = UnmodeledUse        : mu*
+#   30|     v0_15(void)        = ExitFunction        : 
 
 clang.cpp:
 #    5| int* globalIntAddress()

cpp/ql/test/library-tests/ir/ir/raw_sanity.expected

@@ -1,15 +1,9 @@
 missingOperand
-| bad_asts.cpp:32:12:32:16 | Store: <error expr> | Instruction 'Store' is missing an expected operand with tag 'StoreValue' in function '$@'. | bad_asts.cpp:30:8:30:16 | IR: errorExpr | void Bad::errorExpr() |
-| file://:0:0:0:0 | Load: <error expr> | Instruction 'Load' is missing an expected operand with tag 'Address' in function '$@'. | bad_asts.cpp:30:8:30:16 | IR: errorExpr | void Bad::errorExpr() |
-| file://:0:0:0:0 | Load: <error expr> | Instruction 'Load' is missing an expected operand with tag 'Address' in function '$@'. | bad_asts.cpp:30:8:30:16 | IR: errorExpr | void Bad::errorExpr() |
 unexpectedOperand
 duplicateOperand
 missingPhiOperand
 missingOperandType
 instructionWithoutSuccessor
-| bad_asts.cpp:30:8:30:16 | UnmodeledDefinition: errorExpr |
-| bad_asts.cpp:32:9:32:9 | VariableAddress: definition of x |
-| bad_asts.cpp:32:12:32:16 | Store: <error expr> |
 ambiguousSuccessors
 unexplainedLoop
 unnecessaryPhiInstruction

cpp/ql/test/library-tests/ir/ir/unaliased_ssa_sanity.expected

@@ -4,7 +4,6 @@ duplicateOperand
 missingPhiOperand
 missingOperandType
 instructionWithoutSuccessor
-| bad_asts.cpp:30:8:30:16 | UnmodeledDefinition: errorExpr |
 ambiguousSuccessors
 unexplainedLoop
 unnecessaryPhiInstruction