M0-1-2: Remove reference to GuardCondition

In the upgrade to 2.16.6 GuardCondition has been modified to use
the IR instead of the AST mode it used before. One of the
consequences of this change is that GuardConditions no longer exist
for uninstantiated templates (because the IR does not apply for
uninstantiated templates).

Instead of using GuardCondition we can use the same logic for
deducing infeasible paths for uninstantiated templates as for non
template code. This avoids the dependency on GuardCondition, and
provides consistency with the rest of the query, while shortening
the query.

Author: lcartey

change_notes/2024-10-08-upgrade-to-2.16.6.md

@@ -1 +1,3 @@
-- Updated the CodeQL version to `2.16.6`.
+- Updated the CodeQL version to `2.16.6`.
+- `M0-1-2` - `InfeasiblePath.ql`:
+  - This query may now report additional results within templates where a relational operation is performed which has a constant value given the specified arguments.

cpp/autosar/src/rules/M0-1-2/InfeasiblePath.ql

@@ -151,186 +151,19 @@ predicate isConstantRelationalOperation(
  * Holds if the `ConditionalNode` has an infeasible `path` for the reason given in `explanation`.
  */
 predicate hasInfeasiblePath(ConditionalControlFlowNode node, string message) {
-  //deal with the infeasible in all uninstantiated templates separately
-  node.isFromUninstantiatedTemplate(_) and
-  node instanceof ConditionControllingUnreachable and
-  message = "The path is unreachable in a template."
-  or
   exists(boolean infeasiblePath, string explanation |
-    (
-      not node.isFromUninstantiatedTemplate(_) and
-      not node.isFromTemplateInstantiation(_) and
-      message = "The " + infeasiblePath + " path is infeasible because " + explanation + "."
-    ) and
-    (
-      hasCFGDeducedInfeasiblePath(node, infeasiblePath, explanation) and
-      not isConstantRelationalOperation(node, infeasiblePath, _)
-      or
-      isConstantRelationalOperation(node, infeasiblePath, explanation)
-    )
+    not node.isFromTemplateInstantiation(_) and
+    if node.isFromUninstantiatedTemplate(_)
+    then message = "The path is unreachable in a template."
+    else message = "The " + infeasiblePath + " path is infeasible because " + explanation + "."
+  |
+    hasCFGDeducedInfeasiblePath(node, infeasiblePath, explanation) and
+    not isConstantRelationalOperation(node, infeasiblePath, _)
+    or
+    isConstantRelationalOperation(node, infeasiblePath, explanation)
   )
 }
 
-/**
- * A newtype representing "unreachable" blocks in the program. We use a newtype here to avoid
- * reporting the same block in multiple `Function` instances created from one function in a template.
- */
-private newtype TUnreachableBasicBlock =
-  TUnreachableNonTemplateBlock(BasicBlock bb) {
-    bb.isUnreachable() and
-    // Exclude anything template related from this case
-    not bb.getEnclosingFunction().isFromTemplateInstantiation(_) and
-    not bb.getEnclosingFunction().isFromUninstantiatedTemplate(_) and
-    // Exclude compiler generated basic blocks
-    not isCompilerGenerated(bb)
-  } or
-  /**
-   * A `BasicBlock` that occurs in at least one `Function` instance for a template. `BasicBlock`s
-   * are matched up across templates by location.
-   */
-  TUnreachableTemplateBlock(
-    string filepath, int startline, int startcolumn, int endline, int endcolumn,
-    GuardCondition uninstantiatedGuardCondition
-  ) {
-    exists(BasicBlock bb |
-      // BasicBlock occurs in this location
-      bb.hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn) and
-      // And is contained in the `uninstantiatedFunction` only
-      // not from anything constructed from it
-      // because we want infeasible paths independent of parameters
-      exists(Function enclosing | enclosing = bb.getEnclosingFunction() |
-        //guard is in the template function
-        (
-          enclosing.getBlock().getAChild*() = uninstantiatedGuardCondition and
-          //function template
-          enclosing.isFromUninstantiatedTemplate(_) and
-          uninstantiatedGuardCondition.isFromUninstantiatedTemplate(_) and
-          //true condition is unreachable: basic block starts on same line as guard
-          (
-            not exists(uninstantiatedGuardCondition.getATrueSuccessor()) and
-            bb.hasLocationInfo(filepath, uninstantiatedGuardCondition.getLocation().getStartLine(),
-              startcolumn, endline, endcolumn)
-            or
-            //false condition is unreachable: false basic block starts on one line after its true basic block
-            not exists(uninstantiatedGuardCondition.getAFalseSuccessor()) and
-            bb.hasLocationInfo(filepath,
-              uninstantiatedGuardCondition.getATrueSuccessor().getLocation().getEndLine() + 1,
-              startcolumn, endline, endcolumn)
-          )
-        )
-      ) and
-      // And is unreachable
-      bb.isUnreachable() and
-      // //Exclude compiler generated control flow nodes
-      not isCompilerGenerated(bb) and
-      //Exclude nodes affected by macros, because our find-the-same-basic-block-by-location doesn't
-      //work in that case
-      not bb.(ControlFlowNode).isAffectedByMacro()
-    )
-  }
-
-/**
- * An unreachable basic block.
- */
-class UnreachableBasicBlock extends TUnreachableBasicBlock {
-  /** Gets a `BasicBlock` which is represented by this set of unreachable basic blocks. */
-  BasicBlock getABasicBlock() { none() }
-
-  /** Gets a `GuardCondition` instance which we treat as the original GuardCondition. */
-  GuardCondition getGuardCondition() { none() }
-
-  predicate hasLocationInfo(
-    string filepath, int startline, int startcolumn, int endline, int endcolumn
-  ) {
-    none()
-  }
-
-  string toString() { result = "default" }
-}
-
-/**
- * A non-templated unreachable basic block.
- */
-class UnreachableNonTemplateBlock extends UnreachableBasicBlock, TUnreachableNonTemplateBlock {
-  BasicBlock getBasicBlock() { this = TUnreachableNonTemplateBlock(result) }
-
-  override BasicBlock getABasicBlock() { result = getBasicBlock() }
-
-  override GuardCondition getGuardCondition() { result.controls(getBasicBlock(), true) }
-
-  override predicate hasLocationInfo(
-    string filepath, int startline, int startcolumn, int endline, int endcolumn
-  ) {
-    getBasicBlock().hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn)
-  }
-
-  override string toString() { result = getBasicBlock().toString() }
-}
-
-/**
- * A templated unreachable basic block.
- */
-class UnreachableTemplateBlock extends UnreachableBasicBlock, TUnreachableTemplateBlock {
-  override BasicBlock getABasicBlock() {
-    exists(
-      string filepath, int startline, int startcolumn, int endline, int endcolumn,
-      GuardCondition uninstantiatedGuardCondition
-    |
-      this =
-        TUnreachableTemplateBlock(filepath, startline, startcolumn, endline, endcolumn,
-          uninstantiatedGuardCondition) and
-      result.hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn) and
-      exists(Function enclosing |
-        //guard is in the template function
-        (
-          enclosing.getBlock().getAChild*() = uninstantiatedGuardCondition and
-          //function template
-          enclosing.isFromUninstantiatedTemplate(_) and
-          uninstantiatedGuardCondition.isFromUninstantiatedTemplate(_) and
-          //true condition is unreachable: basic block starts on same line as guard
-          (
-            not exists(uninstantiatedGuardCondition.getATrueSuccessor()) and
-            this.hasLocationInfo(filepath,
-              uninstantiatedGuardCondition.getLocation().getStartLine(), startcolumn, endline,
-              endcolumn)
-            or
-            //false condition is unreachable: false basic block starts on one line after its true basic block
-            not exists(uninstantiatedGuardCondition.getAFalseSuccessor()) and
-            this.hasLocationInfo(filepath,
-              uninstantiatedGuardCondition.getATrueSuccessor().getLocation().getEndLine() + 1,
-              startcolumn, endline, endcolumn)
-          )
-        )
-      )
-    |
-      result.isUnreachable() and
-      // Exclude compiler generated control flow nodes
-      not isCompilerGenerated(result) and
-      // Exclude nodes affected by macros, because our find-the-same-basic-block-by-location doesn't
-      // work in that case
-      not result.(ControlFlowNode).isAffectedByMacro()
-    )
-  }
-
-  override GuardCondition getGuardCondition() {
-    this = TUnreachableTemplateBlock(_, _, _, _, _, result)
-  }
-
-  override predicate hasLocationInfo(
-    string filepath, int startline, int startcolumn, int endline, int endcolumn
-  ) {
-    this = TUnreachableTemplateBlock(filepath, startline, startcolumn, endline, endcolumn, _)
-  }
-
-  override string toString() { result = getABasicBlock().toString() }
-}
-
-class ConditionControllingUnreachable extends GuardCondition {
-  ConditionControllingUnreachable() {
-    exists(UnreachableTemplateBlock b | this = b.getGuardCondition())
-  }
-}
-
 from ConditionalControlFlowNode cond, string explanation
 where
   not isExcluded(cond, DeadCodePackage::infeasiblePathQuery()) and