C++: Add a new 'Location.isBefore' predicate that also considers columns.

cpp/ql/lib/semmle/code/cpp/Location.qll

@@ -73,8 +73,24 @@ class Location extends @location {
 
   /** Holds if `this` comes on a line strictly before `l`. */
   pragma[inline]
-  predicate isBefore(Location l) {
-    this.getFile() = l.getFile() and this.getEndLine() < l.getStartLine()
+  predicate isBefore(Location l) { isBefore(l, false) }
+
+  /**
+   * Holds if `this` comes strictly before `l`. The boolean `sameLine` is
+   * true if `l` is on the same line as `this`, but starts at a later column.
+   * Otherwise, `sameLine` is false.
+   */
+  pragma[inline]
+  predicate isBefore(Location l, boolean sameLine) {
+    this.getFile() = l.getFile() and
+    (
+      sameLine = false and
+      this.getEndLine() < l.getStartLine()
+      or
+      sameLine = true and
+      this.getEndLine() = l.getStartLine() and
+      this.getEndColumn() < l.getStartColumn()
+    )
   }
 
   /** Holds if location `l` is completely contained within this one. */

cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/internal/IRConstruction.qll

@@ -349,7 +349,7 @@ Instruction getInstructionBackEdgeSuccessor(Instruction instruction, EdgeKind ki
 
 /** Holds if `goto` jumps strictly forward in the program text. */
 private predicate isStrictlyForwardGoto(GotoStmt goto) {
-  goto.getLocation().isBefore(goto.getTarget().getLocation())
+  goto.getLocation().isBefore(goto.getTarget().getLocation(), _)
 }
 
 Locatable getInstructionAst(TStageInstruction instr) {