C++: Move getFullyConverted{Upper,Lower}Bounds

Rather than being public, these internal predicates are now exposed
through a `SimpleRangeAnalysisInternal` module so it's clear that they
are not for general use.

Author: jbj

cpp/ql/src/experimental/semmle/code/cpp/models/interfaces/SimpleRangeAnalysisExpr.qll

@@ -1,19 +1,39 @@
 /**
+ * EXPERIMENTAL: The API of this module may change without notice.
+ *
  * Provides a class for modeling `Expr`s with a restricted range.
  */
 
 import cpp
+import semmle.code.cpp.rangeanalysis.SimpleRangeAnalysis
 
 /**
- * An expression for which a range can be deduced.
+ * EXPERIMENTAL: The API of this class may change without notice.
+ *
+ * An expression for which a range can be deduced. Extend this class to add
+ * functionality to the range analysis library.
  */
 abstract class SimpleRangeAnalysisExpr extends Expr {
-  /** Gets the lower bound of the expression. */
+  /**
+   * Gets the lower bound of the expression.
+   *
+   * Implementations of this predicate should use
+   * `getFullyConvertedLowerBounds` and `getFullyConvertedUpperBounds` for
+   * recursive calls to get the bounds of their children.
+   */
   abstract float getLowerBounds();
 
-  /** Gets the upper bound of the expression. */
+  /**
+   * Gets the upper bound of the expression.
+   *
+   * Implementations of this predicate should use
+   * `getFullyConvertedLowerBounds` and `getFullyConvertedUpperBounds` for
+   * recursive calls to get the bounds of their children.
+   */
   abstract float getUpperBounds();
 
   /** Holds if this expression depends on the definition `srcDef` for StackVariable `srcVar`. */
   predicate dependsOnDef(RangeSsaDefinition srcDef, StackVariable srcVar) { none() }
 }
+
+import SimpleRangeAnalysisInternal

cpp/ql/src/semmle/code/cpp/rangeanalysis/SimpleRangeAnalysis.qll

@@ -452,13 +452,6 @@ private float addRoundingDownSmall(float x, float small) {
   if (x + small) - x > small then result = (x + small).nextDown() else result = (x + small)
 }
 
-/**
- * Gets the truncated lower bounds of the fully converted expression.
- */
-float getFullyConvertedLowerBounds(Expr expr) {
-  result = getTruncatedLowerBounds(expr.getFullyConverted())
-}
-
 /**
  * Gets the lower bounds of the expression.
  *
@@ -505,13 +498,6 @@ private float getTruncatedLowerBounds(Expr expr) {
     result = exprMinVal(expr)
 }
 
-/**
- * Gets the truncated upper bounds of the fully converted expression.
- */
-float getFullyConvertedUpperBounds(Expr expr) {
-  result = getTruncatedUpperBounds(expr.getFullyConverted())
-}
-
 /**
  * Gets the upper bounds of the expression.
  *
@@ -1527,3 +1513,25 @@ private module SimpleRangeAnalysisCached {
     convertedExprMightOverflowPositively(expr)
   }
 }
+
+/**
+ * INTERNAL: do not use. This module contains utilities for use in the
+ * experimental `SimpleRangeAnalysisExpr` module.
+ */
+module SimpleRangeAnalysisInternal {
+  /**
+   * Gets the truncated lower bounds of the fully converted expression.
+   */
+  float getFullyConvertedLowerBounds(Expr expr) {
+    result = getTruncatedLowerBounds(expr.getFullyConverted())
+  }
+
+  /**
+   * Gets the truncated upper bounds of the fully converted expression.
+   */
+  float getFullyConvertedUpperBounds(Expr expr) {
+    result = getTruncatedUpperBounds(expr.getFullyConverted())
+  }
+}
+
+private import SimpleRangeAnalysisInternal