Move major version suffix regex into one place

Author: owen-mc

go/ql/lib/semmle/go/Packages.qll

@@ -23,7 +23,7 @@ class Package extends @package {
    * removed.
    */
   string getPathWithoutMajorVersionSuffix() {
-    result = this.getPath().regexpReplaceAll("[./]v\\d+", "")
+    result = this.getPath().regexpReplaceAll(majorVersionSuffixRegex(), "")
   }
 
   /** Gets the scope of this package. */
@@ -33,6 +33,8 @@ class Package extends @package {
   string toString() { result = "package " + this.getPath() }
 }
 
+string majorVersionSuffixRegex() { result = "[./]v\\d+" }
+
 /**
  * Gets an import path that identifies a package in module `mod` with the given path,
  * possibly modulo [semantic import versioning](https://github.com/golang/go/wiki/Modules#semantic-import-versioning).

go/ql/lib/semmle/go/dataflow/ExternalFlow.qll

@@ -322,16 +322,15 @@ private predicate elementSpec(
  */
 bindingset[p]
 private string interpretPackage(string p) {
-  exists(Package pkg, string thisVersion, string specifiedVersionRegex |
+  exists(Package pkg, string thisVersion |
     result = pkg.getPath() and
-    thisVersion = "$THISVERSION" and
-    specifiedVersionRegex = "[./]v\\d+"
+    thisVersion = "$THISVERSION"
   |
     p = result + thisVersion
     or
     not p = any(string s) + thisVersion and
     (
-      if exists(p.regexpFind(specifiedVersionRegex, 0, _))
+      if exists(p.regexpFind(majorVersionSuffixRegex(), 0, _))
       then result = p
       else p = pkg.getPathWithoutMajorVersionSuffix()
     )