Exclude bool literals and char literals instead of types

Bool literals do not always have a bool type so we exclude them
using the bool literal class.
We exclude using the char literal class to reduce duplication
and increase coverage in case of new char literals.

Author: rvermeulen

cpp/common/src/codingstandards/cpp/Literals.qll

@@ -3,6 +3,7 @@
  */
 
 import cpp
+import codingstandards.cpp.Cpp14Literal
 
 /** Gets `Literal.getValueText()` truncated to at most 20 characters. */
 string getTruncatedLiteralText(Literal l) {
@@ -36,10 +37,12 @@ class Utf32StringLiteral extends StringLiteral {
 class CompileTimeComputedIntegralLiteral extends Literal {
   CompileTimeComputedIntegralLiteral() {
     this.getUnspecifiedType() instanceof IntegralType and
-    not this.getUnspecifiedType() instanceof BoolType and
-    not this.getUnspecifiedType() instanceof CharType and
-    // In some cases we still type char constants like '.' as int
-    not this.getValueText().trim().matches("'%'") and
+    // Exclude bool, whose value text is true or false, but the value itself
+    // is 1 or 0.
+    not this instanceof BoolLiteral and 
+    // Exclude character literals, whose value text is the quoted character, but the value
+    // is the numeric value of the character.
+    not this instanceof Cpp14Literal::CharLiteral and
     not this.getValueText()
         .trim()
         .regexpMatch("([0-9][0-9']*|0[xX][0-9a-fA-F']+|0b[01']+)[uU]?([lL]{1,2}|[zZ])?") and