github · smowton · Mar 11, 2022 · Mar 8, 2022 · Mar 9, 2022 · Mar 9, 2022
@@ -0,0 +1,6 @@
+---
+category: minorAnalysis
+---
+ * Add new predicate `CompileTimeConstantExpr.getStringifiedValue` which attempts to compute the
+   `String.valueOf` string rendering of a constant expression. This predicate is now used to 
+   compute the string value of an `AddExpr` that has the type `String`.
@@ -161,18 +161,50 @@ class CompileTimeConstantExpr extends Expr {
     )
   }
 
+  /**
+   * Gets the stringified value of this expression, where possible.
+   *
+   * The stringified version of a compile-time constant expression is the equivalent to
+   * the result of calling `String.valueOf(expr)` on the expression.
+   *
+   * Note that this does not handle the following cases:
+   *
+   * - mathematical computations of type `long`, `float`, or `double`.
+   */
+  pragma[nomagic]
+  string getStringifiedValue() {
+    result = this.getStringValue()
+    or
+    result = this.(Literal).getValue()
+    or
+    result = this.getBooleanValue().toString()
+    or
+    result = this.getIntValue().toString()
+    or
+    // Ternary conditional, with compile-time constant condition.
+    exists(ConditionalExpr ce, boolean condition |
+      ce = this and
+      condition = ce.getCondition().(CompileTimeConstantExpr).getBooleanValue() and
+      result = ce.getBranchExpr(condition).(CompileTimeConstantExpr).getStringifiedValue()
+    )
+    or
+    exists(Variable v | this = v.getAnAccess() |
+      result = v.getInitializer().(CompileTimeConstantExpr).getStringifiedValue()
+    )
+  }
+
   /**
    * Gets the string value of this expression, where possible.
    */
   pragma[nomagic]
   string getStringValue() {
     result = this.(StringLiteral).getValue()
     or
-    result = this.(CharacterLiteral).getValue()
-    or
+    this.getType() instanceof TypeString and // When the expression type is `String`
     result =
-      this.(AddExpr).getLeftOperand().(CompileTimeConstantExpr).getStringValue() +
-        this.(AddExpr).getRightOperand().(CompileTimeConstantExpr).getStringValue()
+      // Then the resultant string is the addition of both operands stringified value, regardless of type.
+      this.(AddExpr).getLeftOperand().(CompileTimeConstantExpr).getStringifiedValue() +
+        this.(AddExpr).getRightOperand().(CompileTimeConstantExpr).getStringifiedValue()
     or
     // Ternary conditional, with compile-time constant condition.
     exists(ConditionalExpr ce, boolean condition |

@@ -1,4 +1,4 @@
-import semmle.code.java.Expr
+import java
 
 from CompileTimeConstantExpr constant, RefType tpe
 where

@@ -133,6 +133,151 @@ constants/Initializers.java:
 #   37|         0: [AssignExpr] ...=...
 #   37|           0: [VarAccess] f
 #   37|           1: [IntegerLiteral] 42
+constants/Stringified.java:
+#    0| [CompilationUnit] Stringified
+#    3|   1: [Class] Stringified
+#    4|     2: [Method] stringified
+#    4|       3: [TypeAccess] void
+#-----|       4: (Parameters)
+#    4|         0: [Parameter] notConstant
+#    4|           0: [TypeAccess] String
+#    4|       5: [BlockStmt] { ... }
+#    5|         0: [LocalVariableDeclStmt] var ...;
+#    5|           0: [TypeAccess] String
+#    5|           1: [LocalVariableDeclExpr] withNotConstant
+#    5|             0: [AddExpr] ... + ...
+#    5|               0: [StringLiteral] "a"
+#    5|               1: [VarAccess] notConstant
+#    6|         1: [LocalVariableDeclStmt] var ...;
+#    6|           0: [TypeAccess] String
+#    6|           1: [LocalVariableDeclExpr] string
+#    6|             0: [StringLiteral] "a" + "b"
+#    7|         2: [LocalVariableDeclStmt] var ...;
+#    7|           0: [TypeAccess] String
+#    7|           1: [LocalVariableDeclExpr] stringWithChar
+#    7|             0: [AddExpr] ... + ...
+#    7|               0: [StringLiteral] "ab"
+#    7|               1: [CharacterLiteral] 'c'
+#    8|         3: [LocalVariableDeclStmt] var ...;
+#    8|           0: [TypeAccess] String
+#    8|           1: [LocalVariableDeclExpr] stringWithBool
+#    8|             0: [AddExpr] ... + ...
+#    8|               0: [StringLiteral] "ab"
+#    8|               1: [BooleanLiteral] true
+#    9|         4: [LocalVariableDeclStmt] var ...;
+#    9|           0: [TypeAccess] String
+#    9|           1: [LocalVariableDeclExpr] stringWithInt
+#    9|             0: [AddExpr] ... + ...
+#    9|               0: [StringLiteral] "ab"
+#    9|               1: [IntegerLiteral] 42
+#   10|         5: [LocalVariableDeclStmt] var ...;
+#   10|           0: [TypeAccess] String
+#   10|           1: [LocalVariableDeclExpr] stringWithDouble
+#   10|             0: [AddExpr] ... + ...
+#   10|               0: [StringLiteral] "ab"
+#   10|               1: [DoubleLiteral] 43.0
+#   11|         6: [LocalVariableDeclStmt] var ...;
+#   11|           0: [TypeAccess] String
+#   11|           1: [LocalVariableDeclExpr] stringWithFloat
+#   11|             0: [AddExpr] ... + ...
+#   11|               0: [StringLiteral] "ab"
+#   11|               1: [FloatingPointLiteral] 44.0f
+#   12|         7: [LocalVariableDeclStmt] var ...;
+#   12|           0: [TypeAccess] String
+#   12|           1: [LocalVariableDeclExpr] stringWithLong
+#   12|             0: [AddExpr] ... + ...
+#   12|               0: [StringLiteral] "ab"
+#   12|               1: [LongLiteral] 45L
+#   13|         8: [LocalVariableDeclStmt] var ...;
+#   13|           0: [TypeAccess] String
+#   13|           1: [LocalVariableDeclExpr] stringWithShort
+#   13|             0: [AddExpr] ... + ...
+#   13|               0: [StringLiteral] "ab"
+#   13|               1: [CastExpr] (...)...
+#   13|                 0: [TypeAccess] short
+#   13|                 1: [IntegerLiteral] 46
+#   14|         9: [LocalVariableDeclStmt] var ...;
+#   14|           0: [TypeAccess] String
+#   14|           1: [LocalVariableDeclExpr] stringWithByte
+#   14|             0: [AddExpr] ... + ...
+#   14|               0: [StringLiteral] "ab"
+#   14|               1: [CastExpr] (...)...
+#   14|                 0: [TypeAccess] byte
+#   14|                 1: [IntegerLiteral] 47
+#   15|         10: [LocalVariableDeclStmt] var ...;
+#   15|           0: [TypeAccess] String
+#   15|           1: [LocalVariableDeclExpr] charWithString
+#   15|             0: [AddExpr] ... + ...
+#   15|               0: [CharacterLiteral] 'a'
+#   15|               1: [StringLiteral] "bc"
+#   16|         11: [LocalVariableDeclStmt] var ...;
+#   16|           0: [TypeAccess] String
+#   16|           1: [LocalVariableDeclExpr] boolWithString
+#   16|             0: [AddExpr] ... + ...
+#   16|               0: [BooleanLiteral] true
+#   16|               1: [StringLiteral] "bc"
+#   17|         12: [LocalVariableDeclStmt] var ...;
+#   17|           0: [TypeAccess] String
+#   17|           1: [LocalVariableDeclExpr] intWithString
+#   17|             0: [AddExpr] ... + ...
+#   17|               0: [IntegerLiteral] 42
+#   17|               1: [StringLiteral] "bc"
+#   18|         13: [LocalVariableDeclStmt] var ...;
+#   18|           0: [TypeAccess] String
+#   18|           1: [LocalVariableDeclExpr] doubleWithString
+#   18|             0: [AddExpr] ... + ...
+#   18|               0: [DoubleLiteral] 43.0
+#   18|               1: [StringLiteral] "bc"
+#   19|         14: [LocalVariableDeclStmt] var ...;
+#   19|           0: [TypeAccess] String
+#   19|           1: [LocalVariableDeclExpr] floatWithString
+#   19|             0: [AddExpr] ... + ...
+#   19|               0: [FloatingPointLiteral] 44.0f
+#   19|               1: [StringLiteral] "bc"
+#   20|         15: [LocalVariableDeclStmt] var ...;
+#   20|           0: [TypeAccess] String
+#   20|           1: [LocalVariableDeclExpr] longWithString
+#   20|             0: [AddExpr] ... + ...
+#   20|               0: [LongLiteral] 45L
+#   20|               1: [StringLiteral] "bc"
+#   21|         16: [LocalVariableDeclStmt] var ...;
+#   21|           0: [TypeAccess] String
+#   21|           1: [LocalVariableDeclExpr] shortWithString
+#   21|             0: [AddExpr] ... + ...
+#   21|               0: [CastExpr] (...)...
+#   21|                 0: [TypeAccess] short
+#   21|                 1: [IntegerLiteral] 46
+#   21|               1: [StringLiteral] "bc"
+#   22|         17: [LocalVariableDeclStmt] var ...;
+#   22|           0: [TypeAccess] String
+#   22|           1: [LocalVariableDeclExpr] byteWithString
+#   22|             0: [AddExpr] ... + ...
+#   22|               0: [CastExpr] (...)...
+#   22|                 0: [TypeAccess] byte
+#   22|                 1: [IntegerLiteral] 47
+#   22|               1: [StringLiteral] "bc"
+#   24|         18: [LocalVariableDeclStmt] var ...;
+#   24|           0: [TypeAccess] String
+#   24|           1: [LocalVariableDeclExpr] stringWithExponent
+#   24|             0: [AddExpr] ... + ...
+#   24|               0: [StringLiteral] "a"
+#   24|               1: [DoubleLiteral] 10e1
+#   25|         19: [LocalVariableDeclStmt] var ...;
+#   25|           0: [TypeAccess] String
+#   25|           1: [LocalVariableDeclExpr] stringWithBooleanOr
+#   25|             0: [AddExpr] ... + ...
+#   25|               0: [StringLiteral] "a"
+#   25|               1: [OrLogicalExpr] ... || ...
+#   25|                 0: [BooleanLiteral] true
+#   25|                 1: [BooleanLiteral] false
+#   26|         20: [LocalVariableDeclStmt] var ...;
+#   26|           0: [TypeAccess] String
+#   26|           1: [LocalVariableDeclExpr] stringWithIntDivide
+#   26|             0: [AddExpr] ... + ...
+#   26|               0: [StringLiteral] "a"
+#   26|               1: [DivExpr] ... / ...
+#   26|                 0: [IntegerLiteral] 168
+#   26|                 1: [IntegerLiteral] 4
 constants/Values.java:
 #    0| [CompilationUnit] Values
 #    4|   1: [Class] Values
@@ -526,3 +671,9 @@ constants/Values.java:
 #   92|             0: [AddExpr] ... + ...
 #   92|               0: [StringLiteral] "ab"
 #   92|               1: [CharacterLiteral] 'c'
+#   94|         70: [LocalVariableDeclStmt] var ...;
+#   94|           0: [TypeAccess] int
+#   94|           1: [LocalVariableDeclExpr] charWithChar
+#   94|             0: [AddExpr] ... + ...
+#   94|               0: [CharacterLiteral] 'a'
+#   94|               1: [CharacterLiteral] 'b'
@@ -0,0 +1,28 @@
+package constants;
+
+public class Stringified {
+    void stringified(final String notConstant) {
+        String withNotConstant = "a" + notConstant;
+        String string = "a" + "b"; //ab
+        String stringWithChar = "ab" + 'c'; //abc
+        String stringWithBool = "ab" + true; //abtrue
+        String stringWithInt = "ab" + 42; //ab42
+        String stringWithDouble = "ab" + 43.0; //ab43.0
+        String stringWithFloat = "ab" + 44.0f; //ab44.0
+        String stringWithLong = "ab" + 45L; //ab45
+        String stringWithShort = "ab" + (short) 46; //ab46
+        String stringWithByte = "ab" + (byte) 47; //ab47
+        String charWithString = 'a' + "bc"; //abc
+        String boolWithString = true + "bc"; //truebc
+        String intWithString = 42 + "bc"; //42bc
+        String doubleWithString = 43.0 + "bc"; //43.0bc
+        String floatWithString = 44.0f + "bc"; //44.0bc
+        String longWithString = 45L + "bc"; //45bc
+        String shortWithString = (short) 46 + "bc"; //46bc
+        String byteWithString = (byte) 47 + "bc"; //47bc
+
+        String stringWithExponent = "a" + 10e1; //a100
+        String stringWithBooleanOr = "a" + (true || false); //atrue
+        String stringWithIntDivide = "a" + (168 / 4); //a42
+    }
+}
@@ -90,5 +90,7 @@ void values(final int notConstant) {
         int var_nonfinald_local = var_field; //Not constant
         String concatenatedString = "a" + "b"; //ab
         String concatenatedChar = "ab" + 'c'; //abc
+
+        int charWithChar = 'a' + 'b'; //195
     }
 }
@@ -1,4 +1,4 @@
-import semmle.code.java.Variable
+import java
 
 from Variable v, CompileTimeConstantExpr init, RefType enclosing, boolean constant
 where

@@ -1,4 +1,4 @@
-import semmle.code.java.Variable
+import java
 
 from Variable v, Expr init, RefType enclosing
 where

@@ -37,3 +37,4 @@
 | constants/Values.java:86:25:86:35 | final_field | 42 |
 | constants/Values.java:87:33:87:34 | 42 | 42 |
 | constants/Values.java:88:25:88:35 | final_local | 42 |
+| constants/Values.java:94:28:94:36 | ... + ... | 195 |
@@ -1,9 +1,9 @@
-import semmle.code.java.Variable
+import java
 
 from Variable v, CompileTimeConstantExpr init, RefType enclosing, int constant
 where
   v.getInitializer() = init and
   init.getEnclosingCallable().getDeclaringType() = enclosing and
-  enclosing.hasQualifiedName("constants", "Values") and
+  enclosing.hasQualifiedName("constants", ["Values", "Stringified"]) and
   constant = init.getIntValue()
 select init, constant
@@ -1,3 +1,25 @@
-| constants/Values.java:19:29:19:31 | '*' | * |
+| constants/Stringified.java:6:25:6:33 | "a" + "b" | ab |
+| constants/Stringified.java:7:33:7:42 | ... + ... | ab99 |
+| constants/Stringified.java:7:33:7:42 | ... + ... | abc |
+| constants/Stringified.java:8:33:8:43 | ... + ... | abtrue |
+| constants/Stringified.java:9:32:9:40 | ... + ... | ab42 |
+| constants/Stringified.java:10:35:10:45 | ... + ... | ab43.0 |
+| constants/Stringified.java:11:34:11:45 | ... + ... | ab44.0 |
+| constants/Stringified.java:12:33:12:42 | ... + ... | ab45 |
+| constants/Stringified.java:13:34:13:50 | ... + ... | ab46 |
+| constants/Stringified.java:14:33:14:48 | ... + ... | ab47 |
+| constants/Stringified.java:15:33:15:42 | ... + ... | 97bc |
+| constants/Stringified.java:15:33:15:42 | ... + ... | abc |
+| constants/Stringified.java:16:33:16:43 | ... + ... | truebc |
+| constants/Stringified.java:17:32:17:40 | ... + ... | 42bc |
+| constants/Stringified.java:18:35:18:45 | ... + ... | 43.0bc |
+| constants/Stringified.java:19:34:19:45 | ... + ... | 44.0bc |
+| constants/Stringified.java:20:33:20:42 | ... + ... | 45bc |
+| constants/Stringified.java:21:34:21:50 | ... + ... | 46bc |
+| constants/Stringified.java:22:33:22:48 | ... + ... | 47bc |
+| constants/Stringified.java:24:37:24:46 | ... + ... | a100.0 |
+| constants/Stringified.java:25:38:25:58 | ... + ... | atrue |
+| constants/Stringified.java:26:38:26:52 | ... + ... | a42 |
 | constants/Values.java:91:37:91:45 | "a" + "b" | ab |
+| constants/Values.java:92:35:92:44 | ... + ... | ab99 |
 | constants/Values.java:92:35:92:44 | ... + ... | abc |
@@ -1,9 +1,9 @@
-import semmle.code.java.Variable
+import java
 
 from Variable v, CompileTimeConstantExpr init, RefType enclosing, string constant
 where
   v.getInitializer() = init and
   init.getEnclosingCallable().getDeclaringType() = enclosing and
-  enclosing.hasQualifiedName("constants", "Values") and
+  enclosing.hasQualifiedName("constants", ["Values", "Stringified"]) and
   constant = init.getStringValue()
 select init, constant