C++: Change API for exposing template parameters.

Matthew Gretton-Dann · Matthew Gretton-Dann · commit 6fe22a76da7d · 2019-11-05T11:39:22.000Z
Note that Declaration::getTemplateArgumentType() and
Declaration::getTemplateArgumentValue() need to be public so that they
can be overriden in derived classes.
diff --git a/cpp/ql/src/semmle/code/cpp/Class.qll b/cpp/ql/src/semmle/code/cpp/Class.qll
@@ -610,7 +610,7 @@ class Class extends UserType {
    * class template. When called on a class template, this will return the
    * `i`th template parameter.
    */
-  override Type getTemplateArgument(int i) {
+  override Type getTemplateArgumentType(int i) {
     class_template_argument(underlyingElement(this), i, unresolveElement(result))
   }
 
@@ -632,7 +632,7 @@ class Class extends UserType {
   }
 
   override predicate involvesTemplateParameter() {
-    getATemplateArgument().involvesTemplateParameter()
+    getATemplateArgument().(Type).involvesTemplateParameter()
   }
 
   /** Holds if this class, struct or union was declared 'final'. */
diff --git a/cpp/ql/src/semmle/code/cpp/Declaration.qll b/cpp/ql/src/semmle/code/cpp/Declaration.qll
@@ -196,33 +196,36 @@ abstract class Declaration extends Locatable, @declaration {
    * When called on a template, this will return a template parameter type for
    * both typed and non-typed parameters.
    */
-  final Type getATemplateArgument() { result = getTemplateArgument(_) }
+  final Locatable getATemplateArgument() { result = getTemplateArgument(_) }
 
   /**
    * Gets a template argument used to instantiate this declaration from a template.
    * When called on a template, this will return a non-typed template
    * parameter value.
    */
-  final Expr getATemplateArgumentValue() { result = getTemplateArgumentValue(_) }
+  final Locatable getATemplateArgumentKind() { result = getTemplateArgumentKind(_) }
 
   /**
    * Gets the `i`th template argument used to instantiate this declaration from a
-   * template. When called on a template, this will return the `i`th template
-   * parameter's type.
+   * template.
    *
    * For example:
    *
    * `template<typename T, T X> class Foo;`
    *
    * Will have `getTemplateArgument(0)` return `T`, and
-   * `getTemplateArgument(1)` return `T`.
+   * `getTemplateArgument(1)` return `X`.
    *
    * `Foo<int, 1> bar;
    *
    * Will have `getTemplateArgument())` return `int`, and
-   * `getTemplateArgument(1)` return `int`.
+   * `getTemplateArgument(1)` return `1`.
    */
-  Type getTemplateArgument(int index) { none() }
+  final Locatable getTemplateArgument(int index) {
+    if exists(getTemplateArgumentValue(index))
+    then result = getTemplateArgumentValue(index)
+    else result = getTemplateArgumentType(index)
+  }
 
   /**
    * Gets the `i`th template argument value used to instantiate this declaration
@@ -233,20 +236,44 @@ abstract class Declaration extends Locatable, @declaration {
    *
    * `template<typename T, T X> class Foo;`
    *
-   * Will have `getTemplateArgumentValue(1)` return `X`, and no result for
-   * `getTemplateArgumentValue(0)`.
+   * Will have `getTemplateArgumentKind(1)` return `T`, and no result for
+   * `getTemplateArgumentKind(0)`.
    *
    * `Foo<int, 10> bar;
    *
-   * Will have `getTemplateArgumentValue(1)` return `10`, and no result for
-   * `getTemplateArgumentValue(0)`.
+   * Will have `getTemplateArgumentKind(1)` return `int`, and no result for
+   * `getTemplateArgumentKind(0)`.
    */
-  Expr getTemplateArgumentValue(int index) { none() }
+  final Locatable getTemplateArgumentKind(int index) {
+    if exists(getTemplateArgumentValue(index))
+    then result = getTemplateArgumentType(index)
+    else none()
+  }
 
   /** Gets the number of template arguments for this declaration. */
   final int getNumberOfTemplateArguments() {
     result = count(int i | exists(getTemplateArgument(i)))
   }
+
+  /**
+   * INTERNAL: Do not use.
+   *
+   * Gets a Type for a template argument.  May be the template argument itself
+   * or the type of a non-type template argument.
+   *
+   * Use `getTemplateArgument` or `getTemplateKind` instead.
+   */
+  Type getTemplateArgumentType(int index) { none() }
+
+  /**
+   * INTERNAL: Do not use.
+   *
+   * Gets an Expression representing the value of a non-type template
+   * argument.
+   *
+   * Use `getTemplateArgument` or `getTemplateKind` instead.
+   */
+  Expr getTemplateArgumentValue(int index) { none() }
 }
 
 /**
diff --git a/cpp/ql/src/semmle/code/cpp/Function.qll b/cpp/ql/src/semmle/code/cpp/Function.qll
@@ -348,7 +348,7 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
    * function template. When called on a function template, this will return the
    * `i`th template parameter.
    */
-  override Type getTemplateArgument(int index) {
+  override Type getTemplateArgumentType(int index) {
     function_template_argument(underlyingElement(this), index, unresolveElement(result))
   }
 
diff --git a/cpp/ql/src/semmle/code/cpp/Print.qll b/cpp/ql/src/semmle/code/cpp/Print.qll
@@ -36,11 +36,11 @@ private string getParameterTypeString(Type parameterType) {
 }
 
 private string getTemplateArgumentString(Declaration d, int i) {
-  if exists(d.getTemplateArgumentValue(i))
+  if exists(d.getTemplateArgumentKind(i))
   then
-    result = d.getTemplateArgument(i).(DumpType).getTypeIdentityString() + " " + d.getTemplateArgumentValue(i)
-  else
-    result = d.getTemplateArgument(i).(DumpType).getTypeIdentityString()
+    result = d.getTemplateArgumentKind(i).(DumpType).getTypeIdentityString() + " " +
+        d.getTemplateArgument(i)
+  else result = d.getTemplateArgument(i).(DumpType).getTypeIdentityString()
 }
 
 /**
diff --git a/cpp/ql/src/semmle/code/cpp/Type.qll b/cpp/ql/src/semmle/code/cpp/Type.qll
@@ -210,7 +210,7 @@ class Type extends Locatable, @type {
     // A function call that provides an explicit template argument that refers to T uses T.
     // We exclude calls within instantiations, since they do not appear directly in the source.
     exists(FunctionCall c |
-      c.getAnExplicitTemplateArgument().refersTo(this) and
+      c.getAnExplicitTemplateArgument().(Type).refersTo(this) and
       result = c and
       not c.getEnclosingFunction().isConstructedFrom(_)
     )
diff --git a/cpp/ql/src/semmle/code/cpp/Variable.qll b/cpp/ql/src/semmle/code/cpp/Variable.qll
@@ -160,7 +160,7 @@ class Variable extends Declaration, @variable {
    * variable template. When called on a variable template, this will return the
    * `i`th template parameter.
    */
-  override Type getTemplateArgument(int index) {
+  override Type getTemplateArgumentType(int index) {
     variable_template_argument(underlyingElement(this), index, unresolveElement(result))
   }
 
diff --git a/cpp/ql/src/semmle/code/cpp/exprs/Call.qll b/cpp/ql/src/semmle/code/cpp/exprs/Call.qll
@@ -139,27 +139,27 @@ class FunctionCall extends Call, @funbindexpr {
   override string getCanonicalQLClass() { result = "FunctionCall" }
 
   /** Gets an explicit template argument for this call. */
-  Type getAnExplicitTemplateArgument() { result = getExplicitTemplateArgument(_) }
+  Locatable getAnExplicitTemplateArgument() { result = getExplicitTemplateArgument(_) }
 
   /** Gets an explicit template argument value for this call. */
-  Expr getAnExplicitTemplateArgumentValue() { result = getExplicitTemplateArgumentValue(_) }
+  Locatable getAnExplicitTemplateArgumentKind() { result = getExplicitTemplateArgumentKind(_) }
 
   /** Gets a template argument for this call. */
-  Type getATemplateArgument() { result = getTarget().getATemplateArgument() }
+  Locatable getATemplateArgument() { result = getTarget().getATemplateArgument() }
 
   /** Gets a template argument value for this call. */
-  Expr getATemplateArgumentValue() { result = getTarget().getATemplateArgumentValue() }
+  Locatable getATemplateArgumentKind() { result = getTarget().getATemplateArgumentKind() }
 
   /** Gets the nth explicit template argument for this call. */
-  Type getExplicitTemplateArgument(int n) {
+  Locatable getExplicitTemplateArgument(int n) {
     n < getNumberOfExplicitTemplateArguments() and
     result = getTemplateArgument(n)
   }
 
   /** Gets the nth explicit template argument value for this call. */
-  Expr getExplicitTemplateArgumentValue(int n) {
+  Locatable getExplicitTemplateArgumentKind(int n) {
     n < getNumberOfExplicitTemplateArguments() and
-    result = getTemplateArgumentValue(n)
+    result = getTemplateArgumentKind(n)
   }
 
   /** Gets the number of explicit template arguments for this call. */
@@ -172,14 +172,11 @@ class FunctionCall extends Call, @funbindexpr {
   /** Gets the number of template arguments for this call. */
   int getNumberOfTemplateArguments() { result = count(int i | exists(getTemplateArgument(i))) }
 
-  /** Gets the number of template argument which are values for this call. */
-  int getNumberOfTemplateArgumentValues() { result = count(int i | exists(getTemplateArgumentValue(i))) }
-
   /** Gets the nth template argument for this call (indexed from 0). */
-  Type getTemplateArgument(int n) { result = getTarget().getTemplateArgument(n) }
+  Locatable getTemplateArgument(int n) { result = getTarget().getTemplateArgument(n) }
 
   /** Gets the nth template argument value for this call (indexed from 0). */
-  Expr getTemplateArgumentValue(int n) { result = getTarget().getTemplateArgumentValue(n) }
+  Locatable getTemplateArgumentKind(int n) { result = getTarget().getTemplateArgumentKind(n) }
 
   /** Holds if any template arguments for this call are implicit / deduced. */
   predicate hasImplicitTemplateArguments() {
diff --git a/cpp/ql/test/library-tests/templates/CPP-202/template_args.expected b/cpp/ql/test/library-tests/templates/CPP-202/template_args.expected
@@ -1,6 +1,6 @@
 | file://:0:0:0:0 | __va_list_tag | <none> |
-| test.cpp:3:8:3:9 | s1<<expression>> | bool |
-| test.cpp:3:8:3:9 | s1<<unnamed>> | bool |
+| test.cpp:3:8:3:9 | s1<<expression>> | {...} |
+| test.cpp:3:8:3:9 | s1<<unnamed>> | (null) |
 | test.cpp:5:8:5:9 | s2<T> | T |
 | test.cpp:5:8:5:9 | s2<T> | T |
 | test.cpp:7:8:7:9 | s3<T, <unnamed>> | (unnamed) |
diff --git a/cpp/ql/test/library-tests/templates/nontype_instantiations/classes/test.ql b/cpp/ql/test/library-tests/templates/nontype_instantiations/classes/test.ql
@@ -1,4 +1,4 @@
 import cpp
 
 from Class c
-select c, c.getATemplateArgument(), c.getATemplateArgumentValue()
+select c, c.getATemplateArgumentKind(), c.getATemplateArgument()
diff --git a/cpp/ql/test/library-tests/templates/nontype_instantiations/functions/test.ql b/cpp/ql/test/library-tests/templates/nontype_instantiations/functions/test.ql
@@ -1,4 +1,4 @@
 import cpp
 
 from Function f
-select f, f.getATemplateArgument(), f.getATemplateArgumentValue()
+select f, f.getATemplateArgumentKind(), f.getATemplateArgument()
diff --git a/cpp/ql/test/library-tests/templates/nontype_instantiations/general/test.expected b/cpp/ql/test/library-tests/templates/nontype_instantiations/general/test.expected
@@ -1,10 +1,13 @@
-| test.cpp:3:8:3:8 | C<1> | file://:0:0:0:0 | int | test.cpp:5:25:5:25 | 1 |
-| test.cpp:3:8:3:8 | C<2> | file://:0:0:0:0 | int | file://:0:0:0:0 | 2 |
-| test.cpp:3:8:3:8 | C<x> | file://:0:0:0:0 | int | file://:0:0:0:0 | x |
-| test.cpp:10:8:10:8 | D<T, X> | test.cpp:9:19:9:19 | T | file://:0:0:0:0 | X |
-| test.cpp:10:8:10:8 | D<int, 2> | file://:0:0:0:0 | int | test.cpp:12:8:12:8 | 2 |
-| test.cpp:10:8:10:8 | D<long, 2L> | file://:0:0:0:0 | long | file://:0:0:0:0 | 2 |
-| test.cpp:16:8:16:8 | E<T, X> | file://:0:0:0:0 | T * | file://:0:0:0:0 | X |
-| test.cpp:16:8:16:8 | E<T, X> | test.cpp:15:19:15:19 | T | file://:0:0:0:0 | X |
-| test.cpp:16:8:16:8 | E<int, (int *)nullptr> | file://:0:0:0:0 | int | file://:0:0:0:0 | 0 |
-| test.cpp:16:8:16:8 | E<int, (int *)nullptr> | file://:0:0:0:0 | int * | file://:0:0:0:0 | 0 |
+| test.cpp:3:8:3:8 | C<1> | 0 | int | test.cpp:5:25:5:25 | 1 |
+| test.cpp:3:8:3:8 | C<2> | 0 | int | file://:0:0:0:0 | 2 |
+| test.cpp:3:8:3:8 | C<x> | 0 | int | file://:0:0:0:0 | x |
+| test.cpp:10:8:10:8 | D<T, X> | 0 | <none> | test.cpp:9:19:9:19 | T |
+| test.cpp:10:8:10:8 | D<T, X> | 1 | T | file://:0:0:0:0 | X |
+| test.cpp:10:8:10:8 | D<int, 2> | 0 | <none> | file://:0:0:0:0 | int |
+| test.cpp:10:8:10:8 | D<int, 2> | 1 | int | test.cpp:12:8:12:8 | 2 |
+| test.cpp:10:8:10:8 | D<long, 2L> | 0 | <none> | file://:0:0:0:0 | long |
+| test.cpp:10:8:10:8 | D<long, 2L> | 1 | long | file://:0:0:0:0 | 2 |
+| test.cpp:16:8:16:8 | E<T, X> | 0 | <none> | test.cpp:15:19:15:19 | T |
+| test.cpp:16:8:16:8 | E<T, X> | 1 | T * | file://:0:0:0:0 | X |
+| test.cpp:16:8:16:8 | E<int, (int *)nullptr> | 0 | <none> | file://:0:0:0:0 | int |
+| test.cpp:16:8:16:8 | E<int, (int *)nullptr> | 1 | int * | file://:0:0:0:0 | 0 |
diff --git a/cpp/ql/test/library-tests/templates/nontype_instantiations/general/test.ql b/cpp/ql/test/library-tests/templates/nontype_instantiations/general/test.ql
@@ -1,4 +1,14 @@
 import cpp
 
-from Declaration d
-select d, d.getATemplateArgument(), d.getATemplateArgumentValue()
+string maybeGetTemplateArgumentKind(Declaration d, int i) {
+  (
+    if exists(d.getTemplateArgumentKind(i))
+    then result = d.getTemplateArgumentKind(i).toString()
+    else result = "<none>"
+  ) and
+  i = [0 .. d.getNumberOfTemplateArguments()]
+}
+
+from Declaration d, int i
+where i >= 0 and i < d.getNumberOfTemplateArguments()
+select d, i, maybeGetTemplateArgumentKind(d, i), d.getTemplateArgument(i)

Original file line number	Diff line number	Diff line change
`@@ -610,7 +610,7 @@ class Class extends UserType {`
`610`	`610`	`* class template. When called on a class template, this will return the`
`611`	`611`	* `i`th template parameter.
`612`	`612`	`*/`
`613`		`- override Type getTemplateArgument(int i) {`
	`613`	`+ override Type getTemplateArgumentType(int i) {`
`614`	`614`	`class_template_argument(underlyingElement(this), i, unresolveElement(result))`
`615`	`615`	`}`
`616`	`616`
`@@ -632,7 +632,7 @@ class Class extends UserType {`
`632`	`632`	`}`
`633`	`633`
`634`	`634`	`override predicate involvesTemplateParameter() {`
`635`		`- getATemplateArgument().involvesTemplateParameter()`
	`635`	`+ getATemplateArgument().(Type).involvesTemplateParameter()`
`636`	`636`	`}`
`637`	`637`
`638`	`638`	`/** Holds if this class, struct or union was declared 'final'. */`
Original file line number	Diff line number	Diff line change
`@@ -348,7 +348,7 @@ class Function extends Declaration, ControlFlowNode, AccessHolder, @function {`
`348`	`348`	`* function template. When called on a function template, this will return the`
`349`	`349`	* `i`th template parameter.
`350`	`350`	`*/`
`351`		`- override Type getTemplateArgument(int index) {`
	`351`	`+ override Type getTemplateArgumentType(int index) {`
`352`	`352`	`function_template_argument(underlyingElement(this), index, unresolveElement(result))`
`353`	`353`	`}`
`354`	`354`
Original file line number	Diff line number	Diff line change
`@@ -36,11 +36,11 @@ private string getParameterTypeString(Type parameterType) {`
`36`	`36`	`}`
`37`	`37`
`38`	`38`	`private string getTemplateArgumentString(Declaration d, int i) {`
`39`		`- if exists(d.getTemplateArgumentValue(i))`
	`39`	`+ if exists(d.getTemplateArgumentKind(i))`
`40`	`40`	`then`
`41`		`- result = d.getTemplateArgument(i).(DumpType).getTypeIdentityString() + " " + d.getTemplateArgumentValue(i)`
`42`		`- else`
`43`		`- result = d.getTemplateArgument(i).(DumpType).getTypeIdentityString()`
	`41`	`+ result = d.getTemplateArgumentKind(i).(DumpType).getTypeIdentityString() + " " +`
	`42`	`+ d.getTemplateArgument(i)`
	`43`	`+ else result = d.getTemplateArgument(i).(DumpType).getTypeIdentityString()`
`44`	`44`	`}`
`45`	`45`
`46`	`46`	`/**`
Original file line number	Diff line number	Diff line change
`@@ -210,7 +210,7 @@ class Type extends Locatable, @type {`
`210`	`210`	`// A function call that provides an explicit template argument that refers to T uses T.`
`211`	`211`	`// We exclude calls within instantiations, since they do not appear directly in the source.`
`212`	`212`	`exists(FunctionCall c \|`
`213`		`- c.getAnExplicitTemplateArgument().refersTo(this) and`
	`213`	`+ c.getAnExplicitTemplateArgument().(Type).refersTo(this) and`
`214`	`214`	`result = c and`
`215`	`215`	`not c.getEnclosingFunction().isConstructedFrom(_)`
`216`	`216`	`)`
Original file line number	Diff line number	Diff line change
`@@ -160,7 +160,7 @@ class Variable extends Declaration, @variable {`
`160`	`160`	`* variable template. When called on a variable template, this will return the`
`161`	`161`	* `i`th template parameter.
`162`	`162`	`*/`
`163`		`- override Type getTemplateArgument(int index) {`
	`163`	`+ override Type getTemplateArgumentType(int index) {`
`164`	`164`	`variable_template_argument(underlyingElement(this), index, unresolveElement(result))`
`165`	`165`	`}`
`166`	`166`