[ASTMatchers] add three matchers for dependent expressions

Summary:
The new matchers can be used to check if an expression is type-, value- or instantiation-dependent
in a templated context.
These matchers are used in a clang-tidy check and generally useful as the
problem of unresolved templates occurs more often in clang-tidy and they
provide an easy way to check for this issue.

Reviewers: aaron.ballman, alexfh, klimek

Reviewed By: aaron.ballman

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D51880

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@341958 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 40 insertions, 0 deletions

diff --git a/docs/LibASTMatchersReference.html b/docs/LibASTMatchersReference.html
index ae44662489..68a1ab5915 100644
--- a/docs/LibASTMatchersReference.html
+++ b/docs/LibASTMatchersReference.html
@@ -2758,6 +2758,46 @@ enum class Y {};
 </pre></td></tr>
 
 
+<tr><td>Matcher&lt;<a href="http://clang.llvm.org/doxygen/classclang_1_1Expr.html">Expr</a>&gt;</td><td class="name" onclick="toggle('isInstantiationDependent0')"><a name="isInstantiationDependent0Anchor">isInstantiationDependent</a></td><td></td></tr>
+<tr><td colspan="4" class="doc" id="isInstantiationDependent0"><pre>Matches expressions that are instantiation-dependent even if it is
+neither type- nor value-dependent.
+
+In the following example, the expression sizeof(sizeof(T() + T()))
+is instantiation-dependent (since it involves a template parameter T),
+but is neither type- nor value-dependent, since the type of the inner
+sizeof is known (std::size_t) and therefore the size of the outer
+sizeof is known.
+  template&lt;typename T&gt;
+  void f(T x, T y) { sizeof(sizeof(T() + T()); }
+expr(isInstantiationDependent()) matches sizeof(sizeof(T() + T())
+</pre></td></tr>
+
+
+<tr><td>Matcher&lt;<a href="http://clang.llvm.org/doxygen/classclang_1_1Expr.html">Expr</a>&gt;</td><td class="name" onclick="toggle('isTypeDependent0')"><a name="isTypeDependent0Anchor">isTypeDependent</a></td><td></td></tr>
+<tr><td colspan="4" class="doc" id="isTypeDependent0"><pre>Matches expressions that are type-dependent because the template type
+is not yet instantiated.
+
+For example, the expressions "x" and "x + y" are type-dependent in
+the following code, but "y" is not type-dependent:
+  template&lt;typename T&gt;
+  void add(T x, int y) {
+    x + y;
+  }
+expr(isTypeDependent()) matches x + y
+</pre></td></tr>
+
+
+<tr><td>Matcher&lt;<a href="http://clang.llvm.org/doxygen/classclang_1_1Expr.html">Expr</a>&gt;</td><td class="name" onclick="toggle('isValueDependent0')"><a name="isValueDependent0Anchor">isValueDependent</a></td><td></td></tr>
+<tr><td colspan="4" class="doc" id="isValueDependent0"><pre>Matches expression that are value-dependent because they contain a
+non-type template parameter.
+
+For example, the array bound of "Chars" in the following example is
+value-dependent.
+  template&lt;int Size&gt; int f() { return Size; }
+expr(isValueDependent()) matches return Size
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt;<a href="http://clang.llvm.org/doxygen/classclang_1_1FieldDecl.html">FieldDecl</a>&gt;</td><td class="name" onclick="toggle('hasBitWidth0')"><a name="hasBitWidth0Anchor">hasBitWidth</a></td><td>unsigned Width</td></tr>
 <tr><td colspan="4" class="doc" id="hasBitWidth0"><pre>Matches non-static data members that are bit-fields of the specified
 bit width.