Add a narrowing AST matcher that matches on a FunctionDecl with a non-throwing exception specification.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@254516 91177308-0d34-0410-b5e6-96231b3b80d8

docs/LibASTMatchersReference.html

@@ -2236,6 +2236,20 @@ namespaceDecl(isInline()) will match n::m.
 </pre></td></tr>
 
 
+<tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1FunctionDecl.html">FunctionDecl</a>&gt;</td><td class="name" onclick="toggle('isNoThrow0')"><a name="isNoThrow0Anchor">isNoThrow</a></td><td></td></tr>
+<tr><td colspan="4" class="doc" id="isNoThrow0"><pre>Matches functions that have a non-throwing exception specification.
+
+Given:
+  void f();
+  void g() noexcept;
+  void h() throw();
+  void i() throw(int);
+  void j() noexcept(false);
+functionDecl(isNoThrow())
+  matches the declarations of g, and h, but not f, i or j.
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1FunctionDecl.html">FunctionDecl</a>&gt;</td><td class="name" onclick="toggle('isTemplateInstantiation0')"><a name="isTemplateInstantiation0Anchor">isTemplateInstantiation</a></td><td></td></tr>
 <tr><td colspan="4" class="doc" id="isTemplateInstantiation0"><pre>Matches template instantiations of function, class, or static
 member variable template instantiations.

include/clang/ASTMatchers/ASTMatchers.h

@@ -2942,6 +2942,34 @@ AST_MATCHER(FunctionDecl, isDeleted) {
   return Node.isDeleted();
 }
 
+/// \brief Matches functions that have a non-throwing exception specification.
+///
+/// Given:
+/// \code
+///   void f();
+///   void g() noexcept;
+///   void h() throw();
+///   void i() throw(int);
+///   void j() noexcept(false);
+/// \endcode
+/// functionDecl(isNoThrow())
+///   matches the declarations of g, and h, but not f, i or j.
+AST_MATCHER(FunctionDecl, isNoThrow) {
+  const auto *FnTy = Node.getType()->getAs<FunctionProtoType>();
+
+  // If the function does not have a prototype, then it is assumed to be a
+  // throwing function (as it would if the function did not have any exception
+  // specification).
+  if (!FnTy)
+    return false;
+
+  // Assume the best for any unresolved exception specification.
+  if (isUnresolvedExceptionSpec(FnTy->getExceptionSpecType()))
+    return true;
+
+  return FnTy->isNothrow(Node.getASTContext());
+}
+
 /// \brief Matches constexpr variable and function declarations.
 ///
 /// Given:

lib/ASTMatchers/Dynamic/Registry.cpp

@@ -288,6 +288,7 @@ RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(isListInitialization);
   REGISTER_MATCHER(isMemberInitializer);
   REGISTER_MATCHER(isMoveConstructor);
+  REGISTER_MATCHER(isNoThrow);
   REGISTER_MATCHER(isOverride);
   REGISTER_MATCHER(isPrivate);
   REGISTER_MATCHER(isProtected);

unittests/ASTMatchers/ASTMatchersTest.cpp

@@ -1716,6 +1716,15 @@ TEST(IsDeleted, MatchesDeletedFunctionDeclarations) {
                       functionDecl(hasName("Func"), isDeleted())));
 }
 
+TEST(IsNoThrow, MatchesNoThrowFunctionDeclarations) {
+  EXPECT_TRUE(notMatches("void f();", functionDecl(isNoThrow())));
+  EXPECT_TRUE(notMatches("void f() throw(int);", functionDecl(isNoThrow())));
+  EXPECT_TRUE(
+      notMatches("void f() noexcept(false);", functionDecl(isNoThrow())));
+  EXPECT_TRUE(matches("void f() throw();", functionDecl(isNoThrow())));
+  EXPECT_TRUE(matches("void f() noexcept;", functionDecl(isNoThrow())));
+}
+
 TEST(isConstexpr, MatchesConstexprDeclarations) {
   EXPECT_TRUE(matches("constexpr int foo = 42;",
                       varDecl(hasName("foo"), isConstexpr())));