C++1y: support 'for', 'while', and 'do ... while' in constant expressions.

llvm-svn: 181181

3 files changed, 71 insertions, 32 deletions

diff --git a/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p3.cpp b/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p3.cpp
index 3bc639dd571..4393727c193 100644
--- a/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p3.cpp
+++ b/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p3.cpp
@@ -143,10 +143,6 @@ constexpr int ForStmt() {
   for (int n = 0; n < 10; ++n)
 #ifndef CXX1Y
   // expected-error@-2 {{statement not allowed in constexpr function}}
-#else
-  // FIXME: Once we support evaluating a for-statement, this diagnostic should disappear.
-  // expected-error@-6 {{never produces a constant expression}}
-  // expected-note@-6 {{subexpression}}
 #endif
     return 0;
 }
@@ -289,9 +285,5 @@ namespace std_example {
 #ifndef CXX1Y
     // expected-error@-5 {{C++1y}}
     // expected-error@-5 {{statement not allowed}}
-#else
-    // FIXME: This should be allowed.
-    // expected-error@-10 {{never produces a constant}}
-    // expected-note@-9 {{subexpression}}
 #endif
 }
diff --git a/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp b/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp
index 820a02a5e03..8a4fa42f002 100644
--- a/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp
+++ b/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp
@@ -87,10 +87,6 @@ struct V {
       /**/;
 #ifndef CXX1Y
     // expected-error@-3 {{statement not allowed in constexpr constructor}}
-#else
-    // FIXME: Once we support evaluating a for-statement, this diagnostic should disappear.
-    // expected-error@-7 {{never produces a constant expression}}
-    // expected-note@-7 {{subexpression}}
 #endif
   }
   constexpr V(int(&)[2]) {
diff --git a/clang/test/SemaCXX/constant-expression-cxx1y.cpp b/clang/test/SemaCXX/constant-expression-cxx1y.cpp
index 2dfded4cc34..d8cfb1c2974 100644
--- a/clang/test/SemaCXX/constant-expression-cxx1y.cpp
+++ b/clang/test/SemaCXX/constant-expression-cxx1y.cpp
@@ -156,33 +156,14 @@ namespace string_assign {
   }
   template<typename Iterator>
   constexpr void reverse(Iterator begin, Iterator end) {
-#if 0 // FIXME: once implementation is complete...
     while (begin != end && begin != --end)
       swap(*begin++, *end);
-#else
-    if (begin != end) {
-      if (begin == --end)
-        return;
-      swap(*begin++, *end);
-      reverse(begin, end);
-    }
-#endif
   }
   template<typename Iterator1, typename Iterator2>
   constexpr bool equal(Iterator1 a, Iterator1 ae, Iterator2 b, Iterator2 be) {
-#if 0 // FIXME: once implementation is complete...
-    while (a != ae && b != be) {
-      if (*a != *b)
-        return false;
-      ++a, ++b;
-    }
-#else
-    if (a != ae && b != be) {
+    while (a != ae && b != be)
       if (*a++ != *b++)
         return false;
-      return equal(a, ae, b, be);
-    }
-#endif
     return a == ae && b == be;
   }
   constexpr bool test1(int n) {
@@ -352,3 +333,73 @@ namespace incdec {
   }
   static_assert(incr(0) == 101, "");
 }
+
+namespace loops {
+  constexpr int fib_loop(int a) {
+    int f_k = 0, f_k_plus_one = 1;
+    for (int k = 1; k != a; ++k) {
+      int f_k_plus_two = f_k + f_k_plus_one;
+      f_k = f_k_plus_one;
+      f_k_plus_one = f_k_plus_two;
+    }
+    return f_k_plus_one;
+  }
+  static_assert(fib_loop(46) == 1836311903, "");
+
+  constexpr bool breaks_work() {
+    int a = 0;
+    for (int n = 0; n != 100; ++n) {
+      ++a;
+      if (a == 5) continue;
+      if ((a % 5) == 0) break;
+    }
+
+    int b = 0;
+    while (b != 17) {
+      ++b;
+      if (b == 6) continue;
+      if ((b % 6) == 0) break;
+    }
+
+    int c = 0;
+    do {
+      ++c;
+      if (c == 7) continue;
+      if ((c % 7) == 0) break;
+    } while (c != 21);
+
+    return a == 10 && b == 12 & c == 14;
+  }
+  static_assert(breaks_work(), "");
+
+  void not_constexpr();
+  constexpr bool no_cont_after_break() {
+    for (;;) {
+      break;
+      not_constexpr();
+    }
+    while (true) {
+      break;
+      not_constexpr();
+    }
+    do {
+      break;
+      not_constexpr();
+    } while (true);
+    return true;
+  }
+  static_assert(no_cont_after_break(), "");
+
+  constexpr bool cond() {
+    for (int a = 1; bool b = a != 3; ++a) {
+      if (!b)
+        return false;
+    }
+    while (bool b = true) {
+      b = false;
+      break;
+    }
+    return true;
+  }
+  static_assert(cond(), "");
+}