1abea951c34876a5374d0e3678c7989b225c5c895Anders Carlsson// RUN: %clang_cc1 -fcxx-exceptions -fexceptions -fsyntax-only -verify %s
254dabfca850ca9e60e9ffb60003529f868d4d127Douglas Gregortemplate<typename T, typename U>
354dabfca850ca9e60e9ffb60003529f868d4d127Douglas Gregorstruct X0 {
454dabfca850ca9e60e9ffb60003529f868d4d127Douglas Gregor  void f(T x, U y) {
5d7e2705961bacb9df5d9119403c01c9b04aff97fDouglas Gregor    (void)(x + y); // expected-error{{invalid operands}}
654dabfca850ca9e60e9ffb60003529f868d4d127Douglas Gregor  }
754dabfca850ca9e60e9ffb60003529f868d4d127Douglas Gregor};
854dabfca850ca9e60e9ffb60003529f868d4d127Douglas Gregor
954dabfca850ca9e60e9ffb60003529f868d4d127Douglas Gregorstruct X1 { };
1054dabfca850ca9e60e9ffb60003529f868d4d127Douglas Gregor
1154dabfca850ca9e60e9ffb60003529f868d4d127Douglas Gregortemplate struct X0<int, float>;
1254dabfca850ca9e60e9ffb60003529f868d4d127Douglas Gregortemplate struct X0<int*, int>;
1354dabfca850ca9e60e9ffb60003529f868d4d127Douglas Gregortemplate struct X0<int X1::*, int>; // expected-note{{instantiation of}}
14e7a18c88b77523cf1085d239fd373770ba5791f1Douglas Gregor
15e7a18c88b77523cf1085d239fd373770ba5791f1Douglas Gregortemplate<typename T>
16e7a18c88b77523cf1085d239fd373770ba5791f1Douglas Gregorstruct X2 {
17e7a18c88b77523cf1085d239fd373770ba5791f1Douglas Gregor  void f(T);
18e7a18c88b77523cf1085d239fd373770ba5791f1Douglas Gregor
19e7a18c88b77523cf1085d239fd373770ba5791f1Douglas Gregor  T g(T x, T y) {
20b9f1b8d877541e76390cd3807c2dcff2f950360aDouglas Gregor    /* DeclStmt */;
21b9f1b8d877541e76390cd3807c2dcff2f950360aDouglas Gregor    T *xp = &x, &yr = y; // expected-error{{pointer to a reference}}
22e7a18c88b77523cf1085d239fd373770ba5791f1Douglas Gregor    /* NullStmt */;
23e7a18c88b77523cf1085d239fd373770ba5791f1Douglas Gregor  }
24e7a18c88b77523cf1085d239fd373770ba5791f1Douglas Gregor};
25e7a18c88b77523cf1085d239fd373770ba5791f1Douglas Gregor
26e7a18c88b77523cf1085d239fd373770ba5791f1Douglas Gregortemplate struct X2<int>;
27b9f1b8d877541e76390cd3807c2dcff2f950360aDouglas Gregortemplate struct X2<int&>; // expected-note{{instantiation of}}
28137fa562caedf11df4bb10f2657651a785769ca7Anders Carlsson
29137fa562caedf11df4bb10f2657651a785769ca7Anders Carlssontemplate<typename T>
30137fa562caedf11df4bb10f2657651a785769ca7Anders Carlssonstruct X3 {
31137fa562caedf11df4bb10f2657651a785769ca7Anders Carlsson  void f(T) {
32137fa562caedf11df4bb10f2657651a785769ca7Anders Carlsson    Label:
33137fa562caedf11df4bb10f2657651a785769ca7Anders Carlsson    T x;
34137fa562caedf11df4bb10f2657651a785769ca7Anders Carlsson    goto Label;
35137fa562caedf11df4bb10f2657651a785769ca7Anders Carlsson  }
36137fa562caedf11df4bb10f2657651a785769ca7Anders Carlsson};
37137fa562caedf11df4bb10f2657651a785769ca7Anders Carlsson
38137fa562caedf11df4bb10f2657651a785769ca7Anders Carlssontemplate struct X3<int>;
3903d77760a5db7990724b6901cea958a673ce0b39Anders Carlsson
4003d77760a5db7990724b6901cea958a673ce0b39Anders Carlssontemplate <typename T> struct X4 {
4103d77760a5db7990724b6901cea958a673ce0b39Anders Carlsson  T f() const {
42184aa4e6ded190bfb3bbe207040467f8d7e28a04Chris Lattner    return; // expected-error{{non-void function 'f' should return a value}}
4303d77760a5db7990724b6901cea958a673ce0b39Anders Carlsson  }
4403d77760a5db7990724b6901cea958a673ce0b39Anders Carlsson
4503d77760a5db7990724b6901cea958a673ce0b39Anders Carlsson  T g() const {
46184aa4e6ded190bfb3bbe207040467f8d7e28a04Chris Lattner    return 1; // expected-error{{void function 'g' should not return a value}}
4703d77760a5db7990724b6901cea958a673ce0b39Anders Carlsson  }
4803d77760a5db7990724b6901cea958a673ce0b39Anders Carlsson};
4903d77760a5db7990724b6901cea958a673ce0b39Anders Carlsson
50f3e7ce4bd9837cdab6a096235922865f95467d3dDouglas Gregortemplate struct X4<void>; // expected-note{{in instantiation of}}
51f3e7ce4bd9837cdab6a096235922865f95467d3dDouglas Gregortemplate struct X4<int>; // expected-note{{in instantiation of}}
52e2c31ff0bc622e6fd7d47d7e08b53840f3be6c89Douglas Gregor
53d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregorstruct Incomplete; // expected-note 2{{forward declaration}}
54e2c31ff0bc622e6fd7d47d7e08b53840f3be6c89Douglas Gregor
55e2c31ff0bc622e6fd7d47d7e08b53840f3be6c89Douglas Gregortemplate<typename T> struct X5 {
56e2c31ff0bc622e6fd7d47d7e08b53840f3be6c89Douglas Gregor  T f() { } // expected-error{{incomplete result type}}
57e2c31ff0bc622e6fd7d47d7e08b53840f3be6c89Douglas Gregor};
58e2c31ff0bc622e6fd7d47d7e08b53840f3be6c89Douglas Gregorvoid test_X5(X5<Incomplete> x5); // okay!
59e2c31ff0bc622e6fd7d47d7e08b53840f3be6c89Douglas Gregor
60e2c31ff0bc622e6fd7d47d7e08b53840f3be6c89Douglas Gregortemplate struct X5<Incomplete>; // expected-note{{instantiation}}
61d06f6ca61062f85926eb9d409eb3d4f8afcf93c7Douglas Gregor
62d06f6ca61062f85926eb9d409eb3d4f8afcf93c7Douglas Gregortemplate<typename T, typename U, typename V> struct X6 {
63d06f6ca61062f85926eb9d409eb3d4f8afcf93c7Douglas Gregor  U f(T t, U u, V v) {
64d06f6ca61062f85926eb9d409eb3d4f8afcf93c7Douglas Gregor    // IfStmt
65d06f6ca61062f85926eb9d409eb3d4f8afcf93c7Douglas Gregor    if (t > 0)
66d06f6ca61062f85926eb9d409eb3d4f8afcf93c7Douglas Gregor      return u;
6749f25ecf7ff358039ce4c9254b867f32110e660eDouglas Gregor    else {
6849f25ecf7ff358039ce4c9254b867f32110e660eDouglas Gregor      if (t < 0)
6918ef5e28a9a2677f8b1dce1fb2638d66e0a1621fDouglas Gregor        return v; // expected-error{{cannot initialize return object of type}}
7049f25ecf7ff358039ce4c9254b867f32110e660eDouglas Gregor    }
7149f25ecf7ff358039ce4c9254b867f32110e660eDouglas Gregor
72e06274d5c5c6b2decc9f217a8913b28f846bfcfaDouglas Gregor    if (T x = t) {
73e06274d5c5c6b2decc9f217a8913b28f846bfcfaDouglas Gregor      t = x;
74e06274d5c5c6b2decc9f217a8913b28f846bfcfaDouglas Gregor    }
757114cbab7eb6e8b714eb22f014327daf2c741c08John McCall    return v; // expected-error{{cannot initialize return object of type}}
76d06f6ca61062f85926eb9d409eb3d4f8afcf93c7Douglas Gregor  }
77d06f6ca61062f85926eb9d409eb3d4f8afcf93c7Douglas Gregor};
78d06f6ca61062f85926eb9d409eb3d4f8afcf93c7Douglas Gregor
79d06f6ca61062f85926eb9d409eb3d4f8afcf93c7Douglas Gregorstruct ConvertibleToInt {
80d06f6ca61062f85926eb9d409eb3d4f8afcf93c7Douglas Gregor  operator int() const;
81d06f6ca61062f85926eb9d409eb3d4f8afcf93c7Douglas Gregor};
82d06f6ca61062f85926eb9d409eb3d4f8afcf93c7Douglas Gregor
83d06f6ca61062f85926eb9d409eb3d4f8afcf93c7Douglas Gregortemplate struct X6<ConvertibleToInt, float, char>;
84d06f6ca61062f85926eb9d409eb3d4f8afcf93c7Douglas Gregortemplate struct X6<bool, int, int*>; // expected-note{{instantiation}}
850712d29123215e00b9e5b3c89746c90d9624830fAnders Carlsson
860712d29123215e00b9e5b3c89746c90d9624830fAnders Carlssontemplate <typename T> struct X7 {
870712d29123215e00b9e5b3c89746c90d9624830fAnders Carlsson  void f() {
880712d29123215e00b9e5b3c89746c90d9624830fAnders Carlsson    void *v = this;
890712d29123215e00b9e5b3c89746c90d9624830fAnders Carlsson  }
900712d29123215e00b9e5b3c89746c90d9624830fAnders Carlsson};
910712d29123215e00b9e5b3c89746c90d9624830fAnders Carlsson
920712d29123215e00b9e5b3c89746c90d9624830fAnders Carlssontemplate struct X7<int>;
934a2e2041edc63db687677325e113b39b9d123c40Douglas Gregor
944a2e2041edc63db687677325e113b39b9d123c40Douglas Gregortemplate<typename T> struct While0 {
954a2e2041edc63db687677325e113b39b9d123c40Douglas Gregor  void f(T t) {
964a2e2041edc63db687677325e113b39b9d123c40Douglas Gregor    while (t) {
974a2e2041edc63db687677325e113b39b9d123c40Douglas Gregor    }
984a2e2041edc63db687677325e113b39b9d123c40Douglas Gregor
994a2e2041edc63db687677325e113b39b9d123c40Douglas Gregor    while (T t2 = T()) ;
1004a2e2041edc63db687677325e113b39b9d123c40Douglas Gregor  }
1014a2e2041edc63db687677325e113b39b9d123c40Douglas Gregor};
1024a2e2041edc63db687677325e113b39b9d123c40Douglas Gregor
1034a2e2041edc63db687677325e113b39b9d123c40Douglas Gregortemplate struct While0<float>;
1049f3ca2a7747bd47f14d7693f333103fac29a24d2Douglas Gregor
1059f3ca2a7747bd47f14d7693f333103fac29a24d2Douglas Gregortemplate<typename T> struct Do0 {
1069f3ca2a7747bd47f14d7693f333103fac29a24d2Douglas Gregor  void f(T t) {
1079f3ca2a7747bd47f14d7693f333103fac29a24d2Douglas Gregor    do {
1089f3ca2a7747bd47f14d7693f333103fac29a24d2Douglas Gregor    } while (t); // expected-error{{not contextually}}
1099f3ca2a7747bd47f14d7693f333103fac29a24d2Douglas Gregor  }
1109f3ca2a7747bd47f14d7693f333103fac29a24d2Douglas Gregor};
1119f3ca2a7747bd47f14d7693f333103fac29a24d2Douglas Gregor
1129f3ca2a7747bd47f14d7693f333103fac29a24d2Douglas Gregorstruct NotConvertibleToBool { };
1139f3ca2a7747bd47f14d7693f333103fac29a24d2Douglas Gregortemplate struct Do0<ConvertibleToInt>;
1149f3ca2a7747bd47f14d7693f333103fac29a24d2Douglas Gregortemplate struct Do0<NotConvertibleToBool>; // expected-note{{instantiation}}
1155831c6a1efc47e6a19d82fe3dd25b5b8fef6979dDouglas Gregor
1165831c6a1efc47e6a19d82fe3dd25b5b8fef6979dDouglas Gregortemplate<typename T> struct For0 {
1175831c6a1efc47e6a19d82fe3dd25b5b8fef6979dDouglas Gregor  void f(T f, T l) {
1185831c6a1efc47e6a19d82fe3dd25b5b8fef6979dDouglas Gregor    for (; f != l; ++f) {
119861ce3178c70cfb0fa50baf685e1ad363538eaa9Douglas Gregor      if (*f)
120861ce3178c70cfb0fa50baf685e1ad363538eaa9Douglas Gregor        continue;
121861ce3178c70cfb0fa50baf685e1ad363538eaa9Douglas Gregor      else if (*f == 17)
122861ce3178c70cfb0fa50baf685e1ad363538eaa9Douglas Gregor        break;
1235831c6a1efc47e6a19d82fe3dd25b5b8fef6979dDouglas Gregor    }
1245831c6a1efc47e6a19d82fe3dd25b5b8fef6979dDouglas Gregor  }
1255831c6a1efc47e6a19d82fe3dd25b5b8fef6979dDouglas Gregor};
1265831c6a1efc47e6a19d82fe3dd25b5b8fef6979dDouglas Gregor
1275831c6a1efc47e6a19d82fe3dd25b5b8fef6979dDouglas Gregortemplate struct For0<int*>;
128ffce2df6ae280d354d51371282a579df1eb86876Anders Carlsson
129ffce2df6ae280d354d51371282a579df1eb86876Anders Carlssontemplate<typename T> struct Member0 {
130ffce2df6ae280d354d51371282a579df1eb86876Anders Carlsson  void f(T t) {
131ffce2df6ae280d354d51371282a579df1eb86876Anders Carlsson    t;
132ffce2df6ae280d354d51371282a579df1eb86876Anders Carlsson    t.f;
133ffce2df6ae280d354d51371282a579df1eb86876Anders Carlsson    t->f;
134ffce2df6ae280d354d51371282a579df1eb86876Anders Carlsson
135ffce2df6ae280d354d51371282a579df1eb86876Anders Carlsson    T* tp;
136ffce2df6ae280d354d51371282a579df1eb86876Anders Carlsson    tp.f; // expected-error{{member reference base type 'T *' is not a structure or union}}
137ffce2df6ae280d354d51371282a579df1eb86876Anders Carlsson    tp->f;
138ffce2df6ae280d354d51371282a579df1eb86876Anders Carlsson
139ffce2df6ae280d354d51371282a579df1eb86876Anders Carlsson    this->f;
1404e579922ada4e19618710878c32543322f86c9c8Anders Carlsson    this.f; // expected-error{{member reference base type 'Member0<T> *' is not a structure or union}}
141ffce2df6ae280d354d51371282a579df1eb86876Anders Carlsson  }
142ffce2df6ae280d354d51371282a579df1eb86876Anders Carlsson};
143dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor
144dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregortemplate<typename T, typename U> struct Switch0 {
145dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor  U f(T value, U v0, U v1, U v2) {
146dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor    switch (value) {
147dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor    case 0: return v0;
148dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor
149dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor    case 1: return v1;
150dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor
151dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor    case 2: // fall through
152dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor
153dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor    default:
154dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor      return  v2;
155dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor    }
156dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor  }
157dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor};
158dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor
159dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregortemplate struct Switch0<int, float>;
160dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor
161dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregortemplate<typename T, int I1, int I2> struct Switch1 {
162dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor  T f(T x, T y, T z) {
163dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor    switch (x) {
164dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor    case I1: return y; // expected-note{{previous}}
165dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor    case I2: return z; // expected-error{{duplicate}}
166dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor    default: return x;
167dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor    }
168dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor  }
169dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor};
170dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregor
171dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregortemplate struct Switch1<int, 1, 2>;
172dbb26db1d426fb6caaaf1b4fa47b46d1947c12c9Douglas Gregortemplate struct Switch1<int, 2, 2>; // expected-note{{instantiation}}
1735f1b9e689fa5c101512aef99225f2afea1673449Douglas Gregor
1745f1b9e689fa5c101512aef99225f2afea1673449Douglas Gregortemplate<typename T> struct IndirectGoto0 {
1755f1b9e689fa5c101512aef99225f2afea1673449Douglas Gregor  void f(T x) {
1765f1b9e689fa5c101512aef99225f2afea1673449Douglas Gregor    // FIXME: crummy error message below
1775f1b9e689fa5c101512aef99225f2afea1673449Douglas Gregor    goto *x; // expected-error{{incompatible}}
17876658235f9e350eab68bfbb4e88d0be2ad48e102Douglas Gregor
17976658235f9e350eab68bfbb4e88d0be2ad48e102Douglas Gregor  prior:
180632c9d26925f9aa8179607956c83ee348930b6d7Chris Lattner    T prior_label;
1817114cbab7eb6e8b714eb22f014327daf2c741c08John McCall    prior_label = &&prior; // expected-error{{assigning to 'int'}}
18276658235f9e350eab68bfbb4e88d0be2ad48e102Douglas Gregor
183632c9d26925f9aa8179607956c83ee348930b6d7Chris Lattner    T later_label;
1847114cbab7eb6e8b714eb22f014327daf2c741c08John McCall    later_label = &&later; // expected-error{{assigning to 'int'}}
18576658235f9e350eab68bfbb4e88d0be2ad48e102Douglas Gregor
18676658235f9e350eab68bfbb4e88d0be2ad48e102Douglas Gregor  later:
18776658235f9e350eab68bfbb4e88d0be2ad48e102Douglas Gregor    (void)(1+1);
1885f1b9e689fa5c101512aef99225f2afea1673449Douglas Gregor  }
1895f1b9e689fa5c101512aef99225f2afea1673449Douglas Gregor};
1905f1b9e689fa5c101512aef99225f2afea1673449Douglas Gregor
1915f1b9e689fa5c101512aef99225f2afea1673449Douglas Gregortemplate struct IndirectGoto0<void*>;
1925f1b9e689fa5c101512aef99225f2afea1673449Douglas Gregortemplate struct IndirectGoto0<int>; // expected-note{{instantiation}}
193d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregor
194d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregortemplate<typename T> struct TryCatch0 {
195d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregor  void f() {
196d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregor    try {
197a2762918ecc636c9af207ce2a9ce705edad2a444Douglas Gregor    } catch (T t) { // expected-warning{{incomplete type}} \
198d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregor                    // expected-error{{abstract class}}
199d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregor    } catch (...) {
200d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregor    }
201d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregor  }
202d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregor};
203d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregor
204d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregorstruct Abstract {
205d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregor  virtual void foo() = 0; // expected-note{{pure virtual}}
206d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregor};
207d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregor
208d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregortemplate struct TryCatch0<int>; // okay
209d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregortemplate struct TryCatch0<Incomplete*>; // expected-note{{instantiation}}
210d308e6201afd3a8a198c52ba034d35ed19d4bafeDouglas Gregortemplate struct TryCatch0<Abstract>; // expected-note{{instantiation}}
21131a08752eda39ca17154538e2f2587f8d339a1faAnders Carlsson
21231a08752eda39ca17154538e2f2587f8d339a1faAnders Carlsson// PR4383
21331a08752eda39ca17154538e2f2587f8d339a1faAnders Carlssontemplate<typename T> struct X;
21431a08752eda39ca17154538e2f2587f8d339a1faAnders Carlssontemplate<typename T> struct Y : public X<T> {
21531a08752eda39ca17154538e2f2587f8d339a1faAnders Carlsson  Y& x() { return *this; }
21631a08752eda39ca17154538e2f2587f8d339a1faAnders Carlsson};
217069ace5adc444a159003c29e85e166cee491ad39John McCall
218069ace5adc444a159003c29e85e166cee491ad39John McCall// Make sure our assertions don't get too uppity.
219069ace5adc444a159003c29e85e166cee491ad39John McCallnamespace test0 {
220069ace5adc444a159003c29e85e166cee491ad39John McCall  template <class T> class A { void foo(T array[10]); };
221069ace5adc444a159003c29e85e166cee491ad39John McCall  template class A<int>;
222069ace5adc444a159003c29e85e166cee491ad39John McCall}
223f7d72f5a4a3f0e610d77c6779ca3c21920a14bc7Douglas Gregor
224f7d72f5a4a3f0e610d77c6779ca3c21920a14bc7Douglas Gregornamespace PR7016 {
225f7d72f5a4a3f0e610d77c6779ca3c21920a14bc7Douglas Gregor  template<typename T> void f() { T x = x; }
226f7d72f5a4a3f0e610d77c6779ca3c21920a14bc7Douglas Gregor  template void f<int>();
227f7d72f5a4a3f0e610d77c6779ca3c21920a14bc7Douglas Gregor}
228c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor
229c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregornamespace PR9880 {
230c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor  struct lua_State;
231c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor  struct no_tag { char a; };			// (A)
232c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor  struct yes_tag { long a; long b; };	// (A)
233c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor
234c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor  template <typename T>
235c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor  struct HasIndexMetamethod {
236c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor    template <typename U>
237c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor    static no_tag check(...);
238c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor    template <typename U>
239c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor    static yes_tag check(char[sizeof(&U::luaIndex)]);
240c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor    enum { value = sizeof(check<T>(0)) == sizeof(yes_tag) };
241c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor  };
242c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor
243c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor  class SomeClass {
244c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor  public:
245c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor    int luaIndex(lua_State* L);
246c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor  };
247c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor
248c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor  int i = HasIndexMetamethod<SomeClass>::value;
249c056c1792eac0717640f1f48b3739cc9a98ee413Douglas Gregor}
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