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https://github.com/capstone-engine/llvm-capstone.git
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fdf598eaf3
eliminating a bunch of redundant code and properly modeling how the captures of outside blocks/lambdas affect the types seen by inner captures. This new scheme makes two passes over the capturing scope stack. The first pass goes up the stack (from innermost to outermost), assessing whether the capture looks feasible and stopping when it either hits the scope where the variable is declared or when it finds an existing capture. The second pass then walks down the stack (from outermost to innermost), capturing the variable at each step and updating the captured type and the type that an expression referring to that captured variable would see. It also checks type-specific restrictions, such as the inability to capture an array within a block. Note that only the first odr-use of each variable needs to do the full walk; subsequent uses will find the capture immediately, so multiple walks need not occur. The same routine that builds the captures can also compute the type of the captures without signaling errors and without actually performing the capture. This functionality is used to determine the type of declaration references as well as implementing the weird decltype((x)) rule within lambda expressions. The capture code now explicitly takes sides in the debate over C++ core issue 1249, which concerns the type of captures within nested lambdas. We opt to use the more permissive, more useful definition implemented by GCC rather than the one implemented by EDG. llvm-svn: 150875
90 lines
4.2 KiB
C++
90 lines
4.2 KiB
C++
// RUN: %clang_cc1 -std=c++0x -Wno-unused-value -fsyntax-only -verify -fblocks %s
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namespace std { class type_info; };
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namespace ExplicitCapture {
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class C {
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int Member;
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static void Overload(int);
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void Overload();
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virtual C& Overload(float);
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void ImplicitThisCapture() {
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[](){(void)Member;}; // expected-error {{'this' cannot be implicitly captured in this context}}
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[&](){(void)Member;};
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[this](){(void)Member;};
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[this]{[this]{};};
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[]{[this]{};};// expected-error {{'this' cannot be implicitly captured in this context}}
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[]{Overload(3);};
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[]{Overload();}; // expected-error {{'this' cannot be implicitly captured in this context}}
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[]{(void)typeid(Overload());};
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[]{(void)typeid(Overload(.5f));};// expected-error {{'this' cannot be implicitly captured in this context}}
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}
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};
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void f() {
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[this] () {}; // expected-error {{'this' cannot be captured in this context}}
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}
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}
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namespace ReturnDeduction {
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void test() {
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[](){ return 1; };
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[](){ return 1; };
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[](){ return ({return 1; 1;}); };
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[](){ return ({return 'c'; 1;}); }; // expected-error {{must match previous return type}} \
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// expected-warning{{omitted result type}}
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[]()->int{ return 'c'; return 1; };
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[](){ return 'c'; return 1; }; // expected-error {{must match previous return type}}
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[]() { return; return (void)0; };
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[](){ return 1; return 1; }; // expected-warning{{omitted result type}}
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}
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}
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namespace ImplicitCapture {
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void test() {
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int a = 0; // expected-note 5 {{declared}}
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[]() { return a; }; // expected-error {{variable 'a' cannot be implicitly captured in a lambda with no capture-default specified}} expected-note {{begins here}}
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[&]() { return a; };
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[=]() { return a; };
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[=]() { int* b = &a; }; // expected-error {{cannot initialize a variable of type 'int *' with an rvalue of type 'const int *'}}
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[=]() { return [&]() { return a; }; };
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[]() { return [&]() { return a; }; }; // expected-error {{variable 'a' cannot be implicitly captured in a lambda with no capture-default specified}} expected-note {{lambda expression begins here}}
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[]() { return ^{ return a; }; };// expected-error {{variable 'a' cannot be implicitly captured in a lambda with no capture-default specified}} expected-note {{lambda expression begins here}}
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[]() { return [&a] { return a; }; }; // expected-error 2 {{variable 'a' cannot be implicitly captured in a lambda with no capture-default specified}} expected-note 2 {{lambda expression begins here}}
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[=]() { return [&a] { return a; }; }; //
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const int b = 2;
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[]() { return b; };
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union { // expected-note {{declared}}
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int c;
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float d;
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};
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d = 3;
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[=]() { return c; }; // expected-error {{unnamed variable cannot be implicitly captured in a lambda expression}}
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__block int e; // expected-note 3 {{declared}}
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[&]() { return e; }; // expected-error {{__block variable 'e' cannot be captured in a lambda expression}}
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[&e]() { return e; }; // expected-error 2 {{__block variable 'e' cannot be captured in a lambda expression}}
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int f[10]; // expected-note {{declared}}
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[&]() { return f[2]; };
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(void) ^{ return []() { return f[2]; }; }; // expected-error {{variable 'f' cannot be implicitly captured in a lambda with no capture-default specified}} \
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// expected-note{{lambda expression begins here}}
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struct G { G(); G(G&); int a; }; // expected-note 6 {{not viable}}
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G g;
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[=]() { const G* gg = &g; return gg->a; }; // expected-warning{{omitted result type}}
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[=]() { return [=]{ const G* gg = &g; return gg->a; }(); }; // expected-error {{no matching constructor for initialization of 'ImplicitCapture::G'}} \
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// expected-warning{{omitted result type}}
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(void)^{ return [=]{ const G* gg = &g; return gg->a; }(); }; // expected-error 2 {{no matching constructor for initialization of 'const ImplicitCapture::G'}} \
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// expected-warning{{omitted result type}}
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const int h = a; // expected-note {{declared}}
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[]() { return h; }; // expected-error {{variable 'h' cannot be implicitly captured in a lambda with no capture-default specified}} expected-note {{lambda expression begins here}}
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}
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}
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