Commit 7ef45f45 authored by Richard Smith's avatar Richard Smith
Browse files

P1957R2: conversion from a pointer to bool is considered narrowing. 

This is being implemented somewhat speculatively, to match GCC's
behavior.
parent db875f66

clang/lib/Sema/SemaOverload.cpp

+2 −3
Original line number Diff line number Diff line
@@ -328,9 +328,8 @@ NarrowingKind StandardConversionSequence::getNarrowingKind( 
      goto FloatingIntegralConversion;

    if (FromType->isIntegralOrUnscopedEnumerationType())

      goto IntegralConversion;

    // Boolean conversions can be from pointers and pointers to members

    // [conv.bool], and those aren't considered narrowing conversions.

    return NK_Not_Narrowing;

    // -- from a pointer type or pointer-to-member type to bool, or

    return NK_Type_Narrowing;















  // -- from a floating-point type to an integer type, or















  //

































clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p7-0x.cpp



+12
−2






























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@@ -180,9 +180,9 @@ void shrink_int() {













  Agg<bool> b2 = {1};  // OK















  Agg<bool> b3 = {-1};  // expected-error {{ cannot be narrowed }} expected-note {{silence}}





























  // Conversions from pointers to booleans aren't narrowing conversions.













  // Conversions from pointers to booleans are narrowing conversions.















  Agg<bool>* ptr = &b1;













  Agg<bool> b = {ptr};  // OK













  Agg<bool> b = {ptr};  // expected-error {{ cannot be narrowed }} expected-note {{silence}}































  Agg<short> ce1 = { Convert<int>(100000) }; // expected-error {{constant expression evaluates to 100000 which cannot be narrowed to type 'short'}} expected-note {{silence}} expected-warning {{changes value from 100000 to -31072}}















  Agg<char> ce2 = { ConvertVar<short>() }; // expected-error {{non-constant-expression cannot be narrowed from type 'short' to 'char'}} expected-note {{silence}}










@@ -240,3 +240,13 @@ void test_narrowed(Value<sizeof(int)> vi, Value<sizeof(double)> vd) {













  int &ir = check_narrowed<double>(vd);















  float &fr = check_narrowed<int>(vi);















}



























// * from a pointer type or a pointer-to-member type to bool.













void P1957R2(void *a, int *b, Agg<int> *c, int Agg<int>::*d) {













  Agg<bool> ta = {a}; // expected-error {{cannot be narrowed}} expected-note {{}}













  Agg<bool> tb = {b}; // expected-error {{cannot be narrowed}} expected-note {{}}













  Agg<bool> tc = {c}; // expected-error {{cannot be narrowed}} expected-note {{}}













  Agg<bool> td = {d}; // expected-error {{cannot be narrowed}} expected-note {{}}













}













template<bool> struct BoolParam {};













BoolParam<&P1957R2> bp; // expected-error {{not allowed in a converted constant expression}}
























clang/test/CXX/dcl.decl/dcl.init/dcl.init.list/p7-cxx11-nowarn.cpp



+0
−4






























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@@ -163,10 +163,6 @@ void shrink_int() {













  Agg<bool> b2 = {1};  // OK















  Agg<bool> b3 = {-1};  // expected-warning {{ cannot be narrowed }} expected-note {{silence}}





























  // Conversions from pointers to booleans aren't narrowing conversions.













  Agg<bool>* ptr = &b1;













  Agg<bool> b = {ptr};  // OK





























  Agg<short> ce1 = { Convert<int>(100000) }; // expected-warning {{constant expression evaluates to 100000 which cannot be narrowed to type 'short'}} expected-note {{silence}} expected-warning {{changes value from 100000 to -31072}}















  Agg<char> ce2 = { ConvertVar<short>() }; // expected-warning {{non-constant-expression cannot be narrowed from type 'short' to 'char'}} expected-note {{silence}}















}