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travis CI fixes
This commit is contained in:
Sergey Zubkov
parent
aabfe119d3
commit
85cb14703c
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@ -2162,7 +2162,7 @@ We might write
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}
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istream& in = *inp;
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This violated the ruly [against uninitialized variables](#Res-always),
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This violated the rule [against uninitialized variables](#Res-always),
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the rule against [ignoring ownership](#Ri-raw),
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and the rule [against magic constants](#Res-magic) .
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In particular, someone has to remember to somewhere write
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@ -2171,27 +2171,27 @@ In particular, someone has to remember to somewhere write
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We could handle this particular example by using `unique_ptr` with a special deleter that does nothing for `cin`,
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but that's complicated for novices (who can easily encounter this problem) and the example is an example of a more general
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problem where a property that we would like to consider static (here, ownership) needs infrequesntly be addressed
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problem where a property that we would like to consider static (here, ownership) needs infrequently be addressed
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at run time.
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The common, most frequent, and safest examples can be handled statically, so we don't want to add cost and complexity to those.
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But we must also cope with the uncommon, less-safe, and necessarily more expensive cases.
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Such examples are discussed in [[Str15]](http://www.stroustrup.com/resource-model.pdf).
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So, we write a class
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So, we write a class
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class Istream { [[gsl::suppress(lifetime)]]
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public:
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enum Opt { from_line=1 };
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enum Opt { from_line = 1 };
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Istream() { }
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Istream(zstring p) :owned{true}, inp{new ifstream{p}} {} // read from file
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Istream(zstring p,Opt) :owned{true}, inp{new istringstream{p}} {} // read from command line
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Istream(zstring p, Opt) :owned{true}, inp{new istringstream{p}} {} // read from command line
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~Itream() { if (owned) delete inp; }
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operator istream& () { return *inp; }
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private:
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bool owned = false;
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istream* inp = &cin;
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};
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Now, the dynamic nature of `istream` ownership has been encapsulated.
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Presumably, a bit of checking for potential errors would be added in real code.
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@ -6114,7 +6114,7 @@ This is not just slow, but if a memory allocation occurs for the elements in `tm
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(Simple) When a class has a `swap` member function, it should be declared `noexcept`.
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### <a name="Rc-swap-noexcept"></a>: C.85: Make `swap` `noexcept`
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### <a name="Rc-swap-noexcept"></a>C.85: Make `swap` `noexcept`
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##### Reason
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@ -7134,7 +7134,7 @@ This rule is about using `final` on classes with virtual functions meant to be i
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##### Note
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Capping an individual virtual function with `final` is error-prone as `final` can easily be overlooked when defining/overriding a set of functions.
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Fortunately, the compiler catches such mistakes: You cannot re-declare/re-open a `final` member a derived class.
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Fortunately, the compiler catches such mistakes: You cannot re-declare/re-open a `final` member in a derived class.
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##### Note
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@ -11889,7 +11889,7 @@ This also applies to `%`.
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Choosing `unsigned` implies many changes to the usual behavior of integers, including modulo arithmetic,
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can suppress warnings related to overflow,
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and opens the door for errors related to signed/unsigned mixes.
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Using `unsigned` doesn't actually eliminate the possibility of negative values.
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Using `unsigned` doesn't actually eliminate the possibility of negative values.
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##### Example
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@ -11904,32 +11904,32 @@ Consider:
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unsigned area(unsigned height, unsigned width) { return height*width; } // [see also](#Ri-expects)
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// ...
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int height;
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cin>>height;
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auto a = area(height,2); // if the input is -2 a becomes 4294967292
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cin >> height;
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auto a = area(height, 2); // if the input is -2 a becomes 4294967292
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Remember that `-1` when assigned to an `unsigned int` becomes the largest `unsigned int`.
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Also, since unsigned arithmetic is modulo arithmentic the multiplication didn't overflow, it wrapped around.
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Also, since unsigned arithmetic is modulo arithmetic the multiplication didn't overflow, it wrapped around.
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##### Example
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unsigned max = 100000; // "accidental typo", I mean to say 10'000
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unsigned max = 100000; // "accidental typo", I mean to say 10'000
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unsigned short x = 100;
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while (x<max) x += 100; // infinite loop
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while (x < max) x += 100; // infinite loop
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Had `x` been a signed `short`, we could have warned about the undefined behavior upon overflow.
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##### Alternatives
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* use signed integers and check for `x>= 0`
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* use signed integers and check for `x >= 0`
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* use a positive integer type
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* use an integer subrange type
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* `Assert(-1<x)`
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* `Assert(-1 < x)`
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For example
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struct Positive {
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int val;
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Positive(int x) :val{x} { Assert(0<x); }
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Positive(int x) :val{x} { Assert(0 < x); }
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operator int() { return val; }
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};
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@ -11957,17 +11957,21 @@ To enable better error detection.
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##### Example, bad
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vector<int> vec {1,2,3,4,5};
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vector<int> vec {1, 2, 3, 4, 5};
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for (int i=0; i<vec.size(); i+=2) cout << vec[i] << '\n'; // mix int and unsigned
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for (unsigned i=0; i<vec.size(); i+=2) cout << vec[i] << '\n'; // risk wraparound
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for (vector<int>::size_type i=0; i<vec.size(); i+=2) cout << vec[i] << '\n'; // verbose
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for (auto i=0; i<vec.size(); i+=2) cout << vec[i] << '\n'; // mix int and unsigned
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for (int i=0; i < vec.size(); i+=2) // mix int and unsigned
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cout << vec[i] << '\n';
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for (unsigned i=0; i < vec.size(); i+=2) // risk wraparound
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cout << vec[i] << '\n';
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for (vector<int>::size_type i=0; i < vec.size(); i+=2) // verbose
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cout << vec[i] << '\n';
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for (auto i=0; i < vec.size(); i+=2) // mix int and unsigned
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cout << vec[i] << '\n';
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##### Note
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The built-in array uses signed subscripts.
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The standard-library containers use unsigned sunscripts.
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The standard-library containers use unsigned subscripts.
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Thus, no perfect and fully compatible solution is possible.
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Given the known problems with unsigned and signed/unsigned mixtures, better stick to (signed) integers.
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@ -14266,7 +14270,7 @@ Instead, use a reference:
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catch (exception& e) { /* ... */ }
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of - typically better stil - a `const` reference:
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of - typically better still - a `const` reference:
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catch (const exception& e) { /* ... */ }
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@ -17545,15 +17549,15 @@ Avoid accidentally becoming dependent on implementation details and logically se
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##### Example
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#include<iostream>
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#include <iostream>
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using namespace std;
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void use() // bad
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{
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string s;
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cin >> s; // fine
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getline(cin,s); // error: getline() not defined
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if (s=="surprise") { // error == not defined
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getline(cin, s); // error: getline() not defined
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if (s == "surprise") { // error == not defined
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// ...
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}
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}
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@ -17565,16 +17569,16 @@ or even an occasional "`string`s cannot be compared with `==`).
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The solution is to explicitly `#include<string>`:
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#include<iostream>
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#include<string>
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#include <iostream>
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#include <string>
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using namespace std;
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void use()
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{
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string s;
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cin >> s; // fine
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getline(cin,s); // fine
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if (s=="surprise") { // fine
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getline(cin, s); // fine
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if (s == "surprise") { // fine
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// ...
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}
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}
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@ -17586,12 +17590,12 @@ For example:
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// basic_std_lib.h:
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#include<vector>
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#include<string>
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#include<map>
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#include<iostream>
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#include<random>
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#include<vector>
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#include <vector>
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#include <string>
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#include <map>
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#include <iostream>
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#include <random>
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#include <vector>
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a user can now get that set of declarations with a single `#include`"
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@ -1,4 +1,5 @@
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'
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10'000
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0xFF0000
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0b0101'0101
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10x
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@ -184,6 +185,7 @@ g1
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g2
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GCC
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Geosoft
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getline
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getx
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GFM
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Girou
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@ -205,7 +207,9 @@ hnd
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homebrew
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HPL
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href
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HTTP
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Hyslop
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i2
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IDE
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IDEs
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IEC
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@ -480,6 +484,7 @@ stmt
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str
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strdup
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strlen
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Str15
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Stroustrup
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Stroustrup00
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Stroustrup05
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@ -527,6 +532,8 @@ typeid
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typename
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typesafe
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UB
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u1
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u2
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unaliased
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uncompromised
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underuse
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