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Is there an implicit type promotion in “float = float - float”?
Implicit type conversion rules in C++ operatorsImplicit type conversion in CHow is float variable auto-promoted to double type?What are POD types in C++?Do the parentheses after the type name make a difference with new?Writing containers that can handle implicit sharing, but turn it off for non-copyable types (like unique_ptr)?Implicit conversion in C++C++ Member variables confusionImplicit conversion of both operands for operator==C++ modulus operator with float using #define and own classImplicit conversion to float using avr-gcc: uint8_t vs. uint16_tReusing a float buffer for doubles without undefined behaviourWhen does implicit type conversion occur in C++?
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We are using QA-C for MISRA C++ conformance, but the tool spews out an error for code like this:
float a = foo();
float b = bar();
float c = a - b;
As far as I understand, this has no implicit type promotion as everything will happen in float-sized chunks, but the tool tells me that the subtraction causes one. Is there any situation where there might be implicit promotion?
c++ language-lawyer qa-c
asked Apr 26 at 7:45
Ken Y-NKen Y-N
7,996134776
|
show 8 more comments
We are using QA-C for MISRA C++ conformance, but the tool spews out an error for code like this:
float a = foo();
float b = bar();
float c = a - b;
As far as I understand, this has no implicit type promotion as everything will happen in float-sized chunks, but the tool tells me that the subtraction causes one. Is there any situation where there might be implicit promotion?
c++ language-lawyer qa-c
asked Apr 26 at 7:45
Ken Y-NKen Y-N
7,996134776
13
Would you mind adding the exact error that it gives you?
– Max Langhof
Apr 26 at 7:49
1
Consider also this Q&A, maybe, maybe the tool you are using is misinterpreting what's stated in the second part of that answer.
– Bob__
Apr 26 at 8:19
3
@Damon that's a non-sequitur;shortis promoted tointin this case and yet it makes sense to haveshort
– M.M
Apr 26 at 12:06
3
@Damon you already quoted the text that says "integral promotion shall be performed on both" (not "is allowed to happen" or whatever).
– M.M
Apr 26 at 12:31
2
Please provide the actual error message and actual code that produces that error message.
– Yakk - Adam Nevraumont
Apr 26 at 13:54
|
show 8 more comments
We are using QA-C for MISRA C++ conformance, but the tool spews out an error for code like this:
float a = foo();
float b = bar();
float c = a - b;
As far as I understand, this has no implicit type promotion as everything will happen in float-sized chunks, but the tool tells me that the subtraction causes one. Is there any situation where there might be implicit promotion?
c++ language-lawyer qa-c
asked Apr 26 at 7:45
Ken Y-NKen Y-N
7,996134776
We are using QA-C for MISRA C++ conformance, but the tool spews out an error for code like this:
float a = foo();
float b = bar();
float c = a - b;
As far as I understand, this has no implicit type promotion as everything will happen in float-sized chunks, but the tool tells me that the subtraction causes one. Is there any situation where there might be implicit promotion?
c++ language-lawyer qa-c
c++ language-lawyer qa-c
asked Apr 26 at 7:45
Ken Y-NKen Y-N
7,996134776
asked Apr 26 at 7:45
Ken Y-NKen Y-N
7,996134776
asked Apr 26 at 7:45
Ken Y-NKen Y-N
7,996134776
asked Apr 26 at 7:45
Ken Y-NKen Y-N
7,996134776
asked Apr 26 at 7:45
Ken Y-NKen Y-N
7,996134776
7,996134776
13
Would you mind adding the exact error that it gives you?
– Max Langhof
Apr 26 at 7:49
1
Consider also this Q&A, maybe, maybe the tool you are using is misinterpreting what's stated in the second part of that answer.
– Bob__
Apr 26 at 8:19
3
@Damon that's a non-sequitur;shortis promoted tointin this case and yet it makes sense to haveshort
– M.M
Apr 26 at 12:06
3
@Damon you already quoted the text that says "integral promotion shall be performed on both" (not "is allowed to happen" or whatever).
– M.M
Apr 26 at 12:31
2
Please provide the actual error message and actual code that produces that error message.
– Yakk - Adam Nevraumont
Apr 26 at 13:54
|
show 8 more comments
13
Would you mind adding the exact error that it gives you?
– Max Langhof
Apr 26 at 7:49
1
Consider also this Q&A, maybe, maybe the tool you are using is misinterpreting what's stated in the second part of that answer.
– Bob__
Apr 26 at 8:19
3
@Damon that's a non-sequitur;shortis promoted tointin this case and yet it makes sense to haveshort
– M.M
Apr 26 at 12:06
3
@Damon you already quoted the text that says "integral promotion shall be performed on both" (not "is allowed to happen" or whatever).
– M.M
Apr 26 at 12:31
2
Please provide the actual error message and actual code that produces that error message.
– Yakk - Adam Nevraumont
Apr 26 at 13:54
13
13
Would you mind adding the exact error that it gives you?
– Max Langhof
Apr 26 at 7:49
Would you mind adding the exact error that it gives you?
– Max Langhof
Apr 26 at 7:49
1
1
Consider also this Q&A, maybe, maybe the tool you are using is misinterpreting what's stated in the second part of that answer.
– Bob__
Apr 26 at 8:19
Consider also this Q&A, maybe, maybe the tool you are using is misinterpreting what's stated in the second part of that answer.
– Bob__
Apr 26 at 8:19
3
3
@Damon that's a non-sequitur;
short is promoted to int in this case and yet it makes sense to have short– M.M
Apr 26 at 12:06
@Damon that's a non-sequitur;
short is promoted to int in this case and yet it makes sense to have short– M.M
Apr 26 at 12:06
3
3
@Damon you already quoted the text that says "integral promotion shall be performed on both" (not "is allowed to happen" or whatever).
– M.M
Apr 26 at 12:31
@Damon you already quoted the text that says "integral promotion shall be performed on both" (not "is allowed to happen" or whatever).
– M.M
Apr 26 at 12:31
2
2
Please provide the actual error message and actual code that produces that error message.
– Yakk - Adam Nevraumont
Apr 26 at 13:54
Please provide the actual error message and actual code that produces that error message.
– Yakk - Adam Nevraumont
Apr 26 at 13:54
|
show 8 more comments
1 Answer
1
active
oldest
votes
There is no implicit promotion involved here.
When conversions involving binary operators are involved, they are called usual arithmetic conversions.
From C++ standard, [expr]/11:
11 Many binary operators that expect operands of arithmetic or enumeration type cause conversions and yield
result types in a similar way. The purpose is to yield a common type, which is also the type of the result.
This pattern is called the usual arithmetic conversions, which are defined as follows:
...
(11.4) — Otherwise, if either operand isfloat, the other shall be converted tofloat.
Since both operands are float in your example, there is no such conversion or promotion.
So this could be a false positive from the tool.
answered Apr 26 at 7:52
P.WP.W
19.6k41961
add a comment |
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1 Answer
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votes
There is no implicit promotion involved here.
When conversions involving binary operators are involved, they are called usual arithmetic conversions.
From C++ standard, [expr]/11:
11 Many binary operators that expect operands of arithmetic or enumeration type cause conversions and yield
result types in a similar way. The purpose is to yield a common type, which is also the type of the result.
This pattern is called the usual arithmetic conversions, which are defined as follows:
...
(11.4) — Otherwise, if either operand isfloat, the other shall be converted tofloat.
Since both operands are float in your example, there is no such conversion or promotion.
So this could be a false positive from the tool.
answered Apr 26 at 7:52
P.WP.W
19.6k41961
add a comment |
There is no implicit promotion involved here.
When conversions involving binary operators are involved, they are called usual arithmetic conversions.
From C++ standard, [expr]/11:
11 Many binary operators that expect operands of arithmetic or enumeration type cause conversions and yield
result types in a similar way. The purpose is to yield a common type, which is also the type of the result.
This pattern is called the usual arithmetic conversions, which are defined as follows:
...
(11.4) — Otherwise, if either operand isfloat, the other shall be converted tofloat.
Since both operands are float in your example, there is no such conversion or promotion.
So this could be a false positive from the tool.
answered Apr 26 at 7:52
P.WP.W
19.6k41961
add a comment |
There is no implicit promotion involved here.
When conversions involving binary operators are involved, they are called usual arithmetic conversions.
From C++ standard, [expr]/11:
11 Many binary operators that expect operands of arithmetic or enumeration type cause conversions and yield
result types in a similar way. The purpose is to yield a common type, which is also the type of the result.
This pattern is called the usual arithmetic conversions, which are defined as follows:
...
(11.4) — Otherwise, if either operand isfloat, the other shall be converted tofloat.
Since both operands are float in your example, there is no such conversion or promotion.
So this could be a false positive from the tool.
answered Apr 26 at 7:52
P.WP.W
19.6k41961
There is no implicit promotion involved here.
When conversions involving binary operators are involved, they are called usual arithmetic conversions.
From C++ standard, [expr]/11:
11 Many binary operators that expect operands of arithmetic or enumeration type cause conversions and yield
result types in a similar way. The purpose is to yield a common type, which is also the type of the result.
This pattern is called the usual arithmetic conversions, which are defined as follows:
...
(11.4) — Otherwise, if either operand isfloat, the other shall be converted tofloat.
Since both operands are float in your example, there is no such conversion or promotion.
So this could be a false positive from the tool.
answered Apr 26 at 7:52
P.WP.W
19.6k41961
edited Apr 26 at 8:01
answered Apr 26 at 7:52
P.WP.W
19.6k41961
answered Apr 26 at 7:52
P.WP.W
19.6k41961
answered Apr 26 at 7:52
P.WP.W
19.6k41961
19.6k41961
add a comment |
add a comment |
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13
Would you mind adding the exact error that it gives you?
– Max Langhof
Apr 26 at 7:49
1
Consider also this Q&A, maybe, maybe the tool you are using is misinterpreting what's stated in the second part of that answer.
– Bob__
Apr 26 at 8:19
3
@Damon that's a non-sequitur;
shortis promoted tointin this case and yet it makes sense to haveshort– M.M
Apr 26 at 12:06
3
@Damon you already quoted the text that says "integral promotion shall be performed on both" (not "is allowed to happen" or whatever).
– M.M
Apr 26 at 12:31
2
Please provide the actual error message and actual code that produces that error message.
– Yakk - Adam Nevraumont
Apr 26 at 13:54