gcc-warning

问题 I have the following code: struct A { short b; }; struct B { double a; }; void foo (struct B* src) { struct B* b = src; struct A* a = (struct A*)src; b->a = sin(rand()); if(a->b == rand()) { printf("Where are you strict aliasing warnings?\n"); } } I'm compiling the code with the following command line: gcc -c -std=c99 -Wstrict-aliasing=2 -Wall -fstrict-aliasing -O3 foo.c I'm using GCC 4.5.0. I expected the compiler to print out the warning: warning: dereferencing type-punned pointer will

问题 Is there any way to make gcc or clang warn about missing breaks in switch statements? Specifically, I almost always want case statements to end with breaks, and it would be great it I could get the compiler to complain if I don't. Even better would be if it would look for either a break statement or a "// fall through" comment. Is there a different solution people use to help themselves not screw this up? 回答1: With Clang trunk, use -Wimplicit-fallthrough . If you're using C++11, intentional

问题 What is the difference between a double ** and a double (*)[2]. If I understand well, a double ** is a pointer to a pointer of double, so it could be a 2D array of any size whereas double (*)[2] is a pointer to an array of double[2]. So if it is right, how can it be passed successfully to a function. For instance in : void pcmTocomplex(short *data, double *outm[2]) if I pass a double (*)[2] as a parameter, I have the following warning : warning: passing argument 2 of ‘pcmTocomplex’ from

问题 I am removing gcc warnings from a legacy code. Is it possible to suppress the warning "cast to pointer from integer of different size" through typecasting: example: some_struct *ptr = func() // func() returns an integer. Can someone please guide me how to resolve such gcc warnings? 回答1: First, if you can fix func (are allowed to modify its source), then fix it. If its computations can be done with pointers, then do them with pointers and return pointers. Sometimes there are valid reasons to

问题 How to disable all warnings on a few lines of code. Specific warnings can be disabled using GCC diagnostic feature, but is there a flag for all warnings. I tried this way but it doesn't work #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-wall" // some code #pragma GCC diagnostic pop 回答1: From here: http://dbp-consulting.com/tutorials/SuppressingGCCWarnings.html For version 4.6 or later, you can save the state of the user's diagnostic flags. You can insert this around the line

问题 I am currently working to debug a subroutine of some software that my boss has written back in the 90s. There seems to be a floating-point exception that occurs in a do loop of a particular subroutine: 16 irad=1,incmax rr1=rr2 rr2=rr2+rdiv if(rr1.gt.rlimit) goto 16 if(pts(irad).gt.0.0) then discrm=(rmsden(mt,irad)/pts(irad)) 1 -((average(mt,irad)**2)/(pts(irad)**2)) else discrm=0.0 endif if(discrm.ge.0.0) then rmsden(mt,irad)=sqrt(discrm) else rmsden(mt,irad)=0.0 endif average(mt,irad)

问题 I'm getting these two warnings (with GCC 4.2 on MacOSX): /Users/az/Programmierung/openlierox/build/Xcode/../../src/main.cpp:154:0 /Users/az/Programmierung/openlierox/build/Xcode/../../src/main.cpp:154: warning: 'startMainLockDetector()::MainLockDetector' declared with greater visibility than the type of its field 'startMainLockDetector()::MainLockDetector::<anonymous>' /Users/az/Programmierung/openlierox/build/Xcode/../../src/main.cpp:154:0 /Users/az/Programmierung/openlierox/build/Xcode/../.

问题 I'm getting these two warnings (with GCC 4.2 on MacOSX): /Users/az/Programmierung/openlierox/build/Xcode/../../src/main.cpp:154:0 /Users/az/Programmierung/openlierox/build/Xcode/../../src/main.cpp:154: warning: 'startMainLockDetector()::MainLockDetector' declared with greater visibility than the type of its field 'startMainLockDetector()::MainLockDetector::<anonymous>' /Users/az/Programmierung/openlierox/build/Xcode/../../src/main.cpp:154:0 /Users/az/Programmierung/openlierox/build/Xcode/../.

问题 I'm having some difficulty finding more information about GCC's aligned-new warning and the gcc -faligned-new option. Compiling on gcc 7.2.0 (without --std=c++17) and trying to define an aligned struct such as: struct alignas(64) Foo { int x; } Just doing a plain old: Foo * f = new Foo(); Gives me the following warning and suggestion: alignas.cpp:36:25: warning: ‘new’ of type ‘Foo’ with extended alignment 64 [-Waligned-new=] Foo * f = new Foo(); ^ alignas.cpp:36:25: note: uses ‘void* operator

问题 I'm having some difficulty finding more information about GCC's aligned-new warning and the gcc -faligned-new option. Compiling on gcc 7.2.0 (without --std=c++17) and trying to define an aligned struct such as: struct alignas(64) Foo { int x; } Just doing a plain old: Foo * f = new Foo(); Gives me the following warning and suggestion: alignas.cpp:36:25: warning: ‘new’ of type ‘Foo’ with extended alignment 64 [-Waligned-new=] Foo * f = new Foo(); ^ alignas.cpp:36:25: note: uses ‘void* operator