Adding more compiler warnings by default

[aminya]

There are other Clang warnings that we have not added. We have already enabled the most pedantic ones, so I think adding these will complete the list and would be beneficial.

-Wformat-overflow
-Wformat-nonliteral
-Wformat-truncation=2
-fno-common
-Wcast-qual
-Wdeprecated
-Wmissing-declarations
-Wmissing-prototypes
-Wnested-externs
-Wold-style-definition
-Wpointer-arith
-Wsign-compare
-Wstrict-prototypes
-Wundef
-Wwrite-strings

https://clang.llvm.org/docs/DiagnosticsReference.html

[lefticus]

I fully agree that we should do a pass over the existing warning flags set, but I think it should be more nuanced than this.

Right now I know there is some redundant flags. For example, the -Wwrite-strings is listed as "enabled by default" on Clang's warning page. I know there are others that are currently enabled that we should consider removing while we add new ones that were not previously covered.

Another one to consider is -pedantic-errors, which according to the GCC documentation does "This is not equivalent to -Werror=pedantic, since there are errors enabled by this option and not enabled by the latter and vice versa." but it gives no further explanation.

[ljishen]

Some of these warnings may only be available for C and not C++ in GCC. For example, -Wmissing-prototypes, -Wnested-externs, -Wold-style-definition, and -Wstrict-prototypes.

[janwilmans]

more suggestions:

-Wconversion 
-Wsign-conversion 
-Wmissing-include-dirs 
-Wformat=2 
-Wunused 
-Wunused-variable 
-Wcast-align 
-Wno-vla 
-Wnull-dereference
-Wshadow

[janwilmans]

and (but only for C++) -Wnon-virtual-dtor -Woverloaded-virtual

[ClausKlein]

'-Wno-vla' seems to disable a warning?

[aminya]

more suggestions:

-Wconversion 
-Wsign-conversion 
-Wmissing-include-dirs 
-Wformat=2 
-Wunused 
-Wunused-variable 
-Wcast-align 
-Wno-vla 
-Wnull-dereference
-Wshadow

Many of these are already enabled. Could you find the ones that are not?
https://github.com/aminya/project_options/blob/main/src/CompilerWarnings.cmake

[aminya]

'-Wno-vla'

It disallows the use of variable-length C arrays. I am wondering if this is already covered by -Wpedantic