GCC 16.1 Manual "Using the GNU Compiler Collection -- For gcc version 16.1.0"

[ilazaric]

found at https://gcc.gnu.org/onlinedocs/
https://gcc.gnu.org/onlinedocs/gcc-16.1.0/gcc.pdf

gcc.pdf

[ilazaric]

-Q --help seems useful

$ g++ foo.cpp -fconstexpr-ops-limit=1337 -Q --help=c++ | grep constexpr-ops
  -fconstexpr-ops-limit=<number> 	1337 bytes

[ilazaric]

-fno-access-control might be nice in some tests

-fno-access-control
Turn off all access checking. This switch is mainly useful for working around
bugs in the access control code.

[ilazaric]

Not the option, but in description:

-fcheck-new
Check that the pointer returned by operator new is non-null before attempting
to modify the storage allocated. This check is normally unnecessary because
the C++ standard specifies that operator new only returns 0 if it is declared
throw(), in which case the compiler always checks the return value even without
this option. In all other cases, when operator new has a non-empty exception
specification, memory exhaustion is signalled by throwing std::bad_alloc.
See also ‘new (nothrow)’.

so new can return 0 if throw()

[ilazaric]

-Wno-abbreviated-auto-in-template-arg
Disable the error for an auto placeholder type used within a template argument
list to declare a C++20 abbreviated function template, e.g.
void f(S<auto>);
This feature was proposed in the Concepts TS, but was not adopted into C++20;
in the standard, a placeholder in a parameter declaration must appear as a
decl-specifier. The error can also be reduced to a warning by -fpermissive or
-Wno-error=abbreviated-auto-in-template-arg.

you can also attach concepts to the auto:

auto sum(const std::vector<std::integral auto>&);

[ilazaric]

interesting warnings:

-Weffc++
-Wold-style-cast
-Wsign-promo
-Wno-template-body
-Wsuggest-override

weakly interesting:

-Wmismatched-tags
-Wno-terminate

[ilazaric]

-Wcatch-value
-Wcatch-value=n (C++ and Objective-C++ only)
Warn about catch handlers that do not catch via reference. With -Wcatch-
value=1 (or -Wcatch-value for short) warn about polymorphic class types
that are caught by value. With -Wcatch-value=2 warn about all class types
that are caught by value. With -Wcatch-value=3 warn about all types that
are not caught by reference. -Wcatch-value is enabled by -Wall.

[ilazaric]

-Wsuggest-final-types
Warn about types with virtual methods where code quality would be improved
if the type were declared with the C++11 final specifier, or, if possible, de-
clared in an anonymous namespace. This allows GCC to more aggressively
devirtualize the polymorphic calls. This warning is more effective with link-
time optimization, where the information about the class hierarchy graph is
more complete.

-Wsuggest-final-methods
Warn about virtual methods where code quality would be improved if the
method were declared with the C++11 final specifier, or, if possible, its type
were declared in an anonymous namespace or with the final specifier. This
warning is more effective with link-time optimization, where the information
about the class hierarchy graph is more complete. It is recommended to first
consider suggestions of -Wsuggest-final-types and then rebuild with new
annotations.

[ilazaric]

-fdiagnostics-urls[=WHEN]
Use escape sequences to embed URLs in diagnostics. For example, when
-fdiagnostics-show-option emits text showing the command-line option
controlling a diagnostic, embed a URL for documentation of that option.
...

[ilazaric]

-fdiagnostics-parseable-fixits
Emit fix-it hints in a machine-parseable format, suitable for consumption by
IDEs. For each fix-it, a line will be printed after the relevant diagnostic, starting
with the string “fix-it:”.

maybe add to emacs?

[ilazaric]

-fdiagnostics-show-template-tree
In the C++ frontend, when printing diagnostics showing mismatching template
types, such as:
could not convert 'std::map<int, std::vector<double> >()'
from 'map<[...],vector<double>>' to 'map<[...],vector<float>>
the -fdiagnostics-show-template-tree flag enables printing a tree-like
structure showing the common and differing parts of the types, such as:
map<
[...],
vector<
[double != float]>>
The parts that differ are highlighted with color (“double” and “float” in this
case).

cute

[ilazaric]

-fdiagnostics-{add,set}-output=DIAGNOSTICS-OUTPUT-SPEC can generate html

[ilazaric]

-Wswitch-default
-Wswitch-enum

[ilazaric]

-Wuseless-cast
Warn when an expression is cast to its own type.