llvm-project/clang/test/CodeGenCXX/cxx1y-variable-template-linkage.cpp
Sirraide 12f78e740c
[Clang] [NFC] Fix unintended -Wreturn-type warnings everywhere in the test suite (#123464)
In preparation of making `-Wreturn-type` default to an error (as there
is virtually no situation where you’d *want* to fall off the end of a
function that is supposed to return a value), this patch fixes tests
that have relied on this being only a warning, of which there seem 
to be 3 kinds:

1. Tests which for no apparent reason have a function that triggers the
warning.

I suspect that a lot of these were on accident (or from before the
warning was introduced), since a lot of people will open issues w/ their
problematic code in the `main` function (which is the one case where you
don’t need to return from a non-void function, after all...), which
someone will then copy, possibly into a namespace, possibly renaming it,
the end result of that being that you end up w/ something that
definitely is not `main` anymore, but which still is declared as
returning `int`, and which still has no return statement (another reason
why I think this might apply to a lot of these is because usually the
actual return type of such problematic functions is quite literally
`int`).
  
A lot of these are really old tests that don’t use `-verify`, which is
why no-one noticed or had to care about the extra warning that was
already being emitted by them until now.

2. Tests which test either `-Wreturn-type`, `[[noreturn]]`, or what
codegen and sanitisers do whenever you do fall off the end of a
function.

3. Tests where I struggle to figure out what is even being tested
(usually because they’re Objective-C tests, and I don’t know
Objective-C), whether falling off the end of a function matters in the
first place, and tests where actually spelling out an expression to
return would be rather cumbersome (e.g. matrix types currently don’t
support list initialisation, so I can’t write e.g. `return {}`).

For tests that fall into categories 2 and 3, I just added
`-Wno-error=return-type` to the `RUN` lines and called it a day. This
was especially necessary for the former since `-Wreturn-type` is an
analysis-based warning, meaning that it is currently impossible to test
for more than one occurrence of it in the same compilation if it
defaults to an error since the analysis pass is skipped for subsequent
functions as soon as an error is emitted.

I’ve also added `-Werror=return-type` to a few tests that I had already
updated as this patch was previously already making the warning an error
by default, but we’ve decided to split that into two patches instead.
2025-01-18 19:16:33 +01:00

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// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -std=c++1y -O1 -disable-llvm-passes %s -o - | FileCheck %s -check-prefix=CHECKA -check-prefix=CHECK
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -std=c++1y -O1 -disable-llvm-passes -fcxx-exceptions %s -o - | FileCheck %s -check-prefix=CHECKB -check-prefix=CHECK
// expected-no-diagnostics
// The variable template specialization x<Foo> generated in each file
// should be 'internal global' and not 'linkonce_odr global'.
template <typename T> int x = 42;
// CHECK-DAG: @_Z1xIiE = linkonce_odr global
// CHECK-DAG: @_Z1xIZL3foovE3FooE = internal global
// 'static' affects the linkage of the global
template <typename T> static int y = 42;
// CHECK-DAG: @_ZL1yIiE = internal global
// CHECK-DAG: @_ZL1yIZL3foovE3FooE = internal global
// 'const' does not
template <typename T> const int z = 42;
// CHECK-DAG: @_Z1zIiE = linkonce_odr constant
// CHECK-DAG: @_Z1zIZL3foovE3FooE = internal constant
template <typename T> T t = 42;
// CHECK-DAG: @_Z1tIiE = linkonce_odr global
// CHECK-DAG: @_Z1tIKiE = linkonce_odr constant
int mode;
// CHECK-DAG: define internal noundef nonnull align 4 dereferenceable(4) ptr @_ZL3foov(
static const int &foo() {
struct Foo { };
switch (mode) {
case 0:
// CHECK-DAG: @_Z1xIiE
return x<int>;
case 1:
// CHECK-DAG: @_Z1xIZL3foovE3FooE
return x<Foo>;
case 2:
// CHECK-DAG: @_ZL1yIiE
return y<int>;
case 3:
// CHECK-DAG: @_ZL1yIZL3foovE3FooE
return y<Foo>;
case 4:
// CHECK-DAG: @_Z1zIiE
return z<int>;
case 5:
// CHECK-DAG: @_Z1zIZL3foovE3FooE
return z<Foo>;
case 6:
// CHECK-DAG: @_Z1tIiE
return t<int>;
case 7:
// CHECK-DAG: @_Z1tIKiE
return t<const int>;
}
static int x;
return x;
}
#if !__has_feature(cxx_exceptions) // File A
// CHECKA-DAG: define{{.*}} nonnull align 4 dereferenceable(4) ptr @_Z3barv(
const int &bar() {
// CHECKA-DAG: call noundef nonnull align 4 dereferenceable(4) ptr @_ZL3foov()
return foo();
}
#else // File B
// CHECKB-DAG: declare noundef nonnull align 4 dereferenceable(4) ptr @_Z3barv(
const int &bar();
int main() {
// CHECKB-DAG: call noundef nonnull align 4 dereferenceable(4) ptr @_Z3barv()
// CHECKB-DAG: call noundef nonnull align 4 dereferenceable(4) ptr @_ZL3foov()
&bar() == &foo() ? throw 0 : (void)0; // Should not throw exception at runtime.
}
#endif // end of Files A and B