Can't fully activate `-Wconsumed` using `#pragma clang diagnostic`

[comex]

Bugzilla Link	42854
Version	trunk
OS	All
CC	@DougGregor,@zygoloid

Extended Description

If you activate -Wconsumed using a pragma rather than on the command line, it seemingly doesn't trigger the consumed analysis pass.

Given the following example code:

#pragma clang diagnostic error "-Wconsumed"

struct [[clang::consumable(unconsumed)]] Linear {
    [[clang::return_typestate(unconsumed)]]
    Linear() {}
    [[clang::callable_when(consumed)]]
    ~Linear() {}
};

void a() {
    Linear l;
}

Compiling the code as is, without passing -Wconsumed on the command line, I get no warnings or errors.

The pragma does enable -Wconsumed warnings about malformed declarations: if I e.g. comment out the consumable attribute on Linear, I get:

error: consumed analysis attribute is attached to member of class 'Linear' which isn't marked as consumable [-Werror,-Wconsumed]

However, without commenting anything out, I expect this diagnostic from a():

error: invalid invocation of method '~Linear' on object 'l' while it is in the 'unconsumed' state [-Werror,-Wconsumed]

I get this if and only if I pass -Wconsumed on the command line.

Tested on Compiler Explorer's "x86-64 clang (trunk)".

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: None (comex)

| | | | --- | --- | | Bugzilla Link | [42854](https://llvm.org/bz42854) | | Version | trunk | | OS | All | | CC | @DougGregor,@zygoloid |

Extended Description

If you activate -Wconsumed using a pragma rather than on the command line, it seemingly doesn't trigger the consumed analysis pass.

Given the following example code:

#pragma clang diagnostic error "-Wconsumed"

struct [[clang::consumable(unconsumed)]] Linear {
    [[clang::return_typestate(unconsumed)]]
    Linear() {}
    [[clang::callable_when(consumed)]]
    ~Linear() {}
};

void a() {
    Linear l;
}

Compiling the code as is, without passing -Wconsumed on the command line, I get no warnings or errors.

The pragma does enable -Wconsumed warnings about malformed declarations: if I e.g. comment out the consumable attribute on Linear, I get:

error: consumed analysis attribute is attached to member of class 'Linear' which isn't marked as consumable [-Werror,-Wconsumed]

However, without commenting anything out, I expect this diagnostic from a():

error: invalid invocation of method '~Linear' on object 'l' while it is in the 'unconsumed' state [-Werror,-Wconsumed]

I get this if and only if I pass -Wconsumed on the command line.

Tested on Compiler Explorer's "x86-64 clang (trunk)".

[AaronBallman]

The issue is that analysis-based warnings do not correctly check for whether the diagnostic is enabled or not. The default policy is set here

llvm-project/clang/lib/Sema/AnalysisBasedWarnings.cpp

Line 2497 in 3ed8363

return (unsigned)!D.isIgnored(diag, SourceLocation());

but it's using an invalid source location for the check because it's a default policy.

Everything else uses the default policy. I think getDefaultPolicy() perhaps needs to take a SourceLocation of some kind so we can properly set the flags based on the state of the compiler at the time the policy is needed.