[clang] Objective-C encoding of `BOOL*` is wrong

[madsmtm]

The following program:

#import <stdio.h>

typedef signed char BOOL;
typedef signed char TYPEDEF;

int main() {
    printf("signed char* encoding: %s\n", @encode(signed char*));
    printf("TYPEDEF* encoding: %s\n", @encode(TYPEDEF*));
    printf("BOOL* encoding: %s\n", @encode(BOOL*));
    return 0;
}

Is supposed to output the following on x86_64 (godbolt Clang 15, Godbolt GCC 13.2):

signed char* encoding: *
TYPEDEF* encoding: *
BOOL* encoding: ^c

But since Clang 16, it outputs (godbolt Clang 18):

signed char* encoding: *
TYPEDEF* encoding: *
BOOL* encoding: *

---

Clang seemingly has code to support this, see

llvm-project/clang/lib/AST/ASTContext.cpp

Lines 7696 to 7704 in 2bf7ddf

	// This returns true if a type has been typedefed to BOOL:
	// typedef <type> BOOL;
	static bool isTypeTypedefedAsBOOL(QualType T) {
	if (const auto *TT = dyn_cast<TypedefType>(T))
	if (IdentifierInfo *II = TT->getDecl()->getIdentifier())
	return II->isStr("BOOL");
	return false;
	}

and

llvm-project/clang/lib/AST/ASTContext.cpp

Lines 8356 to 8362 in 2bf7ddf

	if (PointeeTy->isCharType()) {
	// char pointer types should be encoded as '*' unless it is a
	// type that has been typedef'd to 'BOOL'.
	if (!isTypeTypedefedAsBOOL(PointeeTy)) {
	S += '*';
	return;
	}

, but for some reason these code paths are now no longer correctly triggered?

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Mads Marquart (madsmtm)

The following program:

#import <stdio.h>

typedef signed char BOOL;
typedef signed char TYPEDEF;

int main() {
    printf("signed char* encoding: %s\n", @<!-- -->encode(signed char*));
    printf("TYPEDEF* encoding: %s\n", @<!-- -->encode(TYPEDEF*));
    printf("BOOL* encoding: %s\n", @<!-- -->encode(BOOL*));
    return 0;
}

Is supposed to output the following on x86_64 (godbolt Clang 15, Godbolt GCC 13.2):

signed char* encoding: *
TYPEDEF* encoding: *
BOOL* encoding: ^c

But since Clang 16, it outputs (godbolt Clang 18):

signed char* encoding: *
TYPEDEF* encoding: *
BOOL* encoding: *

---

Clang seemingly has code to support this, see

llvm-project/clang/lib/AST/ASTContext.cpp

Lines 7696 to 7704 in 2bf7ddf

	// This returns true if a type has been typedefed to BOOL:
	// typedef <type> BOOL;
	static bool isTypeTypedefedAsBOOL(QualType T) {
	if (const auto *TT = dyn_cast<TypedefType>(T))
	if (IdentifierInfo *II = TT->getDecl()->getIdentifier())
	return II->isStr("BOOL");
	return false;
	}

and

llvm-project/clang/lib/AST/ASTContext.cpp

Lines 8356 to 8362 in 2bf7ddf

	if (PointeeTy->isCharType()) {
	// char pointer types should be encoded as '*' unless it is a
	// type that has been typedef'd to 'BOOL'.
	if (!isTypeTypedefedAsBOOL(PointeeTy)) {
	S += '*';
	return;
	}

, but for some reason these code paths are now no longer correctly triggered?