[clang][modules] Mark builtin header 'inttypes.h' for modules

[benlangmuir]

Summary

Like the other enumerated builtin headers, inttypes.h can be declared by another system module.

rdar://113924039

[iana]

Can you add @vsapsai to the reviewers please? He was looking at this one a year or two ago.

[benlangmuir]

Add missing test updates: tests using the Inputs/System/usr/include should be using -internal-isystem to get the correct search path order with respect to the resource dir. The tests that were previously using -isystem were only working before because the other headers wrap their #include_next in __has_include_next, which was causing them to silently be missing these headers. With inttypes.h the include_next is unguarded, which revealed the issue. Note: even if we someday add the has_include_next guard to inttypes.h the test change is still correct.

[vsapsai]

Running the tests locally fails with

lib/clang/18/include/inttypes.h:21:15: fatal error: 'inttypes.h' file not found
   21 | #include_next <inttypes.h>
      |               ^~~~~~~~~~~~

Is it something wrong with my local configuration?

Also want to study the previous discussion on this subject.

[iana]

I was talking to Ben about this one a little today since I ended up needing to make the same -isystem/-I -> -internal-isystem switch in some of the unit tests in D159064, and also add a clang/test/Modules/Inputs/System/usr/include/inttypes.h.

I think it's just plain not supported to put isysroot/usr/include before resource-dir/include. That said, fusing resource-dir/include/inttypes.h with isysroot/usr/include is probably going to break the projects that messed that up, whereas having the two in different modules probably won't.

So even though this change is correct, IMO it's not worth the trouble since we have to do D159064 to make the libc++ cstd header work anyway.

clang/lib/Lex/ModuleMap.cpp

 }
 
 /// Determine whether the given file name is the name of a builtin
 /// header, supplied by Clang to replace, override, or augment existing system
 /// headers.
 bool ModuleMap::isBuiltinHeader(StringRef FileName) {
   return llvm::StringSwitch<bool>(FileName)
            .Case("float.h", true)
+           .Case("inttypes.h", true)
            .Case("iso646.h", true)
            .Case("limits.h", true)
            .Case("stdalign.h", true)
            .Case("stdarg.h", true)
            .Case("stdatomic.h", true)
            .Case("stdbool.h", true)
            .Case("stddef.h", true)
            .Case("stdint.h", true)

clang/test/Modules/Inputs/System/usr/include/module.map

 module cstd [system] {
   // Only in compiler support directory
   module float_constants {
     header "float.h"
   }
 
+  // In both directories (compiler support version wins, forwards)
+  module inttypes {
+    header "inttypes.h"
+  }
+
   // Only in system headers directory
   module stdio {
     header "stdio.h"
   }
 
   // In both directories (compiler support version wins, does not forward)
   module stdbool {
     header "stdbool.h"

clang/test/Modules/Werror-Wsystem-headers.m

 // RUN: rm -rf %t
 // RUN: rm -rf %t-saved
 // RUN: mkdir %t-saved
 
 // Initial module build
 // RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -fdisable-module-hash \
-// RUN:     -isystem %S/Inputs/System/usr/include -fsyntax-only %s -verify
+// RUN:     -internal-isystem %S/Inputs/System/usr/include -fsyntax-only %s -verify
 // RUN: cp %t/cstd.pcm %t-saved/cstd.pcm
 
 // Even with -Werror don't rebuild a system module
 // RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -fdisable-module-hash \
-// RUN:     -isystem %S/Inputs/System/usr/include -fsyntax-only %s -verify -Werror
+// RUN:     -internal-isystem %S/Inputs/System/usr/include -fsyntax-only %s -verify -Werror
 // RUN: diff %t/cstd.pcm %t-saved/cstd.pcm
 
 // Unless -Wsystem-headers is on
 // RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -fdisable-module-hash \
-// RUN:     -isystem %S/Inputs/System/usr/include -fsyntax-only %s -verify \
+// RUN:     -internal-isystem %S/Inputs/System/usr/include -fsyntax-only %s -verify \
 // RUN:     -Werror=unused -Wsystem-headers
 // RUN: not diff %t/cstd.pcm %t-saved/cstd.pcm
 
 // expected-no-diagnostics
 @import cstd;

clang/test/Modules/crash-vfs-include-pch.m

 // REQUIRES: crash-recovery, shell, system-darwin
 //
 // RUN: rm -rf %t
 // RUN: mkdir -p %t/m %t/out
 
 // RUN: %clang_cc1 -x objective-c-header -emit-pch %S/Inputs/pch-used.h \
 // RUN:     -o %t/out/pch-used.h.pch -fmodules -fimplicit-module-maps \
 // RUN:     -fmodules-cache-path=%t/cache -O0 \
-// RUN:     -isystem %S/Inputs/System/usr/include
+// RUN:     -internal-isystem %S/Inputs/System/usr/include
 
 // RUN: env FORCE_CLANG_DIAGNOSTICS_CRASH= TMPDIR=%t TEMP=%t TMP=%t \
 // RUN: not %clang %s -E -include-pch %t/out/pch-used.h.pch -fmodules -nostdlibinc \
 // RUN:     -fimplicit-module-maps -fmodules-cache-path=%t/cache -O0 \
-// RUN:     -Xclang -fno-validate-pch -isystem %S/Inputs/System/usr/include \
+// RUN:     -Xclang -fno-validate-pch -Xclang -internal-isystem -Xclang %S/Inputs/System/usr/include \
 // RUN:     -o %t/output.E 2>&1 | FileCheck %s
 
 // RUN: FileCheck --check-prefix=CHECKSH %s -input-file %t/crash-vfs-*.sh
 // RUN: FileCheck --check-prefix=CHECKYAML %s -input-file \
 // RUN:   %t/crash-vfs-*.cache/vfs/vfs.yaml
 
 void f() { SPXTrace(); }
 void g() { double x = DBL_MAX; }

clang/test/Modules/cstd.m

 
 // Supplied by the compiler; that version wins.
 @import cstd.stdbool;
 
 #ifndef bool
 #  error "bool was not defined!"
 #endif
 
+// Supplied by compiler, which forwards to the "/usr/include" version.
+@import cstd.inttypes;
+#ifndef __CLANG_INTTYPES_H
+#error "__CLANG_INTTYPES_H was not defined!"
+#endif
+#ifndef MY_PRIi32
+#error "MY_PRIi32 was not defined!"
+#endif

clang/test/Modules/pch-used.m

 // UNSUPPORTED: target={{.*}}-zos{{.*}}, target={{.*}}-aix{{.*}}
 // RUN: rm -rf %t
 // RUN: mkdir %t
-// RUN: %clang_cc1 -x objective-c-header -emit-pch %S/Inputs/pch-used.h -o %t/pch-used.h.pch -fmodules -fimplicit-module-maps -fmodules-cache-path=%t/cache -O0 -isystem %S/Inputs/System/usr/include
-// RUN: %clang_cc1 %s -include-pch %t/pch-used.h.pch -fmodules -fimplicit-module-maps -fmodules-cache-path=%t/cache -O0 -isystem %S/Inputs/System/usr/include -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 -x objective-c-header -emit-pch %S/Inputs/pch-used.h -o %t/pch-used.h.pch -fmodules -fimplicit-module-maps -fmodules-cache-path=%t/cache -O0 -internal-isystem %S/Inputs/System/usr/include
+// RUN: %clang_cc1 %s -include-pch %t/pch-used.h.pch -fmodules -fimplicit-module-maps -fmodules-cache-path=%t/cache -O0 -internal-isystem %S/Inputs/System/usr/include -emit-llvm -o - | FileCheck %s
 
 void f(void) { SPXTrace(); }
 void g(void) { double x = DBL_MAX; }
 
 // CHECK: define internal {{.*}}void @SPXTrace