FTBFS with llvm-14

[Andreas Hasenack]

postgresql-14 is failing to build[1] in jammy.

I see llvm-14 deprecation warnings:
In file included from /<<PKGBUILDDIR>>/build/../src/backend/jit/llvm/llvmjit.c:38:
/<<PKGBUILDDIR>>/build/../src/include/jit/llvmjit_emit.h: In function ‘l_load_struct_gep’:
/<<PKGBUILDDIR>>/build/../src/include/jit/llvmjit_emit.h:112:9: warning: ‘LLVMBuildStructGEP’ is deprecated [-Wdeprecated-declarations]
  112 | LLVMValueRef v_ptr = LLVMBuildStructGEP(b, v, idx, "");
      | ^~~~~~~~~~~~
In file included from /usr/lib/llvm-14/include/llvm-c/Core.h:18,
                 from /<<PKGBUILDDIR>>/build/../src/backend/jit/llvm/llvmjit.c:19:
/usr/lib/llvm-14/include/llvm-c/Core.h:3909:18: note: declared here
 3909 | LLVMValueRef LLVMBuildStructGEP(LLVMBuilderRef B, LLVMValueRef Pointer,
      | ^~~~~~~~~~~~~~~~~~
/usr/lib/llvm-14/include/llvm-c/Deprecated.h:29:3: note: in definition of macro ‘LLVM_ATTRIBUTE_C_DEPRECATED’
   29 | decl __attribute__((deprecated))
      | ^~~~
In file included from /<<PKGBUILDDIR>>/build/../src/backend/jit/llvm/llvmjit.c:38:
/<<PKGBUILDDIR>>/build/../src/include/jit/llvmjit_emit.h:114:9: warning: ‘LLVMBuildLoad’ is deprecated [-Wdeprecated-declarations]
  114 | return LLVMBuildLoad(b, v_ptr, name);
      | ^~~~~~

And the previous build[2] was using llvm-13.

But there are also some errors:
   28 | static std::new_handler old_new_handler = NULL;
      | ^~~~~~~~~~~
/<<PKGBUILDDIR>>/build/../src/backend/jit/llvm/llvmjit_error.cpp:32:64: error: ‘string’ in namespace ‘std’ does not name a type
   32 | static void fatal_llvm_new_handler(void *user_data, const std::string& reason, bool gen_crash_diag);
      | ^~~~~~
/<<PKGBUILDDIR>>/build/../src/backend/jit/llvm/llvmjit_error.cpp:25:1: note: ‘std::string’ is defined in header ‘<string>’; did you forget to ‘#include <string>’?
   24 | #include "jit/llvmjit.h"
  +++ |+#include <string>
   25 |

1. https://launchpadlibrarian.net/591985515/buildlog_ubuntu-jammy-amd64.postgresql-14_14.2-1_BUILDING.txt.gz
2. https://launchpadlibrarian.net/585392965/buildlog_ubuntu-jammy-amd64.postgresql-14_14.2-1_BUILDING.txt.gz

[Christian Ehrhardt  (paelzer)]

That llvm v14 is rather recent - we were lucky that llvm-13 worked fine.
Officially the most recent postgresql-release just added llvm-12 support [1].

In jammy we have:
 llvm-13 | 1:13.0.1-2ubuntu2 | jammy/universe | amd64, arm64, armhf, i386, ppc64el, riscv64, s390x
 llvm-14 | 1:14.0.0-1ubuntu1 | jammy-proposed/universe | amd64, arm64, armhf, i386, ppc64el, s390x

I can't see us transitioning completely to llvm-14 in time for jammy, so llvm-13 might stay as well? (ask Foundations please to be sure).
If it does stay, this might be as easy as putting a versioned build dep onto `llvm-dev` in d/control of postgresql-14.

On the other hand, maybe those are all just deprecation warnings and related follow on issues.
Having a test build with [2] might be worth a try.
Actually the REL_14_STABLE branch has a combined backport of this and other llvm-14 changes.
Those will be released with postgresql-14.3 some day, to fix it right now most likely the best shot would be [3]. And once 14.3 comes by we can drop our delta again.

[1]: https://www.postgresql.org/docs/14/release-14.html
[2]: https://github.com/postgres/postgres/commit/a56e7b66010f330782243de9e25ac2a6596be0e1
[3]: https://github.com/postgres/postgres/commit/d9f7ad54e552262ee0090e88d5abd3e04fcdeac8

[Andreas Hasenack (ahasenack)]

I tried a rebuild with llvm-13 to see if it would work, and if we have a plan B just in case, and it worked.

This was the patch, for reference:
diff --git a/debian/control b/debian/control
index 0d6c8636f3..f7d18ae093 100644
--- a/debian/control
+++ b/debian/control
@@ -11,7 +11,7 @@ Rules-Requires-Root: no
 Build-Depends:
  autoconf,
  bison,
- clang [!alpha !hppa !hurd-i386 !ia64 !kfreebsd-amd64 !kfreebsd-i386 !m68k !powerpc !riscv64 !s390x !sh4 !sparc64 !x32],
+ clang-13 [!alpha !hppa !hurd-i386 !ia64 !kfreebsd-amd64 !kfreebsd-i386 !m68k !powerpc !riscv64 !s390x !sh4 !sparc64 !x32],
  debhelper-compat (= 13),
  dh-exec (>= 0.13~),
  docbook-xml,
@@ -35,7 +35,7 @@ Build-Depends:
  libxml2-dev,
  libxml2-utils,
  libxslt1-dev,
- llvm-dev [!alpha !hppa !hurd-i386 !ia64 !kfreebsd-amd64 !kfreebsd-i386 !m68k !powerpc !riscv64 !s390x !sh4 !sparc64 !x32],
+ llvm-13-dev [!alpha !hppa !hurd-i386 !ia64 !kfreebsd-amd64 !kfreebsd-i386 !m68k !powerpc !riscv64 !s390x !sh4 !sparc64 !x32],
  mawk,
  perl (>= 5.8),
  pkg-config,

Now let's inspect those commits for llvm-14 and see how far I get

[Andreas Hasenack (ahasenack)]

Foundations confirmed llvm-13 will stay. Ok, on to plan A.

[Launchpad Janitor (janitor)]

This bug was fixed in the package postgresql-14 - 14.2-1ubuntu1

---------------
postgresql-14 (14.2-1ubuntu1) jammy; urgency=medium

  * d/p/llvm14-support.patch: fix FTBFS with llvm-14 (LP: #1966319)

 -- Andreas Hasenack <email address hidden> Fri, 25 Mar 2022 11:34:41 -0300