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6277d0e1

by Zubin Duggal at 2025-09-30T17:34:41+05:30

compiler: Warn when -finfo-table-map is used with -fllvm

These are currently not supported together.

Fixes #26435

@@ -3784,6 +3784,11 @@ makeDynFlagsConsistent dflags
                                   hostFullWays
          in dflags_c
 + | gopt Opt_InfoTableMap dflags
 + , LlvmCodeOutput <- backendCodeOutput (backend dflags)
 +    = loop (gopt_unset dflags Opt_InfoTableMap)
 +           "-finfo-table-map is incompatible with -fllvm"
++
   | otherwise = (dflags, mempty, mempty)
      where loc = mkGeneralSrcSpan (fsLit "when making flags consistent")
            loop updated_dflags warning

@@ -370,6 +370,11 @@ to a source location. This lookup table is generated by using the ``-finfo-table
      also want more precise information about constructor info tables then you
      should also use :ghc-flag:`-fdistinct-constructor-tables`.
 +    .. note::
 +        This flag is incompatible with :ghc-flag:`-fllvm`. If both flags are
 +        enabled, GHC will emit a warning and :ghc-flag:`-finfo-table-map` will
 +        have no effect.
++
      The :ghc-flag:`-finfo-table-map` flag will increase the binary size by quite
      a lot, depending on how big your project is. For compiling a project the
      size of GHC the overhead was about 200 megabytes.

 +main :: IO ()
 +main = putStrLn "hello world"
 \ No newline at end of file

 +when making flags consistent: warning: [GHC-74335] [-Winconsistent-flags (in -Wdefault)]
 +    -finfo-table-map is incompatible with -fllvm
++

@@ -331,3 +331,4 @@ test('T24839', [unless(arch('x86_64') or arch('aarch64'), skip), extra_files(["t
  test('t25150', [extra_files(["t25150"])], multimod_compile, ['Main.hs', '-v0 -working-dir t25150/dir a.c'])
  test('T25382', normal, makefile_test, [])
  test('T26018', req_c, makefile_test, [])
 +test('T26435', normal, compile, ['-finfo-table-map -fllvm'])