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rustc fails to link when the main function is inlined #47783

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Eijebong opened this issue Jan 26, 2018 · 1 comment
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rustc fails to link when the main function is inlined #47783

Eijebong opened this issue Jan 26, 2018 · 1 comment
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C-bug Category: This is a bug. I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️ T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@Eijebong
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This code fails to link:

#[inline(always)]
fn main() {}

with this nice linker error message

error: linking with `cc` failed: exit code: 1
  |
  = note: "cc" "-Wl,--as-needed" "-Wl,-z,noexecstack" "-m64" "-L" "/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib" "/playground/target/debug/deps/playground-b1780ebf501c82ef.playground0.rcgu.o" "-o" "/playground/target/debug/deps/playground-b1780ebf501c82ef" "/playground/target/debug/deps/playground-b1780ebf501c82ef.crate.allocator.rcgu.o" "-Wl,--gc-sections" "-pie" "-Wl,-z,relro,-z,now" "-nodefaultlibs" "-L" "/playground/target/debug/deps" "-L" "/playground/target/debug/build/backtrace-sys-65fded567eb95adc/out/.libs" "-L" "/playground/target/debug/build/miniz-sys-678f410ba3e047db/out" "-L" "/usr/lib/x86_64-linux-gnu" "-L" "/playground/target/debug/build/ring-c0358b5d62ddd508/out" "-L" "/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-Wl,-Bstatic" "/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libstd-58a9e2944951d97f.rlib" "/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/liballoc_jemalloc-17deae1aa65c9467.rlib" "/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libpanic_unwind-167b5e977a2ab35c.rlib" "/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libunwind-b8892ba833aa6677.rlib" "/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/liballoc_system-17235785be0fea01.rlib" "/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/liblibc-2e9b8cf09e3563de.rlib" "/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/liballoc-d7195d5e94bc6586.rlib" "/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libstd_unicode-963f18f265d9b8d3.rlib" "/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcore-48934815da5d2bfb.rlib" "/root/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler_builtins-a6b6fad6cc543169.rlib" "-Wl,-Bdynamic" "-l" "dl" "-l" "rt" "-l" "pthread" "-l" "pthread" "-l" "gcc_s" "-l" "c" "-l" "m" "-l" "rt" "-l" "pthread" "-l" "util" "-l" "util"
  = note: /usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/Scrt1.o: In function `_start':
          (.text+0x20): undefined reference to `main'
          collect2: error: ld returned 1 exit status
          

error: aborting due to previous error

error: Could not compile `playground`.

Here's a playground link: https://play.rust-lang.org/?gist=1b615b6d4160594fbb4e61b198de1dda&version=stable
@bluss bluss added the I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️ label Jan 26, 2018
@retep998
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Looks like a simple case of lazy inline function instantiation applying in a case where it shouldn't. The fix should be just marking the function as "used" for the sake of instantiating it.

cc @michaelwoerister

@cuviper cuviper added T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. C-bug Category: This is a bug. labels Jan 27, 2018
varkor added a commit to varkor/rust that referenced this issue Feb 25, 2018
@varkor
Ensure main() always has external linkage
2466644 
This ensures that the entry function is never elided due to inlining, even with `inline(always)`. Fixes rust-lang#47783.

There were a couple of possible ways of addressing this issue; I simply picked the one that seemed most direct. A warning could be appropriate, but considering using inlining hints in other places it doesn't apply also throws no warnings, and it seems like an edge case anyway, I haven't added one for now.
@varkor varkor mentioned this issue Feb 25, 2018
Merged
kennytm added a commit to kennytm/rust that referenced this issue Feb 27, 2018
@kennytm
Rollup merge of rust-lang#48541 - varkor:inlined-main, r=michaelwoeri…
8b3b254 
…ster

Ensure main() always has external linkage

This ensures that the entry function is never elided due to inlining, even with `inline(always)`. Fixes rust-lang#47783.

There were a couple of possible ways of addressing this issue; I simply picked the one that seemed most direct. A warning could be appropriate, but considering using inlining hints in other places it doesn't apply also throws no warnings, and it seems like an edge case anyway, I haven't added one for now.
kennytm added a commit to kennytm/rust that referenced this issue Feb 28, 2018
@kennytm
Rollup merge of rust-lang#48541 - varkor:inlined-main, r=michaelwoeri…
62f4fe5 
…ster

Ensure main() always has external linkage

This ensures that the entry function is never elided due to inlining, even with `inline(always)`. Fixes rust-lang#47783.

There were a couple of possible ways of addressing this issue; I simply picked the one that seemed most direct. A warning could be appropriate, but considering using inlining hints in other places it doesn't apply also throws no warnings, and it seems like an edge case anyway, I haven't added one for now.
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@cuviper @retep998 @bluss @Eijebong