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Fix : Properly detect C runtime through target_feature cfg #725

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Fix : Properly detect C runtime through target_feature cfg #725

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5 changes: 1 addition & 4 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1491,10 +1491,7 @@ impl Build {
Some(true) => "-MT",
Some(false) => "-MD",
None => {
let features = self
.getenv("CARGO_CFG_TARGET_FEATURE")
.unwrap_or(String::new());
if features.contains("crt-static") {
if cfg!(target_feature = "crt-static") {
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There is a reason for why it's inappropriate to use cfg! here. Keyword is that it applies to the build script itself, not the compilation target.

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@elast0ny elast0ny Oct 3, 2022 •
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My tests with these changes were able to properly infer the C runtime based on the settings in my config.toml from the parent crate.

I thought the cc build script gets compiled during the build invocation of the parent crate which means the cgf! directive has access to the parent crate target_feature no ?

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The build script is compiled for the platform that executes the Rust compiler, but it doesn't necessarily mean that the compiler was asked to generate code for the same platform. Well, one can argue that *-windows-msvc binary code is generated only by *-windows-msvc toolchain, but formally speaking it's not safe assumption to make. And cc-rs doesn't make it.

"-MT"
} else {
"-MD"
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