corrosion-rs · jschwe · Mar 27, 2022 · Mar 25, 2022 · Mar 25, 2022 · Mar 25, 2022
diff --git a/README.md b/README.md
@@ -183,6 +183,9 @@ That's equivalent to calling `cargo build --features chocolate vanilla`.
 It is also possible to specify the features as a target list property on the CMake target created
 by `corrosion_import_crate`. The property is called `CORROSION_FEATURES`.
 
+To disable linking against system libraries - appropiate when building `no_std` crates - use
+the `NO_STD` parameter for `corrosion_import_crate`.
+
 Finally, regarding features, cargo offers the ability to turn off default features or enable all
 features, with the `--all-features` and `--no-default-features` options. Corrosion offers corresponding
 parameters for `corrosion_import_crate` called `ALL_FEATURES` and `NO_DEFAULT_FEATURES`. The corresponding

diff --git a/cmake/Corrosion.cmake b/cmake/Corrosion.cmake
@@ -195,6 +195,9 @@ function(_add_cargo_build)
     if(COR_NO_DEFAULT_FEATURES)
         set(no_default_features_arg --no-default-features)
     endif()
+    if(COR_NO_STD)
+        set(no_default_libraries_arg --no-default-libraries)
+    endif()
 
     set(rustflags_target_property "$<TARGET_GENEX_EVAL:${target_name},$<TARGET_PROPERTY:${target_name},INTERFACE_CORROSION_RUSTFLAGS>>")
     # `rustflags_target_property` may contain multiple arguments and double quotes, so we _should_ single quote it to
@@ -290,6 +293,7 @@ function(_add_cargo_build)
                     ${features_args}
                     ${all_features_arg}
                     ${no_default_features_arg}
+                    ${no_default_libraries_arg}
                     ${features_genex}
                     ${cargo_target_option}
                     ${rustflags_genex}
@@ -321,7 +325,7 @@ function(_add_cargo_build)
 endfunction(_add_cargo_build)
 
 function(corrosion_import_crate)
-    set(OPTIONS ALL_FEATURES NO_DEFAULT_FEATURES)
+    set(OPTIONS ALL_FEATURES NO_DEFAULT_FEATURES NO_STD)
     set(ONE_VALUE_KEYWORDS MANIFEST_PATH PROFILE)
     set(MULTI_VALUE_KEYWORDS CRATES FEATURES)
     cmake_parse_arguments(COR "${OPTIONS}" "${ONE_VALUE_KEYWORDS}" "${MULTI_VALUE_KEYWORDS}" ${ARGN})

diff --git a/cmake/CorrosionGenerator.cmake b/cmake/CorrosionGenerator.cmake
@@ -39,32 +39,44 @@ function(_generator_parse_platform manifest version target)
     if(os STREQUAL "windows")
         set(is_windows TRUE)
 
-        list(APPEND libs "advapi32" "userenv" "ws2_32")
+        if(NOT COR_NO_STD)
+          list(APPEND libs "advapi32" "userenv" "ws2_32")
+        endif()
 
         if(env STREQUAL "msvc")
             set(is_windows_msvc TRUE)
 
-            list(APPEND libs_debug "msvcrtd")
-            list(APPEND libs_release "msvcrt")
+            if(NOT COR_NO_STD)
+              list(APPEND libs_debug "msvcrtd")
+              list(APPEND libs_release "msvcrt")
+            endif()
         elseif(env STREQUAL "gnu")
             set(is_windows_gnu TRUE)
 
-            list(APPEND libs "gcc_eh" "pthread")
+            if(NOT COR_NO_STD)
+              list(APPEND libs "gcc_eh" "pthread")
+            endif()
         endif()
 
-        if(version VERSION_LESS "1.33.0")
-            list(APPEND libs "shell32" "kernel32")
-        endif()
+        if(NOT COR_NO_STD)
+          if(version VERSION_LESS "1.33.0")
+              list(APPEND libs "shell32" "kernel32")
+          endif()
 
-        if(version VERSION_GREATER_EQUAL "1.57.0")
-            list(APPEND libs "bcrypt")
+          if(version VERSION_GREATER_EQUAL "1.57.0")
+              list(APPEND libs "bcrypt")
+          endif()
         endif()
     elseif(os STREQUAL "apple" AND env STREQUAL "darwin")
         set(is_macos TRUE)
 
-        list(APPEND libs "System" "resolv" "c" "m")
+        if(NOT COR_NO_STD)
+           list(APPEND libs "System" "resolv" "c" "m")
+        endif()
     elseif(os STREQUAL "linux")
-        list(APPEND libs "dl" "rt" "pthread" "gcc_s" "c" "m" "util")
+        if(NOT COR_NO_STD)
+           list(APPEND libs "dl" "rt" "pthread" "gcc_s" "c" "m" "util")
+        endif()
     endif()
 
     set_source_files_properties(

diff --git a/generator/src/subcommands/build_crate.rs b/generator/src/subcommands/build_crate.rs
@@ -15,6 +15,7 @@ const RUSTFLAGS: &str = "rustflags";
 const FEATURES: &str = "features";
 const ALL_FEATURES: &str = "all-features";
 const NO_DEFAULT_FEATURES: &str = "no-default-features";
+const NO_DEFAULT_LIBRARIES: &str = "no-default-libraries";
 
 pub fn subcommand() -> App<'static, 'static> {
     SubCommand::with_name(BUILD_CRATE)
@@ -24,7 +25,7 @@ pub fn subcommand() -> App<'static, 'static> {
                 .long("profile")
                 .takes_value(true)
                 .help("The cargo profile to build with, e.g. 'dev' or 'release'")
-                .conflicts_with(RELEASE)
+                .conflicts_with(RELEASE),
         )
         .arg(
             Arg::with_name(TARGET)
@@ -40,12 +41,13 @@ pub fn subcommand() -> App<'static, 'static> {
                 .required(true)
                 .help("The name of the package being built with cargo"),
         )
-        .arg(Arg::with_name(RUSTFLAGS)
-            .long(RUSTFLAGS)
-            .value_name("RUSTFLAGS")
-            .takes_value(true)
-            .multiple(false)
-            .help("The RUSTFLAGS to pass to rustc.")
+        .arg(
+            Arg::with_name(RUSTFLAGS)
+                .long(RUSTFLAGS)
+                .value_name("RUSTFLAGS")
+                .takes_value(true)
+                .multiple(false)
+                .help("The RUSTFLAGS to pass to rustc."),
         )
         .arg(
             Arg::with_name(FEATURES)
@@ -58,14 +60,19 @@ pub fn subcommand() -> App<'static, 'static> {
         )
         .arg(
             Arg::with_name(ALL_FEATURES)
-            .long(ALL_FEATURES)
+                .long(ALL_FEATURES)
                 .help("Specifies that all features of the crate are to be activated"),
         )
         .arg(
             Arg::with_name(NO_DEFAULT_FEATURES)
-            .long(NO_DEFAULT_FEATURES)
+                .long(NO_DEFAULT_FEATURES)
                 .help("Specifies that the default features of the crate are to be disabled"),
         )
+        .arg(
+            Arg::with_name(NO_DEFAULT_LIBRARIES)
+                .long(NO_DEFAULT_LIBRARIES)
+                .help("Disables linking against any default libraries"),
+        )
 }
 
 pub fn invoke(
@@ -124,7 +131,9 @@ pub fn invoke(
         .collect();
 
     if !languages.is_empty() {
-        rustflags += " -Cdefault-linker-libraries=yes";
+        if !matches.is_present(NO_DEFAULT_LIBRARIES) {
+            rustflags += " -Cdefault-linker-libraries=yes";
+        }
 
         // This loop gets the highest preference link language to use for the linker
         let mut highest_preference: Option<(Option<i32>, &str)> = None;
@@ -174,7 +183,11 @@ pub fn invoke(
 
         let rustflags_trimmed = rustflags.trim();
         if args.verbose {
-            println!("Rustflags for package {} are: `{}`", matches.value_of(PACKAGE).unwrap(), rustflags_trimmed);
+            println!(
+                "Rustflags for package {} are: `{}`",
+                matches.value_of(PACKAGE).unwrap(),
+                rustflags_trimmed
+            );
         }
         cargo.env("RUSTFLAGS", rustflags_trimmed);
     }

diff --git a/generator/src/subcommands/gen_cmake.rs b/generator/src/subcommands/gen_cmake.rs
@@ -6,8 +6,8 @@ use std::{
 };
 
 use clap::{App, Arg, ArgMatches, SubCommand};
-use semver::Version;
 use platforms::Platform;
+use semver::Version;
 
 mod platform;
 mod target;
@@ -24,6 +24,7 @@ const TARGET: &str = "target";
 const CARGO_VERSION: &str = "cargo-version";
 const PROFILE: &str = "profile";
 const CRATES: &str = "crates";
+const NO_DEFAULT_LIBRARIES: &str = "no-default-libraries";
 
 pub fn subcommand() -> App<'static, 'static> {
     SubCommand::with_name(GEN_CMAKE)
@@ -89,7 +90,7 @@ pub fn subcommand() -> App<'static, 'static> {
                 .long(PROFILE)
                 .value_name("PROFILE")
                 .required(false)
-                .help("Custom cargo profile to select.")
+                .help("Custom cargo profile to select."),
         )
         .arg(
             Arg::with_name(OUT_FILE)
@@ -98,6 +99,13 @@ pub fn subcommand() -> App<'static, 'static> {
                 .value_name("FILE")
                 .help("Output CMake file name. Defaults to stdout."),
         )
+        .arg(
+            Arg::with_name(NO_DEFAULT_LIBRARIES)
+                .long(NO_DEFAULT_LIBRARIES)
+                .help(
+                    "Do not include libraries usually included by default. Use for no-std crates",
+                ),
+        )
 }
 
 pub fn invoke(
@@ -183,11 +191,17 @@ cmake_minimum_required(VERSION 3.12)
         })
         .collect();
 
-    let cargo_profile =  matches.value_of(PROFILE);
+    let cargo_profile = matches.value_of(PROFILE);
 
     for target in &targets {
         target
-            .emit_cmake_target(&mut out_file, &cargo_platform, &cargo_version, cargo_profile)
+            .emit_cmake_target(
+                &mut out_file,
+                &cargo_platform,
+                &cargo_version,
+                cargo_profile,
+                !matches.is_present(NO_DEFAULT_LIBRARIES),
+            )
             .unwrap();
     }
 

diff --git a/generator/src/subcommands/gen_cmake/target.rs b/generator/src/subcommands/gen_cmake/target.rs
@@ -104,6 +104,7 @@ impl CargoTarget {
         platform: &super::platform::Platform,
         cargo_version: &semver::Version,
         cargo_profile: Option<&str>,
+        include_platform_libs: bool,
     ) -> Result<(), Box<dyn Error>> {
         // This bit aggregates the byproducts of "cargo build", which is needed for generators like Ninja.
         let mut byproducts = vec![];
@@ -172,10 +173,7 @@ _add_cargo_build(
 ",
             self.cargo_package.name,
             self.cargo_target.name,
-            self.cargo_package
-                .manifest_path
-                .as_str()
-                .replace("\\", "/"),
+            self.cargo_package.manifest_path.as_str().replace("\\", "/"),
             byproducts.join(" "),
             cargo_build_profile_option
         )?;
@@ -195,37 +193,39 @@ _add_cargo_build(
                         self.cargo_target.name
                     )?;
 
-                    if !platform.libs.is_empty() {
-                        writeln!(
-                            out_file,
-                            "set_property(TARGET {0}-static PROPERTY INTERFACE_LINK_LIBRARIES \
-                             {1})",
-                            self.cargo_target.name,
-                            platform.libs.join(" ")
-                        )?;
-                    }
-
-                    if !platform.libs_debug.is_empty() {
-                        writeln!(
-                            out_file,
-                            "set_property(TARGET {0}-static PROPERTY \
-                             INTERFACE_LINK_LIBRARIES_DEBUG {1})",
-                            self.cargo_target.name,
-                            platform.libs_debug.join(" ")
-                        )?;
-                    }
+                    if include_platform_libs {
+                        if !platform.libs.is_empty() {
+                            writeln!(
+                                out_file,
+                                "set_property(TARGET {0}-static PROPERTY INTERFACE_LINK_LIBRARIES \
+                                 {1})",
+                                self.cargo_target.name,
+                                platform.libs.join(" ")
+                            )?;
+                        }
 
-                    if !platform.libs_release.is_empty() {
-                        for config in &["RELEASE", "MINSIZEREL", "RELWITHDEBINFO"] {
+                        if !platform.libs_debug.is_empty() {
                             writeln!(
                                 out_file,
                                 "set_property(TARGET {0}-static PROPERTY \
-                                 INTERFACE_LINK_LIBRARIES_{2} {1})",
+                                 INTERFACE_LINK_LIBRARIES_DEBUG {1})",
                                 self.cargo_target.name,
-                                platform.libs_release.join(" "),
-                                config
+                                platform.libs_debug.join(" ")
                             )?;
                         }
+
+                        if !platform.libs_release.is_empty() {
+                            for config in &["RELEASE", "MINSIZEREL", "RELWITHDEBINFO"] {
+                                writeln!(
+                                    out_file,
+                                    "set_property(TARGET {0}-static PROPERTY \
+                                     INTERFACE_LINK_LIBRARIES_{2} {1})",
+                                    self.cargo_target.name,
+                                    platform.libs_release.join(" "),
+                                    config
+                                )?;
+                            }
+                        }
                     }
                 }
 

diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
@@ -18,6 +18,7 @@ add_subdirectory(cpp2rust)
 add_subdirectory(rust2cpp)
 add_subdirectory(workspace)
 add_subdirectory(rustflags)
+add_subdirectory(nostd)
 if (CMAKE_VERSION VERSION_GREATER_EQUAL 3.19.0)
     add_subdirectory(envvar)
     add_subdirectory(hostbuild)

diff --git a/test/nostd/CMakeLists.txt b/test/nostd/CMakeLists.txt
@@ -0,0 +1,7 @@
+corrosion_import_crate(MANIFEST_PATH rust/Cargo.toml NO_STD)
+
+set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -nostdlib")
+list(REMOVE_ITEM CMAKE_CXX_IMPLICIT_LINK_LIBRARIES stdc++)
+
+add_library(nostd-cpp-lib STATIC main.cpp)
+target_link_libraries(nostd-cpp-lib PUBLIC rust-nostd-lib)
diff --git a/test/nostd/main.cpp b/test/nostd/main.cpp
@@ -0,0 +1,6 @@
+extern "C" void rust_function();
+
+extern "C" void cpp_function() {
+    // Fail on linking issues
+    rust_function();
+}
diff --git a/test/nostd/rust/Cargo.lock b/test/nostd/rust/Cargo.lock
diff --git a/test/nostd/rust/Cargo.toml b/test/nostd/rust/Cargo.toml
@@ -0,0 +1,17 @@
+[package]
+name = "rust-nostd-lib"
+version = "0.1.0"
+edition = "2015"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+
+[lib]
+crate-type=["staticlib"]
+
+[profile.release]
+panic = "abort"
+
+[profile.dev]
+panic = "abort"
diff --git a/test/nostd/rust/src/lib.rs b/test/nostd/rust/src/lib.rs
@@ -0,0 +1,10 @@
+#![no_std]
+use core::panic::PanicInfo;
+
+#[no_mangle]
+pub extern "C" fn rust_function() {}
+
+#[panic_handler]
+fn panic(_panic: &PanicInfo<'_>) -> ! {
+    loop {}
+}