feat(msvc-crt-static): add msvc-crt-static config for changing the de…

…fault

This is a very simplistic flag because in the future we need to do some more
principled/complex design work for dynamic vs static libc, and its relationship
to system dependencies and installers.

For now it's basically an escape hatch for people who want to roll the dice.

cargo-dist/src/config.rs

@@ -126,6 +126,13 @@ pub struct DistMetadata {
     #[serde(rename = "auto-includes")]
     pub auto_includes: Option<bool>,
 
+    /// Whether msvc targets should statically link the crt
+    ///
+    /// Defaults to true.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    #[serde(rename = "msvc-crt-static")]
+    pub msvc_crt_static: Option<bool>,
+
     /// The archive format to use for windows builds (defaults .zip)
     #[serde(skip_serializing_if = "Option::is_none")]
     #[serde(rename = "windows-archive")]
@@ -306,6 +313,7 @@ impl DistMetadata {
             pr_run_mode: _,
             allow_dirty: _,
             ssldotcom_windows_sign: _,
+            msvc_crt_static: _,
         } = self;
         if let Some(include) = include {
             for include in include {
@@ -349,6 +357,7 @@ impl DistMetadata {
             pr_run_mode,
             allow_dirty,
             ssldotcom_windows_sign,
+            msvc_crt_static,
         } = self;
 
         // Check for global settings on local packages
@@ -387,6 +396,9 @@ impl DistMetadata {
         if ssldotcom_windows_sign.is_some() {
             warn!("package.metadata.dist.ssldotcom-windows-sign is set, but this is only accepted in workspace.metadata (value is being ignored): {}", package_manifest_path);
         }
+        if msvc_crt_static.is_some() {
+            warn!("package.metadata.dist.msvc-crt-static is set, but this is only accepted in workspace.metadata (value is being ignored): {}", package_manifest_path);
+        }
 
         // Merge non-global settings
         if installers.is_none() {

cargo-dist/src/init.rs

@@ -223,6 +223,7 @@ fn get_new_dist_metadata(
             pr_run_mode: None,
             allow_dirty: None,
             ssldotcom_windows_sign: None,
+            msvc_crt_static: None,
         }
     };
 
@@ -740,6 +741,7 @@ fn apply_dist_to_metadata(metadata: &mut toml_edit::Item, meta: &DistMetadata) {
         pr_run_mode,
         allow_dirty,
         ssldotcom_windows_sign,
+        msvc_crt_static,
     } = &meta;
 
     apply_optional_value(
@@ -912,6 +914,13 @@ fn apply_dist_to_metadata(metadata: &mut toml_edit::Item, meta: &DistMetadata) {
         allow_dirty.as_ref(),
     );
 
+    apply_optional_value(
+        table,
+        "msvc-crt-static",
+        "Whether +crt-static should be used on msvc\n",
+        *msvc_crt_static,
+    );
+
     apply_optional_value(
         table,
         "ssldotcom-windows-sign",

cargo-dist/src/tasks.rs

@@ -209,6 +209,8 @@ pub struct DistGraph {
     pub publish_prereleases: bool,
     /// A GitHub repo to publish the Homebrew formula to
     pub tap: Option<String>,
+    /// Whether msvc targets should statically link the crt
+    pub msvc_crt_static: bool,
 }
 
 /// Various tools we have found installed on the system
@@ -663,11 +665,12 @@ impl<'pkg_graph> DistGraphBuilder<'pkg_graph> {
             publish_jobs: _,
             publish_prereleases,
             features,
-            default_features: no_default_features,
+            default_features,
             all_features,
             create_release,
             pr_run_mode: _,
             allow_dirty,
+            msvc_crt_static,
         } = &workspace_metadata;
 
         let desired_cargo_dist_version = cargo_dist_version.clone();
@@ -678,6 +681,7 @@ impl<'pkg_graph> DistGraphBuilder<'pkg_graph> {
         let merge_tasks = merge_tasks.unwrap_or(false);
         let fail_fast = fail_fast.unwrap_or(false);
         let create_release = create_release.unwrap_or(true);
+        let msvc_crt_static = msvc_crt_static.unwrap_or(true);
         let ssldotcom_windows_sign = ssldotcom_windows_sign.clone();
         let mut packages_with_mismatched_features = vec![];
         // Compute/merge package configs
@@ -693,7 +697,7 @@ impl<'pkg_graph> DistGraphBuilder<'pkg_graph> {
             // Only do workspace builds if all the packages agree with the workspace feature settings
             if &package_config.features != features
                 || &package_config.all_features != all_features
-                || &package_config.default_features != no_default_features
+                || &package_config.default_features != default_features
             {
                 packages_with_mismatched_features.push(package.name.clone());
             }
@@ -779,6 +783,7 @@ impl<'pkg_graph> DistGraphBuilder<'pkg_graph> {
                 user_publish_jobs,
                 publish_prereleases,
                 allow_dirty,
+                msvc_crt_static,
             },
             package_metadata,
             workspace_metadata,
@@ -1964,7 +1969,16 @@ impl<'pkg_graph> DistGraphBuilder<'pkg_graph> {
 
             // You're *supposed* to link libc statically on windows but Rust has a bad default.
             // See: https://rust-lang.github.io/rfcs/1721-crt-static.html
-            if target.contains("windows-msvc") {
+            //
+            // ... well ok it's actually more complicated than that. Most rust applications
+            // don't dynamically link anything non-trivial, so statically linking libc is fine.
+            // However if you need to dynamically link stuff there starts to be issues about
+            // agreeing to the crt in play. At that point you should ship a
+            // Visual C(++) Redistributable that installs the version of the runtime you depend
+            // on. Not doing that is basically rolling some dice and hoping the user already
+            // has it installed, which isn't great. We should support redists eventually,
+            // but for now this hacky global flag is here to let you roll dice.
+            if self.inner.msvc_crt_static && target.contains("windows-msvc") {
                 rustflags.push_str(" -Ctarget-feature=+crt-static");
             }