Improve error reporting

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -290,7 +290,7 @@ impl<'a> DiagnosticHandlers<'a> {
         handler: &'a Handler,
         llcx: &'a llvm::Context,
         module: &ModuleCodegen<ModuleLlvm>,
-        section: CodegenDiagnosticsStage,
+        stage: CodegenDiagnosticsStage,
     ) -> Self {
         let remark_passes_all: bool;
         let remark_passes: Vec<CString>;
@@ -312,12 +312,12 @@ impl<'a> DiagnosticHandlers<'a> {
             .as_ref()
             // Use the .opt.yaml file suffix, which is supported by LLVM's opt-viewer.
             .map(|dir| {
-                let section = match section {
+                let stage_suffix = match stage {
                     CodegenDiagnosticsStage::Codegen => "codegen",
                     CodegenDiagnosticsStage::Opt => "opt",
                     CodegenDiagnosticsStage::LTO => "lto",
                 };
-                dir.join(format!("{}.{section}.opt.yaml", module.name))
+                dir.join(format!("{}.{stage_suffix}.opt.yaml", module.name))
             })
             .and_then(|dir| dir.to_str().and_then(|p| CString::new(p).ok()));
 

compiler/rustc_codegen_ssa/messages.ftl

@@ -21,6 +21,8 @@ codegen_ssa_create_temp_dir = couldn't create a temp dir: {$error}
 
 codegen_ssa_erroneous_constant = erroneous constant encountered
 
+codegen_ssa_error_creating_remark_dir = failed to create remark directory: {$error}
+
 codegen_ssa_expected_used_symbol = expected `used`, `used(compiler)` or `used(linker)`
 
 codegen_ssa_extern_funcs_not_found = some `extern` functions couldn't be found; some native libraries may need to be installed or have their path specified

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -35,6 +35,7 @@ use rustc_span::symbol::sym;
 use rustc_span::{BytePos, FileName, InnerSpan, Pos, Span};
 use rustc_target::spec::{MergeFunctions, SanitizerSet};
 
+use crate::errors::ErrorCreatingRemarkDir;
 use std::any::Any;
 use std::borrow::Cow;
 use std::fs;
@@ -1046,10 +1047,11 @@ fn start_executing_work<B: ExtraBackendMethods>(
     let backend_features = tcx.global_backend_features(());
 
     let remark_dir = if let Some(ref dir) = sess.opts.unstable_opts.remark_dir {
-        // Should this be here?
-        // Can this conflict with a parallel attempt to create this directory?
-        fs::create_dir_all(dir).expect("Cannot create remark directory");
-        Some(dir.canonicalize().expect("Cannot canonicalize remark directory"))
+        let result = fs::create_dir_all(dir).and_then(|_| dir.canonicalize());
+        match result {
+            Ok(dir) => Some(dir),
+            Err(error) => sess.emit_fatal(ErrorCreatingRemarkDir { error }),
+        }
     } else {
         None
     };

compiler/rustc_codegen_ssa/src/errors.rs

@@ -1023,3 +1023,9 @@ pub struct TargetFeatureSafeTrait {
     #[label(codegen_ssa_label_def)]
     pub def: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_error_creating_remark_dir)]
+pub struct ErrorCreatingRemarkDir {
+    pub error: std::io::Error,
+}

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -1877,17 +1877,17 @@ extern "C" void LLVMRustContextConfigureDiagnosticHandler(
       void *DiagnosticHandlerContext,
       bool RemarkAllPasses,
       std::vector<std::string> RemarkPasses,
+      std::unique_ptr<ToolOutputFile> RemarksFile,
       std::unique_ptr<llvm::remarks::RemarkStreamer> RemarkStreamer,
-      std::unique_ptr<LLVMRemarkStreamer> LlvmRemarkStreamer,
-      std::unique_ptr<ToolOutputFile> RemarksFile
+      std::unique_ptr<LLVMRemarkStreamer> LlvmRemarkStreamer
     )
         : DiagnosticHandlerCallback(DiagnosticHandlerCallback),
           DiagnosticHandlerContext(DiagnosticHandlerContext),
           RemarkAllPasses(RemarkAllPasses),
           RemarkPasses(std::move(RemarkPasses)),
+          RemarksFile(std::move(RemarksFile)),
           RemarkStreamer(std::move(RemarkStreamer)),
-          LlvmRemarkStreamer(std::move(LlvmRemarkStreamer)),
-          RemarksFile(std::move(RemarksFile)) {}
+          LlvmRemarkStreamer(std::move(LlvmRemarkStreamer)) {}
 
     virtual bool handleDiagnostics(const DiagnosticInfo &DI) override {
       if (this->LlvmRemarkStreamer) {
@@ -1939,11 +1939,11 @@ extern "C" void LLVMRustContextConfigureDiagnosticHandler(
     bool RemarkAllPasses = false;
     std::vector<std::string> RemarkPasses;
 
-    // Since LlvmRemarkStreamer contains a pointer to RemarkStreamer, the ordering of the two
+    // Since LlvmRemarkStreamer contains a pointer to RemarkStreamer, the ordering of the three
     // members below is important.
+    std::unique_ptr<ToolOutputFile> RemarksFile;
     std::unique_ptr<llvm::remarks::RemarkStreamer> RemarkStreamer;
     std::unique_ptr<LLVMRemarkStreamer> LlvmRemarkStreamer;
-    std::unique_ptr<ToolOutputFile> RemarksFile;
   };
 
   std::vector<std::string> Passes;
@@ -1953,9 +1953,9 @@ extern "C" void LLVMRustContextConfigureDiagnosticHandler(
   }
 
   // We need to hold onto both the streamers and the opened file
+  std::unique_ptr<ToolOutputFile> RemarkFile;
   std::unique_ptr<llvm::remarks::RemarkStreamer> RemarkStreamer;
   std::unique_ptr<LLVMRemarkStreamer> LlvmRemarkStreamer;
-  std::unique_ptr<ToolOutputFile> RemarkFile;
 
   if (RemarkFilePath != nullptr) {
     std::error_code EC;
@@ -1964,6 +1964,12 @@ extern "C" void LLVMRustContextConfigureDiagnosticHandler(
       EC,
       llvm::sys::fs::OF_TextWithCRLF
     );
+    if (EC) {
+      std::string Error = std::string("Cannot create remark file: ") +
+              toString(errorCodeToError(EC));
+      report_fatal_error(Twine(Error));
+    }
+
     // Do not delete the file after we gather remarks
     RemarkFile->keep();
 
@@ -1974,8 +1980,8 @@ extern "C" void LLVMRustContextConfigureDiagnosticHandler(
     );
     if (Error E = RemarkSerializer.takeError())
     {
-      // Is this OK?
-      report_fatal_error("Cannot create remark serializer");
+      std::string Error = std::string("Cannot create remark serializer: ") + toString(std::move(E));
+      report_fatal_error(Twine(Error));
     }
     RemarkStreamer = std::make_unique<llvm::remarks::RemarkStreamer>(std::move(*RemarkSerializer));
     LlvmRemarkStreamer = std::make_unique<LLVMRemarkStreamer>(*RemarkStreamer);
@@ -1986,9 +1992,9 @@ extern "C" void LLVMRustContextConfigureDiagnosticHandler(
     DiagnosticHandlerContext,
     RemarkAllPasses,
     Passes,
+    std::move(RemarkFile),
     std::move(RemarkStreamer),
-    std::move(LlvmRemarkStreamer),
-    std::move(RemarkFile)
+    std::move(LlvmRemarkStreamer)
   ));
 }