Switch SourceBuffer to diagnostics. (#3197)

This updates SourceBuffer to diagnostics. Some additional edits to
diagnostics were necessary due to issues moving arguments around, which
seems to stem from a compile error with clang 14 (fixed in later
versions).

---------

Co-authored-by: Richard Smith <richard@metafoo.co.uk>

toolchain/source/BUILD

@@ -12,6 +12,7 @@ cc_library(
     hdrs = ["source_buffer.h"],
     deps = [
         "//common:error",
+        "//toolchain/diagnostics:diagnostic_emitter",
         "@llvm-project//llvm:Support",
     ],
 )
@@ -24,6 +25,7 @@ cc_test(
         ":source_buffer",
         "//common:check",
         "//testing/base:gtest_main",
+        "//toolchain/diagnostics:diagnostic_emitter",
         "@com_google_googletest//:gtest",
         "@llvm-project//llvm:Support",
     ],

toolchain/source/source_buffer.cpp

@@ -10,36 +10,52 @@
 
 namespace Carbon {
 
+namespace {
+struct FilenameTranslator : DiagnosticLocationTranslator<llvm::StringRef> {
+  auto GetLocation(llvm::StringRef filename) -> DiagnosticLocation override {
+    return {.file_name = filename};
+  }
+};
+}  // namespace
+
 auto SourceBuffer::CreateFromFile(llvm::vfs::FileSystem& fs,
-                                  llvm::raw_ostream& error_stream,
-                                  llvm::StringRef filename)
+                                  llvm::StringRef filename,
+                                  DiagnosticConsumer& consumer)
     -> std::optional<SourceBuffer> {
+  FilenameTranslator translator;
+  DiagnosticEmitter<llvm::StringRef> emitter(translator, consumer);
+
   llvm::ErrorOr<std::unique_ptr<llvm::vfs::File>> file =
       fs.openFileForRead(filename);
   if (file.getError()) {
-    error_stream << "Error opening `" << filename
-                 << "`: " << file.getError().message();
+    CARBON_DIAGNOSTIC(ErrorOpeningFile, Error,
+                      "Error opening file for read: {0}", std::string);
+    emitter.Emit(filename, ErrorOpeningFile, file.getError().message());
     return std::nullopt;
   }
 
   llvm::ErrorOr<llvm::vfs::Status> status = (*file)->status();
   if (status.getError()) {
-    error_stream << "Error getting status for `" << filename
-                 << "`: " << file.getError().message();
+    CARBON_DIAGNOSTIC(ErrorStattingFile, Error, "Error statting file: {0}",
+                      std::string);
+    emitter.Emit(filename, ErrorStattingFile, file.getError().message());
     return std::nullopt;
   }
-  auto size = status->getSize();
+  int64_t size = status->getSize();
   if (size >= std::numeric_limits<int32_t>::max()) {
-    error_stream << "Cannot load `" << filename
-                 << "`: file is over the 2GiB input limit.";
+    CARBON_DIAGNOSTIC(FileTooLarge, Error,
+                      "File is over the 2GiB input limit; size is {0} bytes.",
+                      int64_t);
+    emitter.Emit(filename, FileTooLarge, size);
     return std::nullopt;
   }
 
   llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> buffer =
       (*file)->getBuffer(filename, size, /*RequiresNullTerminator=*/false);
   if (buffer.getError()) {
-    error_stream << "Error reading `" << filename
-                 << "`: " << file.getError().message();
+    CARBON_DIAGNOSTIC(ErrorReadingFile, Error, "Error reading file: {0}",
+                      std::string);
+    emitter.Emit(filename, ErrorReadingFile, file.getError().message());
     return std::nullopt;
   }
 

toolchain/source/source_buffer.h

@@ -11,6 +11,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/VirtualFileSystem.h"
+#include "toolchain/diagnostics/diagnostic_emitter.h"
 
 namespace Carbon {
 
@@ -35,10 +36,9 @@ class SourceBuffer {
  public:
   // Opens the requested file. Returns a SourceBuffer on success. Prints an
   // error and returns nullopt on failure.
-  // TODO: Switch to using diagnostics.
   static auto CreateFromFile(llvm::vfs::FileSystem& fs,
-                             llvm::raw_ostream& error_stream,
-                             llvm::StringRef filename)
+                             llvm::StringRef filename,
+                             DiagnosticConsumer& consumer)
       -> std::optional<SourceBuffer>;
 
   // Use one of the factory functions above to create a source buffer.

toolchain/source/source_buffer_test.cpp

@@ -8,6 +8,7 @@
 
 #include "common/check.h"
 #include "llvm/Support/VirtualFileSystem.h"
+#include "toolchain/diagnostics/diagnostic_emitter.h"
 
 namespace Carbon::Testing {
 namespace {
@@ -16,7 +17,8 @@ static constexpr llvm::StringLiteral TestFileName = "test.carbon";
 
 TEST(SourceBufferTest, MissingFile) {
   llvm::vfs::InMemoryFileSystem fs;
-  auto buffer = SourceBuffer::CreateFromFile(fs, llvm::errs(), TestFileName);
+  auto buffer = SourceBuffer::CreateFromFile(fs, TestFileName,
+                                             ConsoleDiagnosticConsumer());
   EXPECT_FALSE(buffer);
 }
 
@@ -25,7 +27,8 @@ TEST(SourceBufferTest, SimpleFile) {
   CARBON_CHECK(fs.addFile(TestFileName, /*ModificationTime=*/0,
                           llvm::MemoryBuffer::getMemBuffer("Hello World")));
 
-  auto buffer = SourceBuffer::CreateFromFile(fs, llvm::errs(), TestFileName);
+  auto buffer = SourceBuffer::CreateFromFile(fs, TestFileName,
+                                             ConsoleDiagnosticConsumer());
   ASSERT_TRUE(buffer);
 
   EXPECT_EQ(TestFileName, buffer->filename());
@@ -41,7 +44,8 @@ TEST(SourceBufferTest, NoNull) {
                                        /*BufferName=*/"",
                                        /*RequiresNullTerminator=*/false)));
 
-  auto buffer = SourceBuffer::CreateFromFile(fs, llvm::errs(), TestFileName);
+  auto buffer = SourceBuffer::CreateFromFile(fs, TestFileName,
+                                             ConsoleDiagnosticConsumer());
   ASSERT_TRUE(buffer);
 
   EXPECT_EQ(TestFileName, buffer->filename());
@@ -53,7 +57,8 @@ TEST(SourceBufferTest, EmptyFile) {
   CARBON_CHECK(fs.addFile(TestFileName, /*ModificationTime=*/0,
                           llvm::MemoryBuffer::getMemBuffer("")));
 
-  auto buffer = SourceBuffer::CreateFromFile(fs, llvm::errs(), TestFileName);
+  auto buffer = SourceBuffer::CreateFromFile(fs, TestFileName,
+                                             ConsoleDiagnosticConsumer());
   ASSERT_TRUE(buffer);
 
   EXPECT_EQ(TestFileName, buffer->filename());