std.debug.SelfInfo: concrete error sets

The downside of this commit is that more precise errors are no longer
propagated up. However, these errors were pretty useless in isolation
due to them having no context; and regardless, we intentionally swallow
most of them in `std.debug` anyway. Therefore, this is better in
practice, because it allows `std.debug` to give slightly more useful
warnings when handling errors. This commit does that for unwind errors,
for instance, which differentiate between the unwind info being corrupt
vs missing vs inaccessible vs unsupported.

A better solution would be to also include more detailed information via
the diagnostics pattern, but this commit is an incremental improvement.

1 files changed, 12 insertions, 7 deletions

diff --git a/lib/std/debug/SelfInfo/WindowsModule.zig b/lib/std/debug/SelfInfo/WindowsModule.zig
index 4f9d98353b..674c6adae5 100644
--- a/lib/std/debug/SelfInfo/WindowsModule.zig
+++ b/lib/std/debug/SelfInfo/WindowsModule.zig
@@ -5,7 +5,7 @@ handle: windows.HMODULE,
 pub fn key(m: WindowsModule) usize {
     return m.base_address;
 }
-pub fn lookup(cache: *LookupCache, gpa: Allocator, address: usize) !WindowsModule {
+pub fn lookup(cache: *LookupCache, gpa: Allocator, address: usize) std.debug.SelfInfo.Error!WindowsModule {
     if (lookupInCache(cache, address)) |m| return m;
     {
         // Check a new module hasn't been loaded
@@ -29,18 +29,23 @@ pub fn lookup(cache: *LookupCache, gpa: Allocator, address: usize) !WindowsModul
     if (lookupInCache(cache, address)) |m| return m;
     return error.MissingDebugInfo;
 }
-pub fn getSymbolAtAddress(module: *const WindowsModule, gpa: Allocator, di: *DebugInfo, address: usize) !std.debug.Symbol {
-    if (!di.loaded) try module.loadLocationInfo(gpa, di);
+pub fn getSymbolAtAddress(module: *const WindowsModule, gpa: Allocator, di: *DebugInfo, address: usize) std.debug.SelfInfo.Error!std.debug.Symbol {
+    if (!di.loaded) module.loadDebugInfo(gpa, di) catch |err| switch (err) {
+        error.OutOfMemory, error.InvalidDebugInfo, error.MissingDebugInfo, error.Unexpected => |e| return e,
+        error.FileNotFound => return error.MissingDebugInfo,
+        error.UnknownPDBVersion => return error.UnsupportedDebugInfo,
+        else => return error.ReadFailed,
+    };
     // Translate the runtime address into a virtual address into the module
     const vaddr = address - module.base_address;
 
     if (di.pdb != null) {
-        if (try di.getSymbolFromPdb(vaddr)) |symbol| return symbol;
+        if (di.getSymbolFromPdb(vaddr) catch return error.InvalidDebugInfo) |symbol| return symbol;
     }
 
     if (di.dwarf) |*dwarf| {
         const dwarf_address = vaddr + di.coff_image_base;
-        return dwarf.getSymbol(gpa, native_endian, dwarf_address);
+        return dwarf.getSymbol(gpa, native_endian, dwarf_address) catch return error.InvalidDebugInfo;
     }
 
     return error.MissingDebugInfo;
@@ -59,7 +64,7 @@ fn lookupInCache(cache: *const LookupCache, address: usize) ?WindowsModule {
     }
     return null;
 }
-fn loadLocationInfo(module: *const WindowsModule, gpa: Allocator, di: *DebugInfo) !void {
+fn loadDebugInfo(module: *const WindowsModule, gpa: Allocator, di: *DebugInfo) !void {
     const mapped_ptr: [*]const u8 = @ptrFromInt(module.base_address);
     const mapped = mapped_ptr[0..module.size];
     var coff_obj = coff.Coff.init(mapped, true) catch return error.InvalidDebugInfo;
@@ -151,7 +156,7 @@ fn loadLocationInfo(module: *const WindowsModule, gpa: Allocator, di: *DebugInfo
 
         di.pdb = Pdb.init(gpa, path) catch |err| switch (err) {
             error.FileNotFound, error.IsDir => break :pdb,
-            else => return err,
+            else => |e| return e,
         };
         try di.pdb.?.parseInfoStream();
         try di.pdb.?.parseDbiStream();