Special case DUMMY_SP to emit line 0/column 0 locations on DWARF platforms.

compiler/rustc_codegen_llvm/src/debuginfo/mod.rs

@@ -570,7 +570,17 @@ impl<'ll, 'tcx> DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
  inlined_at: Option<&'ll DILocation>,
  span: Span,
  ) -> &'ll DILocation {
- let DebugLoc { line, col, .. } = self.lookup_debug_loc(span.lo());
+ // When emitting debugging information, DWARF (i.e. everything but MSVC)
+ // treats line 0 as a magic value meaning that the code could not be
+ // attributed to any line in the source. That's also exactly what dummy
+ // spans are. Make that equivalence here, rather than passing dummy spans
+ // to lookup_debug_loc, which will return line 1 for them.
+ let (line, col) = if span.is_dummy() && !self.sess().target.is_like_msvc {
+ (0, 0)
+ } else {
+ let DebugLoc { line, col, .. } = self.lookup_debug_loc(span.lo());
+ (line, col)
+ };
 
  unsafe { llvm::LLVMRustDIBuilderCreateDebugLocation(line, col, scope, inlined_at) }
  }

tests/debuginfo/dummy_span.rs

@@ -0,0 +1,45 @@
+//@ min-lldb-version: 310
+
+//@ compile-flags:-g
+
+// === GDB TESTS ===================================================================================
+
+// gdb-command:run 7
+
+// gdb-command:next
+// gdb-command:next
+// gdb-check:[...]#loc1[...]
+// gdb-command:next
+// gdb-check:[...]#loc2[...]
+
+// === LLDB TESTS ==================================================================================
+
+// lldb-command:run 7
+
+// lldb-command:next
+// lldb-command:next
+// lldb-command:frame select
+// lldb-check:[...]#loc1[...]
+// lldb-command:next
+// lldb-command:frame select
+// lldb-check:[...]#loc2[...]
+
+use std::env;
+use std::num::ParseIntError;
+
+fn main() -> Result<(), ParseIntError> {
+ let args = env::args();
+ let number_str = args.skip(1).next().unwrap();
+ let number = number_str.parse::<i32>()?;
+ zzz(); // #break
+ if number % 7 == 0 {
+ // This generates code with a dummy span for
+ // some reason. If that ever changes this
+ // test will not test what it wants to test.
+ return Ok(()); // #loc1
+ }
+ println!("{}", number);
+ Ok(())
+} // #loc2
+
+fn zzz() { () }