read: Skip invalid ranges in RngListIter/LocListIter (#715)

I've encountered a toolchain which produces invalid ranges, where the
end of the range is before the beginning.

I want to fix that toolchain, of course, but I also noticed that tools
like `llvm-addr2line` and `llvm-dwarfdump --lookup` apparently silently
skip the invalid ranges, so they're able to give partial answers. By
contrast, `gimli` returns an error in this case. Then the `addr2line`
crate, for example, bubbles the error all the way out and doesn't return
any results.

The specific toolchain where I've encountered this is TinyGo (which uses
LLVM), when building WebAssembly with the `wasip1` target. I tested
TinyGo 0.32.0-dev and LLVM 17, and this was the shortest program I could
find which produces invalid ranges:
tinygo build -target=wasip1 /tmp/test.go
```go
package main
import "os"
func main() {
        os.Lstat("some-filename")
}
```

src/read/loclists.rs

@@ -650,15 +650,10 @@ impl<R: Reader> LocListIter<R> {
             }
         };
 
-        if range.begin == tombstone {
+        if range.begin == tombstone || range.begin > range.end {
             return Ok(None);
         }
 
-        if range.begin > range.end {
-            self.raw.input.empty();
-            return Err(Error::InvalidLocationAddressRange);
-        }
-
         Ok(Some(LocationListEntry { range, data }))
     }
 }
@@ -1522,7 +1517,7 @@ mod tests {
                 debug_addr_base,
             )
             .unwrap();
-        assert_eq!(locations.next(), Err(Error::InvalidLocationAddressRange));
+        assert_eq!(locations.next(), Ok(None));
 
         // An invalid location range after wrapping.
         let mut locations = loclists
@@ -1534,7 +1529,7 @@ mod tests {
                 debug_addr_base,
             )
             .unwrap();
-        assert_eq!(locations.next(), Err(Error::InvalidLocationAddressRange));
+        assert_eq!(locations.next(), Ok(None));
 
         // An invalid offset.
         match loclists.locations(

src/read/mod.rs

@@ -386,8 +386,6 @@ pub enum Error {
     UnknownCallFrameInstruction(constants::DwCfa),
     /// The end of an address range was before the beginning.
     InvalidAddressRange,
-    /// The end offset of a loc list entry was before the beginning.
-    InvalidLocationAddressRange,
     /// Encountered a call frame instruction in a context in which it is not
     /// valid.
     CfiInstructionInInvalidContext,
@@ -547,9 +545,6 @@ impl Error {
             Error::InvalidAddressRange => {
                 "The end of an address range must not be before the beginning."
             }
-            Error::InvalidLocationAddressRange => {
-                "The end offset of a location list entry must not be before the beginning."
-            }
             Error::CfiInstructionInInvalidContext => {
                 "Encountered a call frame instruction in a context in which it is not valid."
             }

src/read/rnglists.rs

@@ -569,15 +569,10 @@ impl<R: Reader> RngListIter<R> {
             }
         };
 
-        if range.begin == tombstone {
+        if range.begin == tombstone || range.begin > range.end {
             return Ok(None);
         }
 
-        if range.begin > range.end {
-            self.raw.input.empty();
-            return Err(Error::InvalidAddressRange);
-        }
-
         Ok(Some(range))
     }
 }
@@ -1402,7 +1397,7 @@ mod tests {
                 debug_addr_base,
             )
             .unwrap();
-        assert_eq!(ranges.next(), Err(Error::InvalidAddressRange));
+        assert_eq!(ranges.next(), Ok(None));
 
         // An invalid range after wrapping.
         let mut ranges = rnglists
@@ -1414,7 +1409,7 @@ mod tests {
                 debug_addr_base,
             )
             .unwrap();
-        assert_eq!(ranges.next(), Err(Error::InvalidAddressRange));
+        assert_eq!(ranges.next(), Ok(None));
 
         // An invalid offset.
         match rnglists.ranges(