Commit 8f3ccbbe367bea66d7f0f364a957870eb2cc95a0 | zig

author	Matthew Lugg <mlugg@mlugg.co.uk> 2023-08-13 09:54:58+01:00
committer	Andrew Kelley <andrew@ziglang.org> 2023-08-14 11:43:21-07:00
log	8f3ccbbe367bea66d7f0f364a957870eb2cc95a0
tree	33dad0b953904d39e75490b05f414bdbc09869bb
parent	1054e67f01e0f2eff1adf4982189ebba0a3696ab

Sema: provide source location when analyzing panic handler

The panic handler decl_val was previously given a `unneeded` source
location, which was then added to the reference trace, resulting in a
crash if the source location was used in the reference trace. This
commit makes two trivial changes:

* Don't add unneeded source locations to the ref table (panic in debug, silently ignore in release)
* Pass a real source location when analyzing the panic handler

2 files changed, 27 insertions(+), 2 deletions(-)

src
- Sema.zig
test
- cases
  - compile_errors
    panic_has_source_location.zig

src/Sema.zig+10-2

 @@ -25202,7 +25202,7 @@ fn panicWithMsg(sema: *Sema, block: *Block, src: LazySrcLoc, msg_inst: Air.Inst.
     try sema.prepareSimplePanic(block);
     const panic_func = mod.funcInfo(mod.panic_func_index);
-    const panic_fn = try sema.analyzeDeclVal(block, .unneeded, panic_func.owner_decl);
+    const panic_fn = try sema.analyzeDeclVal(block, src, panic_func.owner_decl);
     const null_stack_trace = Air.internedToRef(mod.null_stack_trace);
     const opt_usize_ty = try mod.optionalType(.usize_type);
 @@ -30702,7 +30702,15 @@ fn addReferencedBy(
     src: LazySrcLoc,
     decl_index: Decl.Index,
 ) !void {
-    if (sema.mod.comp.reference_trace == @as(u32, 0)) return;
+    if (sema.mod.comp.reference_trace == 0) return;
+    if (src == .unneeded) {
+        // We can't use NeededSourceLocation, since sites handling that assume it means a compile
+        // error. Our long-term strategy here is to gradually transition from NeededSourceLocation
+        // into having more LazySrcLoc tags. In the meantime, let release compilers just ignore this
+        // reference (a slightly-incomplete error is better than a crash!), but trigger a panic in
+        // debug so we can fix this case.
+        if (std.debug.runtime_safety) unreachable else return;
+    }
     try sema.mod.reference_table.put(sema.gpa, decl_index, .{
         .referencer = block.src_decl,
         .src = src,

test/cases/compile_errors/panic_has_source_location.zig created+17

...	@@ -0,0 +1,17 @@
1	const std = @import("std");
2
3	export fn foo() void {
4	// This should appear in the reference trace
5	// (and definitely shouldn't crash due to an unneeded source location!)
6	@panic("oh no");
7	}
8
9	pub fn panic(_: []const u8, _: ?*std.builtin.StackTrace, _: ?usize) noreturn {
10	@compileError("panic");
11	}
12
13	// error
14	// backend=stage2
15	// target=native
16	//
17	// :10:5: error: panic