clang: remove defer in bare blocks (#76)

Author: nalgeon

doc/spec.md

@@ -919,9 +919,7 @@ When `--track-source` is enabled, the reported source location may be off by a f
 
 ## Defer
 
-`defer` schedules a function or method call to run at the end of the enclosing scope.
-
-This scope can be either a function:
+`defer` schedules a function or method call to run at the end of the function:
 
 ```go
 func main() {
@@ -932,22 +930,9 @@ func main() {
 }
 ```
 
-Or a bare block:
-
-```go
-func example() {
-    {
-        xopen(&state)
-        defer xclose(&state)
-        // xclose(&state) runs here, at block end
-    }
-    // state is already closed here
-}
-```
-
-Deferred calls are emitted inline (before returns, panics, and scope end) in LIFO order. The return value is evaluated before the deferred calls run.
+Deferred calls are emitted inline (before returns, panics, and function end) in LIFO order. The return value is evaluated before the deferred calls run.
 
-Defer is not supported inside other scopes like `for` or `if`.
+Defer can only use variables declared at the top level of a function, not inside nested scopes like bare blocks, `for`, or `if`.
 
 ## C interop
 

internal/clang/visit.go

@@ -94,14 +94,8 @@ func (g *Generator) walkAST(w io.Writer, root ast.Node) {
 
 // emitBlockStmt emits a bare block statement (scoping block inside a function body).
 func (g *Generator) emitBlockStmt(w io.Writer, stmt *ast.BlockStmt) {
-	defers := g.state.defers // stash outer defers
-	g.state.defers = nil
 	fmt.Fprintf(w, "%s{\n", g.indent())
 	g.emitBlock(w, stmt)
-	g.state.indent++
-	g.emitDeferredCalls(w)
-	g.state.indent--
-	g.state.defers = defers // restore outer defers
 	fmt.Fprintf(w, "%s}\n", g.indent())
 }
 

testdata/lang/defer/dst/main.c

@@ -8,7 +8,6 @@ static so_int funcWithReturn(void);
 static so_R_int_err funcReturnCall(void);
 static so_int funcReturnVar(void);
 static so_R_int_err funcCalc(void);
-static void blockScope(void);
 
 // -- Variables and constants --
 static so_int state = 0;
@@ -64,31 +63,6 @@ static so_R_int_err funcCalc(void) {
     return (so_R_int_err){.val = 42, .err = (so_Error){0}};
 }
 
-static void blockScope(void) {
-    {
-        xopen(&state);
-        if (state != 1) {
-            xclose(&state);
-            so_panic("unexpected state");
-        }
-        xclose(&state);
-    }
-    if (state != 0) {
-        so_panic("unexpected state");
-    }
-    {
-        xopen(&state);
-        if (state != 1) {
-            xclose(&state);
-            so_panic("unexpected state");
-        }
-        xclose(&state);
-    }
-    if (state != 0) {
-        so_panic("unexpected state");
-    }
-}
-
 int main(void) {
     funcScope();
     if (state != 0) {
@@ -108,9 +82,5 @@ int main(void) {
     if (state != 0) {
         so_panic("unexpected state");
     }
-    blockScope();
-    if (state != 0) {
-        so_panic("unexpected state");
-    }
     return 0;
 }

testdata/lang/defer/src/main.go

@@ -47,29 +47,6 @@ func funcCalc() (int, error) {
 	return 42, nil
 }
 
-func blockScope() {
-	{
-		xopen(&state)
-		defer xclose(&state)
-		if state != 1 {
-			panic("unexpected state")
-		}
-	}
-	if state != 0 {
-		panic("unexpected state")
-	}
-	{
-		xopen(&state)
-		defer xclose(&state)
-		if state != 1 {
-			panic("unexpected state")
-		}
-	}
-	if state != 0 {
-		panic("unexpected state")
-	}
-}
-
 func main() {
 	funcScope()
 	if state != 0 {
@@ -89,8 +66,4 @@ func main() {
 	if state != 0 {
 		panic("unexpected state")
 	}
-	blockScope()
-	if state != 0 {
-		panic("unexpected state")
-	}
 }