[gcc/devel/rust/master] Fix ICE during HIR lowering of ExprWithBlock MatchExpr

[gcc/devel/rust/master] Fix ICE during HIR lowering of ExprWithBlock MatchExpr

[Thomas Schwinge]

https://gcc.gnu.org/g:5528001eca60bb115e6afc94105ecc7b3820eb52

commit 5528001eca60bb115e6afc94105ecc7b3820eb52
Author: Philip Herron <philip.herron@embecosm.com>
Date:   Tue Apr 19 12:40:39 2022 +0100

    Fix ICE during HIR lowering of ExprWithBlock MatchExpr
    
    When we are lowering blocks using the visitor pattern we must use the
    BaseClass of ExprWithBlock to abstract away the notion that this expr
    has a block such that we can handle cases like a block expr vs expressions
    with a block. This makes the usage of hir lowering of match expressions to
    be recursive, if we had more fine grained visitors in the AST we could fix
    these types of problems with compile time enforced interfaces.
    
    Fixes #858

Diff:
---
 gcc/rust/hir/rust-ast-lower-block.h             |  2 +
 gcc/rust/hir/rust-ast-lower-expr.h              | 47 +----------------------
 gcc/rust/hir/rust-ast-lower.cc                  | 51 +++++++++++++++++++++++++
 gcc/testsuite/rust/execute/torture/issue-858.rs | 32 ++++++++++++++++
 4 files changed, 86 insertions(+), 46 deletions(-)

diff --git a/gcc/rust/hir/rust-ast-lower-block.h b/gcc/rust/hir/rust-ast-lower-block.h
index b14668a78fd..512f4709c6d 100644
--- a/gcc/rust/hir/rust-ast-lower-block.h
+++ b/gcc/rust/hir/rust-ast-lower-block.h
@@ -191,6 +191,8 @@ public:
 
   void visit (AST::WhileLoopExpr &expr) override;
 
+  void visit (AST::MatchExpr &expr) override;
+
 private:
   ASTLoweringExprWithBlock ()
     : ASTLoweringBase (), translated (nullptr), terminated (false)
diff --git a/gcc/rust/hir/rust-ast-lower-expr.h b/gcc/rust/hir/rust-ast-lower-expr.h
index bb2507039d1..022002e18e2 100644
--- a/gcc/rust/hir/rust-ast-lower-expr.h
+++ b/gcc/rust/hir/rust-ast-lower-expr.h
@@ -674,52 +674,7 @@ public:
 
   void visit (AST::MatchExpr &expr) override
   {
-    HIR::Expr *branch_value
-      = ASTLoweringExpr::translate (expr.get_scrutinee_expr ().get ());
-
-    std::vector<HIR::MatchCase> match_arms;
-    for (auto &match_case : expr.get_match_cases ())
-      {
-	HIR::Expr *kase_expr
-	  = ASTLoweringExpr::translate (match_case.get_expr ().get ());
-
-	HIR::Expr *kase_guard_expr = nullptr;
-	if (match_case.get_arm ().has_match_arm_guard ())
-	  {
-	    kase_guard_expr = ASTLoweringExpr::translate (
-	      match_case.get_arm ().get_guard_expr ().get ());
-	  }
-
-	std::vector<std::unique_ptr<HIR::Pattern> > match_arm_patterns;
-	for (auto &pattern : match_case.get_arm ().get_patterns ())
-	  {
-	    HIR::Pattern *ptrn = ASTLoweringPattern::translate (pattern.get ());
-	    match_arm_patterns.push_back (std::unique_ptr<HIR::Pattern> (ptrn));
-	  }
-
-	HIR::MatchArm arm (std::move (match_arm_patterns), expr.get_locus (),
-			   std::unique_ptr<HIR::Expr> (kase_guard_expr),
-			   match_case.get_arm ().get_outer_attrs ());
-
-	auto crate_num = mappings->get_current_crate ();
-	Analysis::NodeMapping mapping (crate_num, expr.get_node_id (),
-				       mappings->get_next_hir_id (crate_num),
-				       UNKNOWN_LOCAL_DEFID);
-
-	HIR::MatchCase kase (std::move (mapping), std::move (arm),
-			     std::unique_ptr<HIR::Expr> (kase_expr));
-	match_arms.push_back (std::move (kase));
-      }
-
-    auto crate_num = mappings->get_current_crate ();
-    Analysis::NodeMapping mapping (crate_num, expr.get_node_id (),
-				   mappings->get_next_hir_id (crate_num),
-				   UNKNOWN_LOCAL_DEFID);
-
-    translated
-      = new HIR::MatchExpr (mapping, std::unique_ptr<HIR::Expr> (branch_value),
-			    std::move (match_arms), expr.get_inner_attrs (),
-			    expr.get_outer_attrs (), expr.get_locus ());
+    translated = ASTLoweringExprWithBlock::translate (&expr, &terminated);
   }
 
   void visit (AST::RangeFromToExpr &expr) override
diff --git a/gcc/rust/hir/rust-ast-lower.cc b/gcc/rust/hir/rust-ast-lower.cc
index 4a344c9f5ab..64c8f367102 100644
--- a/gcc/rust/hir/rust-ast-lower.cc
+++ b/gcc/rust/hir/rust-ast-lower.cc
@@ -299,6 +299,57 @@ ASTLoweringExprWithBlock::visit (AST::WhileLoopExpr &expr)
 			      expr.get_outer_attrs ());
 }
 
+void
+ASTLoweringExprWithBlock::visit (AST::MatchExpr &expr)
+{
+  HIR::Expr *branch_value
+    = ASTLoweringExpr::translate (expr.get_scrutinee_expr ().get ());
+
+  std::vector<HIR::MatchCase> match_arms;
+  for (auto &match_case : expr.get_match_cases ())
+    {
+      HIR::Expr *kase_expr
+	= ASTLoweringExpr::translate (match_case.get_expr ().get ());
+
+      HIR::Expr *kase_guard_expr = nullptr;
+      if (match_case.get_arm ().has_match_arm_guard ())
+	{
+	  kase_guard_expr = ASTLoweringExpr::translate (
+	    match_case.get_arm ().get_guard_expr ().get ());
+	}
+
+      std::vector<std::unique_ptr<HIR::Pattern> > match_arm_patterns;
+      for (auto &pattern : match_case.get_arm ().get_patterns ())
+	{
+	  HIR::Pattern *ptrn = ASTLoweringPattern::translate (pattern.get ());
+	  match_arm_patterns.push_back (std::unique_ptr<HIR::Pattern> (ptrn));
+	}
+
+      HIR::MatchArm arm (std::move (match_arm_patterns), expr.get_locus (),
+			 std::unique_ptr<HIR::Expr> (kase_guard_expr),
+			 match_case.get_arm ().get_outer_attrs ());
+
+      auto crate_num = mappings->get_current_crate ();
+      Analysis::NodeMapping mapping (crate_num, expr.get_node_id (),
+				     mappings->get_next_hir_id (crate_num),
+				     UNKNOWN_LOCAL_DEFID);
+
+      HIR::MatchCase kase (std::move (mapping), std::move (arm),
+			   std::unique_ptr<HIR::Expr> (kase_expr));
+      match_arms.push_back (std::move (kase));
+    }
+
+  auto crate_num = mappings->get_current_crate ();
+  Analysis::NodeMapping mapping (crate_num, expr.get_node_id (),
+				 mappings->get_next_hir_id (crate_num),
+				 UNKNOWN_LOCAL_DEFID);
+
+  translated
+    = new HIR::MatchExpr (mapping, std::unique_ptr<HIR::Expr> (branch_value),
+			  std::move (match_arms), expr.get_inner_attrs (),
+			  expr.get_outer_attrs (), expr.get_locus ());
+}
+
 // rust-ast-lower-expr.h
 
 void
diff --git a/gcc/testsuite/rust/execute/torture/issue-858.rs b/gcc/testsuite/rust/execute/torture/issue-858.rs
new file mode 100644
index 00000000000..5a43f3e1b1a
--- /dev/null
+++ b/gcc/testsuite/rust/execute/torture/issue-858.rs
@@ -0,0 +1,32 @@
+/* { dg-output "Result: 123\n" } */
+extern "C" {
+    fn printf(s: *const i8, ...);
+}
+
+enum Foo<T> {
+    A,
+    B(T),
+}
+
+fn main() -> i32 {
+    let result = Foo::B(123);
+
+    match result {
+        Foo::A => unsafe {
+            let a = "A\n\0";
+            let b = a as *const str;
+            let c = b as *const i8;
+
+            printf(c);
+        },
+        Foo::B(x) => unsafe {
+            let a = "Result: %i\n\0";
+            let b = a as *const str;
+            let c = b as *const i8;
+
+            printf(c, x);
+        },
+    }
+
+    0
+}