aaron.ballman created this revision.
aaron.ballman added reviewers: cor3ntin, erichkeane, rsmith.
aaron.ballman requested review of this revision.
Herald added a project: clang.
When we added support for `if consteval`, we accidentally formed a discarded
statement evaluation context for the branch-not-taken. However, a discarded
statement is a property of an `if constexpr` statement, not an `if consteval`
statement (https://eel.is/c++draft/stmt.if#2.sentence-2). This turned out to
cause issues when deducing the return type from a function with a consteval if
statement -- we wouldn't consider the branch-not-taken when deducing the return
type.
This fixes PR52206.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D112089
Files:
clang/lib/Parse/ParseStmt.cpp
clang/test/SemaCXX/cxx2b-consteval-if.cpp
Index: clang/test/SemaCXX/cxx2b-consteval-if.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/cxx2b-consteval-if.cpp
@@ -0,0 +1,43 @@
+// RUN: %clang_cc1 -std=c++2b -verify %s
+
+namespace PR52206 {
+constexpr auto f() {
+ if consteval { return 0; }
+ if !consteval { return 0.0; } // expected-error {{'auto' in return type
deduced as 'double' here but deduced as 'int' in earlier return statement}}
+}
+
+constexpr auto g() {
+ if !consteval { return 0; }
+ if consteval { return 0.0; } // expected-error {{'auto' in return type
deduced as 'double' here but deduced as 'int' in earlier return statement}}
+}
+
+constexpr auto h() {
+ if consteval { return 0; }
+ if !consteval { return 0; } // okay
+}
+
+constexpr auto i() {
+ if consteval {
+ if consteval { // expected-warning {{consteval if is always true in an
immediate context}}
+ return 1;
+ }
+ return 2;
+ } else {
+ return 1.0; // expected-error {{'auto' in return type deduced as 'double'
here but deduced as 'int' in earlier return statement}}
+ }
+}
+
+void test() {
+ auto x1 = f();
+ constexpr auto y1 = f();
+
+ auto x2 = g();
+ constexpr auto y2 = g();
+
+ auto x3 = h();
+ constexpr auto y3 = h();
+
+ auto x4 = i();
+ constexpr auto y4 = i();
+}
+} // namespace PR52206
Index: clang/lib/Parse/ParseStmt.cpp
===================================================================
--- clang/lib/Parse/ParseStmt.cpp
+++ clang/lib/Parse/ParseStmt.cpp
@@ -1441,12 +1441,13 @@
SourceLocation InnerStatementTrailingElseLoc;
StmtResult ThenStmt;
{
- bool ShouldEnter =
- (ConstexprCondition && !*ConstexprCondition) || IsConsteval;
+ bool ShouldEnter = ConstexprCondition && !*ConstexprCondition;
Sema::ExpressionEvaluationContext Context =
Sema::ExpressionEvaluationContext::DiscardedStatement;
- if (NotLocation.isInvalid() && IsConsteval)
+ if (NotLocation.isInvalid() && IsConsteval) {
Context = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ ShouldEnter = true;
+ }
EnterExpressionEvaluationContext PotentiallyDiscarded(
Actions, Context, nullptr,
@@ -1485,12 +1486,13 @@
Tok.is(tok::l_brace));
MisleadingIndentationChecker MIChecker(*this, MSK_else, ElseLoc);
- bool ShouldEnter =
- (ConstexprCondition && *ConstexprCondition) || IsConsteval;
+ bool ShouldEnter = ConstexprCondition && *ConstexprCondition;
Sema::ExpressionEvaluationContext Context =
Sema::ExpressionEvaluationContext::DiscardedStatement;
- if (NotLocation.isValid() && IsConsteval)
+ if (NotLocation.isValid() && IsConsteval) {
Context = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ ShouldEnter = true;
+ }
EnterExpressionEvaluationContext PotentiallyDiscarded(
Actions, Context, nullptr,
Index: clang/test/SemaCXX/cxx2b-consteval-if.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/cxx2b-consteval-if.cpp
@@ -0,0 +1,43 @@
+// RUN: %clang_cc1 -std=c++2b -verify %s
+
+namespace PR52206 {
+constexpr auto f() {
+ if consteval { return 0; }
+ if !consteval { return 0.0; } // expected-error {{'auto' in return type deduced as 'double' here but deduced as 'int' in earlier return statement}}
+}
+
+constexpr auto g() {
+ if !consteval { return 0; }
+ if consteval { return 0.0; } // expected-error {{'auto' in return type deduced as 'double' here but deduced as 'int' in earlier return statement}}
+}
+
+constexpr auto h() {
+ if consteval { return 0; }
+ if !consteval { return 0; } // okay
+}
+
+constexpr auto i() {
+ if consteval {
+ if consteval { // expected-warning {{consteval if is always true in an immediate context}}
+ return 1;
+ }
+ return 2;
+ } else {
+ return 1.0; // expected-error {{'auto' in return type deduced as 'double' here but deduced as 'int' in earlier return statement}}
+ }
+}
+
+void test() {
+ auto x1 = f();
+ constexpr auto y1 = f();
+
+ auto x2 = g();
+ constexpr auto y2 = g();
+
+ auto x3 = h();
+ constexpr auto y3 = h();
+
+ auto x4 = i();
+ constexpr auto y4 = i();
+}
+} // namespace PR52206
Index: clang/lib/Parse/ParseStmt.cpp
===================================================================
--- clang/lib/Parse/ParseStmt.cpp
+++ clang/lib/Parse/ParseStmt.cpp
@@ -1441,12 +1441,13 @@
SourceLocation InnerStatementTrailingElseLoc;
StmtResult ThenStmt;
{
- bool ShouldEnter =
- (ConstexprCondition && !*ConstexprCondition) || IsConsteval;
+ bool ShouldEnter = ConstexprCondition && !*ConstexprCondition;
Sema::ExpressionEvaluationContext Context =
Sema::ExpressionEvaluationContext::DiscardedStatement;
- if (NotLocation.isInvalid() && IsConsteval)
+ if (NotLocation.isInvalid() && IsConsteval) {
Context = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ ShouldEnter = true;
+ }
EnterExpressionEvaluationContext PotentiallyDiscarded(
Actions, Context, nullptr,
@@ -1485,12 +1486,13 @@
Tok.is(tok::l_brace));
MisleadingIndentationChecker MIChecker(*this, MSK_else, ElseLoc);
- bool ShouldEnter =
- (ConstexprCondition && *ConstexprCondition) || IsConsteval;
+ bool ShouldEnter = ConstexprCondition && *ConstexprCondition;
Sema::ExpressionEvaluationContext Context =
Sema::ExpressionEvaluationContext::DiscardedStatement;
- if (NotLocation.isValid() && IsConsteval)
+ if (NotLocation.isValid() && IsConsteval) {
Context = Sema::ExpressionEvaluationContext::ImmediateFunctionContext;
+ ShouldEnter = true;
+ }
EnterExpressionEvaluationContext PotentiallyDiscarded(
Actions, Context, nullptr,
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