cover all parsed patterns with an error message

but, some invalid patterns are not parsed as expected. See https://github.com/rtfeldman/roc/issues/399

compiler/can/src/pattern.rs

@@ -175,14 +175,12 @@ pub fn canonicalize_pattern<'a>(
                 }
                 Ok(float) => Pattern::FloatLiteral(float),
             },
-            ptype @ DefExpr | ptype @ TopLevelDef | ptype @ FunctionArg => {
+            ptype => unsupported_pattern(env, ptype, region),
-                unsupported_pattern(env, ptype, region)
-            }
         },
 
         Underscore => match pattern_type {
             WhenBranch | FunctionArg => Pattern::Underscore,
-            ptype @ DefExpr | ptype @ TopLevelDef => unsupported_pattern(env, ptype, region),
+            ptype => unsupported_pattern(env, ptype, region),
         },
 
         NumLiteral(string) => match pattern_type {
@@ -193,9 +191,7 @@ pub fn canonicalize_pattern<'a>(
                 }
                 Ok(int) => Pattern::NumLiteral(var_store.fresh(), int),
             },
-            ptype @ DefExpr | ptype @ TopLevelDef | ptype @ FunctionArg => {
+            ptype => unsupported_pattern(env, ptype, region),
-                unsupported_pattern(env, ptype, region)
-            }
         },
 
         NonBase10Literal {
@@ -216,19 +212,20 @@ pub fn canonicalize_pattern<'a>(
                     }
                 }
             },
-            ptype @ DefExpr | ptype @ TopLevelDef | ptype @ FunctionArg => {
+            ptype => unsupported_pattern(env, ptype, region),
-                unsupported_pattern(env, ptype, region)
-            }
         },
 
-        StrLiteral(_string) => match pattern_type {
+        StrLiteral(string) => match pattern_type {
             WhenBranch => {
                 // TODO report whether string was malformed
                 Pattern::StrLiteral((*string).into())
             }
-            ptype @ DefExpr | ptype @ TopLevelDef | ptype @ FunctionArg => {
+            ptype => unsupported_pattern(env, ptype, region),
-                unsupported_pattern(env, ptype, region)
+        },
-            }
+
+        BlockStrLiteral(_lines) => match pattern_type {
+            WhenBranch => todo!("TODO block string literal pattern"),
+            ptype => unsupported_pattern(env, ptype, region),
         },
 
         SpaceBefore(sub_pattern, _) | SpaceAfter(sub_pattern, _) | Nested(sub_pattern) => {
@@ -296,7 +293,7 @@ pub fn canonicalize_pattern<'a>(
                             },
                         });
                     }
-                    _ => panic!("invalid pattern in record"),
+                    _ => unreachable!("Any other pattern should have given a parse error"),
                 }
             }
 
@@ -312,7 +309,15 @@ pub fn canonicalize_pattern<'a>(
             unreachable!("should have been handled in RecordDestructure");
         }
 
-        _ => panic!("TODO finish restoring can_pattern branch for {:?}", pattern),
+        Malformed(_str) => {
+            let problem = MalformedPatternProblem::Unknown;
+            malformed_pattern(env, problem, region)
+        }
+
+        QualifiedIdentifier { .. } => {
+            let problem = MalformedPatternProblem::QualifiedIdentifier;
+            malformed_pattern(env, problem, region)
+        }
     };
 
     Located {

compiler/problem/src/can.rs

@@ -92,7 +92,6 @@ pub enum RuntimeError {
     InvalidHex(std::num::ParseIntError, Box<str>),
     InvalidOctal(std::num::ParseIntError, Box<str>),
     InvalidBinary(std::num::ParseIntError, Box<str>),
-    QualifiedPatternIdent(InlinableString),
     CircularDef(Vec<Symbol>, Vec<(Region /* pattern */, Region /* expr */)>),
 
     /// When the author specifies a type annotation but no implementation
@@ -104,4 +103,6 @@ pub enum MalformedPatternProblem {
     MalformedInt,
     MalformedFloat,
     MalformedBase(Base),
+    Unknown,
+    QualifiedIdentifier,
 }

compiler/reporting/src/error/canonicalize.rs

@@ -343,20 +343,33 @@ fn pretty_runtime_error<'b>(
             use roc_problem::can::MalformedPatternProblem::*;
 
             let name = match problem {
-                MalformedInt => "integer",
+                MalformedInt => " integer ",
-                MalformedFloat => "float",
+                MalformedFloat => " float ",
-                MalformedBase(Base::Hex) => "hex integer",
+                MalformedBase(Base::Hex) => " hex integer ",
-                MalformedBase(Base::Binary) => "binary integer",
+                MalformedBase(Base::Binary) => " binary integer ",
-                MalformedBase(Base::Octal) => "octal integer",
+                MalformedBase(Base::Octal) => " octal integer ",
+                Unknown => " ",
+                QualifiedIdentifier => " qualified ",
+            };
+
+            let hint = match problem {
+                MalformedInt | MalformedFloat | MalformedBase(_) => alloc
+                    .hint()
+                    .append(alloc.reflow("Learn more about number literals at TODO")),
+                Unknown => alloc.nil(),
+                QualifiedIdentifier => alloc.hint().append(
+                    alloc.reflow("In patterns, only private and global tags can be qualified"),
+                ),
             };
 
             alloc.stack(vec![
                 alloc.concat(vec![
-                    alloc.reflow("This "),
+                    alloc.reflow("This"),
                     alloc.text(name),
-                    alloc.reflow(" pattern is malformed:"),
+                    alloc.reflow("pattern is malformed:"),
                 ]),
                 alloc.region(region),
+                hint,
             ])
         }
 

compiler/reporting/tests/test_reporting.rs

@@ -1486,6 +1486,8 @@ mod test_reporting {
 
                 2 ┆      100A -> 3
                   ┆      ^^^^
+
+                Hint: Learn more about number literals at TODO
                 "#
             ),
         )
@@ -1509,6 +1511,8 @@ mod test_reporting {
 
                 2 ┆      2.X -> 3
                   ┆      ^^^
+
+                Hint: Learn more about number literals at TODO
                 "#
             ),
         )
@@ -1532,6 +1536,8 @@ mod test_reporting {
 
                 2 ┆      0xZ -> 3
                   ┆      ^^^
+
+                Hint: Learn more about number literals at TODO
                 "#
             ),
         )
@@ -1555,6 +1561,8 @@ mod test_reporting {
 
                 2 ┆      0o9 -> 3
                   ┆      ^^^
+
+                Hint: Learn more about number literals at TODO
                 "#
             ),
         )
@@ -1578,6 +1586,8 @@ mod test_reporting {
 
                 2 ┆      0b4 -> 3
                   ┆      ^^^
+
+                Hint: Learn more about number literals at TODO
                 "#
             ),
         )