Improve syntax error reporting by including source file names

jjtolton · claude · jjtolton · commit f9ec456a572c · 2025-10-21T23:38:26.000-04:00
When syntax errors occur during file loading, the error messages now include the actual source file name and line number instead of just showing the predicate name where the error was caught. Before: error(syntax_error(incomplete_reduction),read_term/3:10). After: error(syntax_error(incomplete_reduction),'test_file.pl':8). Changes: - Added file_name field to MachineError struct to track source files - Updated error_form() to include file names in error context when available - Modified read_term() error handling to extract and set file names from streams - Added set_file_name() method for proper encapsulation This significantly improves debugging experience, especially when loading multiple files, as developers can immediately identify which file contains the syntax error. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
diff --git a/src/machine/machine_errors.rs b/src/machine/machine_errors.rs
@@ -20,6 +20,14 @@ pub type MachineStubGen = Box<dyn Fn(&mut MachineState) -> MachineStub>;
 pub(crate) struct MachineError {
     stub: MachineStub,
     location: Option<(usize, usize)>, // line_num, col_num
+    file_name: Option<Atom>, // source file name if available
+}
+
+impl MachineError {
+    #[inline]
+    pub(crate) fn set_file_name(&mut self, file_name: Option<Atom>) {
+        self.file_name = file_name;
+    }
 }
 
 // from 7.12.2 b) of 13211-1:1995
@@ -93,6 +101,7 @@ impl TypeError for HeapCellValue {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 }
@@ -107,6 +116,7 @@ impl TypeError for MachineStub {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 }
@@ -124,6 +134,7 @@ impl TypeError for Number {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 }
@@ -156,6 +167,7 @@ impl PermissionError for Atom {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 }
@@ -199,6 +211,7 @@ impl PermissionError for HeapCellValue {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 }
@@ -222,6 +235,7 @@ impl PermissionError for MachineStub {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 }
@@ -240,6 +254,7 @@ impl DomainError for HeapCellValue {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 }
@@ -257,6 +272,7 @@ impl DomainError for Number {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 }
@@ -271,6 +287,7 @@ impl DomainError for MachineStub {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 }
@@ -292,6 +309,7 @@ impl DomainError for ffi::Value {
                 MachineError {
                     stub,
                     location: None,
+                    file_name: None,
                 }
             }
             Value::Struct(atom, _values) => atom_as_cell!(atom).domain_error(machine_st, error),
@@ -312,6 +330,7 @@ impl MachineState {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 
@@ -324,6 +343,7 @@ impl MachineState {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 
@@ -346,6 +366,7 @@ impl MachineState {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 
@@ -368,6 +389,7 @@ impl MachineState {
                 MachineError {
                     stub,
                     location: None,
+                    file_name: None,
                 }
             }
             ExistenceError::QualifiedProcedure {
@@ -386,6 +408,7 @@ impl MachineState {
                 MachineError {
                     stub,
                     location: None,
+                    file_name: None,
                 }
             }
             ExistenceError::Procedure(name, arity) => {
@@ -399,6 +422,7 @@ impl MachineState {
                 MachineError {
                     stub,
                     location: None,
+                    file_name: None,
                 }
             }
             ExistenceError::ModuleSource(source) => {
@@ -412,6 +436,7 @@ impl MachineState {
                 MachineError {
                     stub,
                     location: None,
+                    file_name: None,
                 }
             }
             ExistenceError::SourceSink(culprit) => {
@@ -423,6 +448,7 @@ impl MachineState {
                 MachineError {
                     stub,
                     location: None,
+                    file_name: None,
                 }
             }
             ExistenceError::Stream(culprit) => {
@@ -434,6 +460,7 @@ impl MachineState {
                 MachineError {
                     stub,
                     location: None,
+                    file_name: None,
                 }
             }
             ExistenceError::Process(culprit) => {
@@ -445,6 +472,7 @@ impl MachineState {
                 MachineError {
                     stub,
                     location: None,
+                    file_name: None,
                 }
             }
             ExistenceError::FfiFunction(name, arity) => {
@@ -457,6 +485,7 @@ impl MachineState {
                 MachineError {
                     stub,
                     location: None,
+                    file_name: None,
                 }
             }
             ExistenceError::FfiStructConstructor(name, arity) => {
@@ -472,6 +501,7 @@ impl MachineState {
                 MachineError {
                     stub,
                     location: None,
+                    file_name: None,
                 }
             }
             ExistenceError::FfiStructType(atom) => {
@@ -483,6 +513,7 @@ impl MachineState {
                 MachineError {
                     stub,
                     location: None,
+                    file_name: None,
                 }
             }
         }
@@ -563,6 +594,7 @@ impl MachineState {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 
@@ -650,7 +682,11 @@ impl MachineState {
 
         let stub = functor!(atom!("syntax_error"), [functor(stub)]);
 
-        MachineError { stub, location }
+        MachineError {
+            stub,
+            location,
+            file_name: None,
+        }
     }
 
     pub(super) fn representation_error(&self, flag: RepFlag) -> MachineError {
@@ -662,6 +698,7 @@ impl MachineState {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 
@@ -677,6 +714,7 @@ impl MachineState {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 
@@ -686,6 +724,7 @@ impl MachineState {
         MachineError {
             stub,
             location: None,
+            file_name: None,
         }
     }
 
@@ -701,6 +740,7 @@ impl MachineState {
                 MachineError {
                     stub,
                     location: None,
+                    file_name: None,
                 }
             }
             FfiError::ValueOutOfRange(domain, culprit) => self.domain_error(domain, culprit),
@@ -726,6 +766,7 @@ impl MachineState {
             FfiError::AllocationFailed => MachineError {
                 stub: functor!(atom!("resource_error"), [atom_as_cell((atom!("heap")))]),
                 location: None,
+                file_name: None,
             },
             FfiError::LayoutError => self.representation_error(RepFlag::FfiLayout),
             FfiError::UnsupportedTypedef => self.representation_error(RepFlag::FfiLayout),
@@ -747,16 +788,32 @@ impl MachineState {
 
     pub(super) fn error_form(&mut self, err: MachineError, src: MachineStub) -> MachineStub {
         if let Some((line_num, _col_num)) = err.location {
-            functor!(
-                atom!("error"),
-                [
-                    functor((err.stub)),
-                    functor(
-                        (atom!(":")),
-                        [functor(src), number(line_num, (&mut self.arena))]
-                    )
-                ]
-            )
+            // Include file name in error if available
+            if let Some(file_name) = err.file_name {
+                let file_cell = atom_as_cell!(file_name);
+
+                functor!(
+                    atom!("error"),
+                    [
+                        functor((err.stub)),
+                        functor(
+                            (atom!(":")),
+                            [cell(file_cell), number(line_num, (&mut self.arena))]
+                        )
+                    ]
+                )
+            } else {
+                functor!(
+                    atom!("error"),
+                    [
+                        functor((err.stub)),
+                        functor(
+                            (atom!(":")),
+                            [functor(src), number(line_num, (&mut self.arena))]
+                        )
+                    ]
+                )
+            }
         } else {
             functor!(atom!("error"), [functor((err.stub)), functor(src)])
         }
diff --git a/src/machine/machine_state.rs b/src/machine/machine_state.rs
@@ -843,7 +843,9 @@ impl MachineState {
                     }
 
                     let stub = functor_stub(atom!("read_term"), 3);
-                    let err = self.syntax_error(err);
+                    let mut err = self.syntax_error(err);
+                    // Add file name to error if available
+                    err.set_file_name(stream.file_name());
 
                     return Err(self.error_form(err, stub));
                 }

Original file line number	Diff line number	Diff line change
`@@ -20,6 +20,14 @@ pub type MachineStubGen = Box<dyn Fn(&mut MachineState) -> MachineStub>;`
`20`	`20`	`pub(crate) struct MachineError {`
`21`	`21`	`stub: MachineStub,`
`22`	`22`	`location: Option<(usize, usize)>, // line_num, col_num`
	`23`	`+ file_name: Option<Atom>, // source file name if available`
	`24`	`+}`
	`25`	`+`
	`26`	`+impl MachineError {`
	`27`	`+ #[inline]`
	`28`	`+ pub(crate) fn set_file_name(&mut self, file_name: Option<Atom>) {`
	`29`	`+ self.file_name = file_name;`
	`30`	`+ }`
`23`	`31`	`}`
`24`	`32`
`25`	`33`	`// from 7.12.2 b) of 13211-1:1995`
`@@ -93,6 +101,7 @@ impl TypeError for HeapCellValue {`
`93`	`101`	`MachineError {`
`94`	`102`	`stub,`
`95`	`103`	`location: None,`
	`104`	`+ file_name: None,`
`96`	`105`	`}`
`97`	`106`	`}`
`98`	`107`	`}`
`@@ -107,6 +116,7 @@ impl TypeError for MachineStub {`
`107`	`116`	`MachineError {`
`108`	`117`	`stub,`
`109`	`118`	`location: None,`
	`119`	`+ file_name: None,`
`110`	`120`	`}`
`111`	`121`	`}`
`112`	`122`	`}`
`@@ -124,6 +134,7 @@ impl TypeError for Number {`
`124`	`134`	`MachineError {`
`125`	`135`	`stub,`
`126`	`136`	`location: None,`
	`137`	`+ file_name: None,`
`127`	`138`	`}`
`128`	`139`	`}`
`129`	`140`	`}`
`@@ -156,6 +167,7 @@ impl PermissionError for Atom {`
`156`	`167`	`MachineError {`
`157`	`168`	`stub,`
`158`	`169`	`location: None,`
	`170`	`+ file_name: None,`
`159`	`171`	`}`
`160`	`172`	`}`
`161`	`173`	`}`
`@@ -199,6 +211,7 @@ impl PermissionError for HeapCellValue {`
`199`	`211`	`MachineError {`
`200`	`212`	`stub,`
`201`	`213`	`location: None,`
	`214`	`+ file_name: None,`
`202`	`215`	`}`
`203`	`216`	`}`
`204`	`217`	`}`
`@@ -222,6 +235,7 @@ impl PermissionError for MachineStub {`
`222`	`235`	`MachineError {`
`223`	`236`	`stub,`
`224`	`237`	`location: None,`
	`238`	`+ file_name: None,`
`225`	`239`	`}`
`226`	`240`	`}`
`227`	`241`	`}`
`@@ -240,6 +254,7 @@ impl DomainError for HeapCellValue {`
`240`	`254`	`MachineError {`
`241`	`255`	`stub,`
`242`	`256`	`location: None,`
	`257`	`+ file_name: None,`
`243`	`258`	`}`
`244`	`259`	`}`
`245`	`260`	`}`
`@@ -257,6 +272,7 @@ impl DomainError for Number {`
`257`	`272`	`MachineError {`
`258`	`273`	`stub,`
`259`	`274`	`location: None,`
	`275`	`+ file_name: None,`
`260`	`276`	`}`
`261`	`277`	`}`
`262`	`278`	`}`
`@@ -271,6 +287,7 @@ impl DomainError for MachineStub {`
`271`	`287`	`MachineError {`
`272`	`288`	`stub,`
`273`	`289`	`location: None,`
	`290`	`+ file_name: None,`
`274`	`291`	`}`
`275`	`292`	`}`
`276`	`293`	`}`
`@@ -292,6 +309,7 @@ impl DomainError for ffi::Value {`
`292`	`309`	`MachineError {`
`293`	`310`	`stub,`
`294`	`311`	`location: None,`
	`312`	`+ file_name: None,`
`295`	`313`	`}`
`296`	`314`	`}`
`297`	`315`	`Value::Struct(atom, _values) => atom_as_cell!(atom).domain_error(machine_st, error),`
`@@ -312,6 +330,7 @@ impl MachineState {`
`312`	`330`	`MachineError {`
`313`	`331`	`stub,`
`314`	`332`	`location: None,`
	`333`	`+ file_name: None,`
`315`	`334`	`}`
`316`	`335`	`}`
`317`	`336`
`@@ -324,6 +343,7 @@ impl MachineState {`
`324`	`343`	`MachineError {`
`325`	`344`	`stub,`
`326`	`345`	`location: None,`
	`346`	`+ file_name: None,`
`327`	`347`	`}`
`328`	`348`	`}`
`329`	`349`
`@@ -346,6 +366,7 @@ impl MachineState {`
`346`	`366`	`MachineError {`
`347`	`367`	`stub,`
`348`	`368`	`location: None,`
	`369`	`+ file_name: None,`
`349`	`370`	`}`
`350`	`371`	`}`
`351`	`372`
`@@ -368,6 +389,7 @@ impl MachineState {`
`368`	`389`	`MachineError {`
`369`	`390`	`stub,`
`370`	`391`	`location: None,`
	`392`	`+ file_name: None,`
`371`	`393`	`}`
`372`	`394`	`}`
`373`	`395`	`ExistenceError::QualifiedProcedure {`
`@@ -386,6 +408,7 @@ impl MachineState {`
`386`	`408`	`MachineError {`
`387`	`409`	`stub,`
`388`	`410`	`location: None,`
	`411`	`+ file_name: None,`
`389`	`412`	`}`
`390`	`413`	`}`
`391`	`414`	`ExistenceError::Procedure(name, arity) => {`
`@@ -399,6 +422,7 @@ impl MachineState {`
`399`	`422`	`MachineError {`
`400`	`423`	`stub,`
`401`	`424`	`location: None,`
	`425`	`+ file_name: None,`
`402`	`426`	`}`
`403`	`427`	`}`
`404`	`428`	`ExistenceError::ModuleSource(source) => {`
`@@ -412,6 +436,7 @@ impl MachineState {`
`412`	`436`	`MachineError {`
`413`	`437`	`stub,`
`414`	`438`	`location: None,`
	`439`	`+ file_name: None,`
`415`	`440`	`}`
`416`	`441`	`}`
`417`	`442`	`ExistenceError::SourceSink(culprit) => {`
`@@ -423,6 +448,7 @@ impl MachineState {`
`423`	`448`	`MachineError {`
`424`	`449`	`stub,`
`425`	`450`	`location: None,`
	`451`	`+ file_name: None,`
`426`	`452`	`}`
`427`	`453`	`}`
`428`	`454`	`ExistenceError::Stream(culprit) => {`
`@@ -434,6 +460,7 @@ impl MachineState {`
`434`	`460`	`MachineError {`
`435`	`461`	`stub,`
`436`	`462`	`location: None,`
	`463`	`+ file_name: None,`
`437`	`464`	`}`
`438`	`465`	`}`
`439`	`466`	`ExistenceError::Process(culprit) => {`
`@@ -445,6 +472,7 @@ impl MachineState {`
`445`	`472`	`MachineError {`
`446`	`473`	`stub,`
`447`	`474`	`location: None,`
	`475`	`+ file_name: None,`
`448`	`476`	`}`
`449`	`477`	`}`
`450`	`478`	`ExistenceError::FfiFunction(name, arity) => {`
`@@ -457,6 +485,7 @@ impl MachineState {`
`457`	`485`	`MachineError {`
`458`	`486`	`stub,`
`459`	`487`	`location: None,`
	`488`	`+ file_name: None,`
`460`	`489`	`}`
`461`	`490`	`}`
`462`	`491`	`ExistenceError::FfiStructConstructor(name, arity) => {`
`@@ -472,6 +501,7 @@ impl MachineState {`
`472`	`501`	`MachineError {`
`473`	`502`	`stub,`
`474`	`503`	`location: None,`
	`504`	`+ file_name: None,`
`475`	`505`	`}`
`476`	`506`	`}`
`477`	`507`	`ExistenceError::FfiStructType(atom) => {`
`@@ -483,6 +513,7 @@ impl MachineState {`
`483`	`513`	`MachineError {`
`484`	`514`	`stub,`
`485`	`515`	`location: None,`
	`516`	`+ file_name: None,`
`486`	`517`	`}`
`487`	`518`	`}`
`488`	`519`	`}`
`@@ -563,6 +594,7 @@ impl MachineState {`
`563`	`594`	`MachineError {`
`564`	`595`	`stub,`
`565`	`596`	`location: None,`
	`597`	`+ file_name: None,`
`566`	`598`	`}`
`567`	`599`	`}`
`568`	`600`
`@@ -650,7 +682,11 @@ impl MachineState {`
`650`	`682`
`651`	`683`	`let stub = functor!(atom!("syntax_error"), [functor(stub)]);`
`652`	`684`
`653`		`- MachineError { stub, location }`
	`685`	`+ MachineError {`
	`686`	`+ stub,`
	`687`	`+ location,`
	`688`	`+ file_name: None,`
	`689`	`+ }`
`654`	`690`	`}`
`655`	`691`
`656`	`692`	`pub(super) fn representation_error(&self, flag: RepFlag) -> MachineError {`
`@@ -662,6 +698,7 @@ impl MachineState {`
`662`	`698`	`MachineError {`
`663`	`699`	`stub,`
`664`	`700`	`location: None,`
	`701`	`+ file_name: None,`
`665`	`702`	`}`
`666`	`703`	`}`
`667`	`704`
`@@ -677,6 +714,7 @@ impl MachineState {`
`677`	`714`	`MachineError {`
`678`	`715`	`stub,`
`679`	`716`	`location: None,`
	`717`	`+ file_name: None,`
`680`	`718`	`}`
`681`	`719`	`}`
`682`	`720`
`@@ -686,6 +724,7 @@ impl MachineState {`
`686`	`724`	`MachineError {`
`687`	`725`	`stub,`
`688`	`726`	`location: None,`
	`727`	`+ file_name: None,`
`689`	`728`	`}`
`690`	`729`	`}`
`691`	`730`
`@@ -701,6 +740,7 @@ impl MachineState {`
`701`	`740`	`MachineError {`
`702`	`741`	`stub,`
`703`	`742`	`location: None,`
	`743`	`+ file_name: None,`
`704`	`744`	`}`
`705`	`745`	`}`
`706`	`746`	`FfiError::ValueOutOfRange(domain, culprit) => self.domain_error(domain, culprit),`
`@@ -726,6 +766,7 @@ impl MachineState {`
`726`	`766`	`FfiError::AllocationFailed => MachineError {`
`727`	`767`	`stub: functor!(atom!("resource_error"), [atom_as_cell((atom!("heap")))]),`
`728`	`768`	`location: None,`
	`769`	`+ file_name: None,`
`729`	`770`	`},`
`730`	`771`	`FfiError::LayoutError => self.representation_error(RepFlag::FfiLayout),`
`731`	`772`	`FfiError::UnsupportedTypedef => self.representation_error(RepFlag::FfiLayout),`
`@@ -747,16 +788,32 @@ impl MachineState {`
`747`	`788`
`748`	`789`	`pub(super) fn error_form(&mut self, err: MachineError, src: MachineStub) -> MachineStub {`
`749`	`790`	`if let Some((line_num, _col_num)) = err.location {`
`750`		`- functor!(`
`751`		`- atom!("error"),`
`752`		`- [`
`753`		`- functor((err.stub)),`
`754`		`- functor(`
`755`		`- (atom!(":")),`
`756`		`- [functor(src), number(line_num, (&mut self.arena))]`
`757`		`- )`
`758`		`- ]`
`759`		`- )`
	`791`	`+ // Include file name in error if available`
	`792`	`+ if let Some(file_name) = err.file_name {`
	`793`	`+ let file_cell = atom_as_cell!(file_name);`
	`794`	`+`
	`795`	`+ functor!(`
	`796`	`+ atom!("error"),`
	`797`	`+ [`
	`798`	`+ functor((err.stub)),`
	`799`	`+ functor(`
	`800`	`+ (atom!(":")),`
	`801`	`+ [cell(file_cell), number(line_num, (&mut self.arena))]`
	`802`	`+ )`
	`803`	`+ ]`
	`804`	`+ )`
	`805`	`+ } else {`
	`806`	`+ functor!(`
	`807`	`+ atom!("error"),`
	`808`	`+ [`
	`809`	`+ functor((err.stub)),`
	`810`	`+ functor(`
	`811`	`+ (atom!(":")),`
	`812`	`+ [functor(src), number(line_num, (&mut self.arena))]`
	`813`	`+ )`
	`814`	`+ ]`
	`815`	`+ )`
	`816`	`+ }`
`760`	`817`	`} else {`
`761`	`818`	`functor!(atom!("error"), [functor((err.stub)), functor(src)])`
`762`	`819`	`}`
Original file line number	Diff line number	Diff line change
`@@ -843,7 +843,9 @@ impl MachineState {`
`843`	`843`	`}`
`844`	`844`
`845`	`845`	`let stub = functor_stub(atom!("read_term"), 3);`
`846`		`- let err = self.syntax_error(err);`
	`846`	`+ let mut err = self.syntax_error(err);`
	`847`	`+ // Add file name to error if available`
	`848`	`+ err.set_file_name(stream.file_name());`
`847`	`849`
`848`	`850`	`return Err(self.error_form(err, stub));`
`849`	`851`	`}`